diff --git a/.gitattributes b/.gitattributes
index 7c0fa03..7950037 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -3,6 +3,8 @@
 .gitattributes   export-ignore
 .gitignore       export-ignore
 .scrutinizer.yml export-ignore
+.styleci.yml     export-ignore
+.php_cs.yml      export-ignore
 .travis.yml      export-ignore
 CONDUCT.md       export-ignore
 CONTRIBUTING.md  export-ignore
diff --git a/.github/workflows/Build-Test.yml b/.github/workflows/Build-Test.yml
new file mode 100644
index 0000000..3c8d40e
--- /dev/null
+++ b/.github/workflows/Build-Test.yml
@@ -0,0 +1,51 @@
+name: Tests
+
+on:
+  push:
+    branches:
+      - '*.x'
+  pull_request:
+
+jobs:
+  tests:
+    if: "! contains(toJSON(github.event.commits.*.msg), 'skip') && ! contains(toJSON(github.event.commits.*.msg), 'ci')" #skip ci...
+    runs-on: ${{ matrix.operating-system }}
+
+    strategy:
+      fail-fast: false
+      matrix:
+        operating-system: [ubuntu-22.04]
+        php-versions: ['7.4', '8.0', '8.1', '8.2', '8.3', '8.4']
+        include:
+          - operating-system: ubuntu-20.04
+            php-versions: '7.4'
+            COMPOSER_FLAGS: '--prefer-stable --prefer-lowest'
+            PHPUNIT_FLAGS: '--coverage-clover build/coverage.xml'
+
+    name: PHP ${{ matrix.php-versions }} - ${{ matrix.operating-system }}
+
+    env:
+      extensions: curl json libxml dom
+      key: cache-v1 # can be any string, change to clear the extension cache.
+
+    steps:
+      # Checks out a copy of your repository on the ubuntu machine
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Setup PHP Action
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: ${{ matrix.php-versions }}
+          extensions: ${{ env.extensions }}
+          coverage: xdebug
+          tools: 'composer:v2, pecl'
+
+      - name: Install Composer dependencies
+        run: composer update ${{ matrix.COMPOSER_FLAGS }} --no-interaction
+
+      - name: boot test server
+        run: vendor/bin/http_test_server > /dev/null 2>&1 &
+
+      - name: Run tests
+        run: composer test
diff --git a/.gitignore b/.gitignore
index e45d856..396c451 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
+.puli/
 build/
 vendor/
 composer.lock
diff --git a/.travis.yml b/.travis.yml
deleted file mode 100644
index f0e1cf3..0000000
--- a/.travis.yml
+++ /dev/null
@@ -1,38 +0,0 @@
-language: php
-
-sudo: false
-
-cache:
-  directories:
-    - $HOME/.composer/cache
-
-php:
-  - 5.5
-  - 5.6
-  - 7.0
-  - hhvm
-
-env:
-  global:
-    - TEST_COMMAND="composer test"
-
-matrix:
-  fast_finish: true
-  include:
-    - php: 5.5
-      env: COMPOSER_FLAGS="--prefer-stable --prefer-lowest" COVERAGE=true PHPUNIT_FLAGS="--coverage-clover build/coverage.xml"
-
-before_install:
-  - travis_retry composer self-update
-
-install:
-  - travis_retry composer update ${COMPOSER_FLAGS} --prefer-source --no-interaction
-
-before_script: vendor/bin/http_test_server > /dev/null 2>&1 &
-
-script:
-  - $TEST_COMMAND
-
-after_success:
-  - if [[ "$COVERAGE" = true ]]; then wget https://scrutinizer-ci.com/ocular.phar; fi
-  - if [[ "$COVERAGE" = true ]]; then php ocular.phar code-coverage:upload --format=php-clover build/coverage.xml; fi
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 935f871..caef53e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,209 @@
 # Change Log
 
-## [Unreleased]
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## 2.3.3 - 2024-10-31
+
+### Added
+
+- Added support for PHP 8.4
+
+## 2.3.2 - 2024-03-03
+
+### Fixed
+
+- Fixed running the tests with Guzzle PSR-7 and PSR-17 implementations.
+
+## 2.3.1 - 2023-11-03
+
+### Added
+
+- Allow installation with Symfony 7.
+
+## 2.3.0 - 2023-04-28
+
+### Added
+
+- Test with PHP 8.2
+
+### Fixed
+
+- This client needs a PSR-17 factories implementation. Instead of requiring an implementation,
+  previous versions only required the interfaces which could lead to a non-functional installation.
+  Fixed by requiring `psr/http-factory-implementation`.
+
+## 2.2.1 - 2021-12-10
+
+### Added
+
+- Symfony 6 support
+- Tested with PHP 8.1
+
+## 2.2.0 - 2020-12-14
+
+### Added
+
+- PHP 8.0 support
+
+## 2.1.0 - 2019-12-27
+
+### Added
+
+- Symfony 5 support
+
+## 2.0.0 - 2019-03-05
+
+### Removed
+
+- HHVM support removed.
+
+### Changed
+
+- Minimal PHP version changed to 7.1.
+- `Client::__construct` now expects PSR-17 factories instead of HTTPlug ones.
+
+### Added
+
+- #41: Support [PSR-17](https://www.php-fig.org/psr/psr-17/) and
+  [PSR-18](https://www.php-fig.org/psr/psr-18/).
+
+
+## 1.7.1 - 2018-03-26
+
+### Fixed
+
+- #36: Failure evaluating code: `is_resource($handle)` (string assertions are deprecated in PHP 7.2)
+
+
+## 1.7 - 2017-02-09
+
+### Changed
+
+- #30: Make sure we rewind streams
+
+## 1.6.2 - 2017-01-02
+
+### Fixed
+
+- #29: Request not using CURLOPT_POSTFIELDS have content-length set to
+
+### Changed
+
+- Use binary mode to create response body stream.
+
+
+## 1.6.1 - 2016-11-11
+
+### Fixed
+
+- #27: ErrorPlugin and sendAsyncRequest() incompatibility
+
+
+## 1.6 - 2016-09-12
+
+### Changed
+
+- `Client::sendRequest` now throws `Http\Client\Exception\NetworkException` on network errors.
+- `\UnexpectedValueException` replaced with `Http\Client\Exception\RequestException` in
+  `Client::sendRequest` and `Client::sendAsyncRequest`
+
+
+## 1.5.1 - 2016-08-29
+
+### Fixed
+
+- #26: Combining CurlClient with StopwatchPlugin causes Promise onRejected handler to never be
+  invoked.
+
+
+## 1.5 - 2016-08-03
+
+### Changed
+
+- Request body can be send with any method except GET, HEAD and TRACE.
+- #25: Make discovery a hard dependency.
+
+
+## 1.4.2 - 2016-06-14
+
+### Added
+
+- #23: "php-http/async-client-implementation" added to "provide" section.
+
+
+## 1.4.1 - 2016-05-30
+
+### Fixed
+
+- #22: Cannot create the client using `HttpClientDiscovery`.
+
+
+## 1.4 - 2016-03-30
+
+### Changed
+
+- #20: Minimize memory usage when reading large response body.
+
+
+## 1.3 - 2016-03-14
+
+### Fixed
+
+- #18: Invalid "Expect" header.
+
+### Removed
+
+- #13: Remove HeaderParser.
+
+
+## 1.2 - 2016-03-09
+
+### Added
+
+- #16: Make sure discovery can find the curl client
+
+### Fixed
+
+- #15: "Out of memory" sending large files.
+
+
+## 1.1.0 - 2016-01-29
+
+### Changed
+
+- Switch to php-http/message 1.0.
+
+
+## 1.0.0 - 2016-01-28
+
+First stable release.
+
+
+## 0.7.0 - 2016-01-26
+
+### Changed
+
+- Migrate from `php-http/discovery` and `php-http/utils` to `php-http/message`.
+
+## 0.6.0 - 2016-01-12
+
+### Changed
+
+- Root namespace changed from `Http\Curl` to `Http\Client\Curl`.
+- Main client class name renamed from `CurlHttpClient` to `Client`.
+- Minimum required [php-http/discovery](https://packagist.org/packages/php-http/discovery)
+  version changed to 0.5.
+
+
+## 0.5.0 - 2015-12-18
+
+### Changed
+
+- Compatibility with php-http/httplug 1.0 beta
+- Switch to php-http/discovery 0.4
 
 
 ## 0.4.0 - 2015-12-16
diff --git a/README.md b/README.md
index ff88ea2..71ab2ea 100644
--- a/README.md
+++ b/README.md
@@ -2,9 +2,7 @@
 
 [![Latest Version](https://img.shields.io/github/release/php-http/curl-client.svg?style=flat-square)](https://github.com/php-http/curl-client/releases)
 [![Software License](https://img.shields.io/badge/license-MIT-brightgreen.svg?style=flat-square)](LICENSE)
-[![Build Status](https://img.shields.io/travis/php-http/curl-client.svg?style=flat-square)](https://travis-ci.org/php-http/curl-client)
-[![Code Coverage](https://img.shields.io/scrutinizer/coverage/g/php-http/curl-client.svg?style=flat-square)](https://scrutinizer-ci.com/g/php-http/curl-client)
-[![Quality Score](https://img.shields.io/scrutinizer/g/php-http/curl-client.svg?style=flat-square)](https://scrutinizer-ci.com/g/php-http/curl-client)
+[![Tests](https://github.com/php-http/curl-client/actions/workflows/Build-Test.yml/badge.svg?branch=2.x)](https://github.com/php-http/curl-client/actions/workflows/Build-Test.yml)
 [![Total Downloads](https://img.shields.io/packagist/dt/php-http/curl-client.svg?style=flat-square)](https://packagist.org/packages/php-http/curl-client)
 
 The cURL client use the cURL PHP extension which must be activated in your `php.ini`.
@@ -18,71 +16,9 @@ Via Composer
 $ composer require php-http/curl-client
 ```
 
-## Usage
-
-### Using [php-http/discovery](https://packagist.org/packages/php-http/discovery):
-
-```php
-use Http\Curl\CurlHttpClient;
-use Http\Discovery\MessageFactory\GuzzleMessageFactory;
-use Http\Discovery\StreamFactory\GuzzleStreamFactory;
-
-$messageFactory = new GuzzleMessageFactory();
-$client = new CurlHttpClient($messageFactory, new GuzzleStreamFactory());
-
-$request = $messageFactory->createRequest('GET', 'http://example.com/');
-$response = $client->sendRequest($request);
-```
-
-### Using [mekras/httplug-diactoros-bridge](https://packagist.org/packages/mekras/httplug-diactoros-bridge):
-
-```php
-use Http\Curl\CurlHttpClient;
-use Mekras\HttplugDiactorosBridge\DiactorosMessageFactory;
-use Mekras\HttplugDiactorosBridge\DiactorosStreamFactory;
-
-$messageFactory = new DiactorosMessageFactory();
-$client = new CurlHttpClient($messageFactory, new DiactorosStreamFactory());
-
-$request = $messageFactory->createRequest('GET', 'http://example.com/');
-$response = $client->sendRequest($request);
-```
-
-### Configuring client
-
-You can use [cURL options](http://php.net/curl_setopt) to configure CurlHttpClient:
-
-```php
-use Http\Curl\CurlHttpClient;
-use Http\Discovery\MessageFactory\GuzzleMessageFactory;
-use Http\Discovery\StreamFactory\GuzzleStreamFactory;
-
-$options = [
-    CURLOPT_CONNECTTIMEOUT => 10, // The number of seconds to wait while trying to connect. 
-    CURLOPT_SSL_VERIFYPEER => false // Stop cURL from verifying the peer's certificate
-];
-$client = new CurlHttpClient(new GuzzleMessageFactory(), new GuzzleStreamFactory(), $options);
-```
-
-These options can not ne used:
-
-* CURLOPT_CUSTOMREQUEST
-* CURLOPT_FOLLOWLOCATION
-* CURLOPT_HEADER
-* CURLOPT_HTTP_VERSION
-* CURLOPT_HTTPHEADER
-* CURLOPT_NOBODY
-* CURLOPT_POSTFIELDS
-* CURLOPT_RETURNTRANSFER
-* CURLOPT_URL
-
-These options can be overwritten by CurlHttpClient:
-
-* CURLOPT_USERPWD
-
 ## Documentation
 
-Please see the [official documentation](http://php-http.readthedocs.org/en/latest/).
+Please see the [official documentation](http://docs.php-http.org/en/latest/clients/curl-client.html).
 
 ## Testing
 
diff --git a/composer.json b/composer.json
index a4ccf1d..cb1d971 100644
--- a/composer.json
+++ b/composer.json
@@ -1,45 +1,58 @@
 {
     "name": "php-http/curl-client",
-    "description": "cURL client for PHP-HTTP",
+    "description": "PSR-18 and HTTPlug Async client with cURL",
     "license": "MIT",
-    "keywords": ["http", "curl"],
-    "homepage": "http://php-http.org",
-    "authors": [
-        {
-            "name": "Михаил Красильников",
-            "email": "m.krasilnikov@yandex.ru"
-        }
+    "keywords": [
+        "curl",
+        "http",
+        "psr-18"
     ],
+    "homepage": "http://php-http.org",
+    "authors": [{
+        "name": "Михаил Красильников",
+        "email": "m.krasilnikov@yandex.ru"
+    }],
+    "prefer-stable": true,
+    "minimum-stability": "dev",
     "require": {
-        "php": ">=5.5",
+        "php": "^7.4 || ^8.0",
         "ext-curl": "*",
-        "php-http/httplug": "1.0.0-alpha3",
-        "php-http/message-factory": "^1.0"
+        "php-http/discovery": "^1.6",
+        "php-http/httplug": "^2.0",
+        "php-http/message": "^1.2",
+        "psr/http-client": "^1.0",
+        "psr/http-factory-implementation": "^1.0",
+        "symfony/options-resolver": "^3.4 || ^4.0 || ^5.0 || ^6.0 || ^7.0"
     },
     "require-dev": {
-        "guzzlehttp/psr7": "^1.0",
-        "php-http/adapter-integration-tests": "dev-master#48e5c0ee7b19772ab00060498f91886268b945c4",
-        "php-http/discovery": "dev-master#fd0cbe2ed125cc4f8fcc0378aff9874ce206e858",
-        "phpunit/phpunit": "^4.8@stable",
-        "zendframework/zend-diactoros": "^1.0"
+        "guzzlehttp/psr7": "^2.0",
+        "php-http/client-integration-tests": "^3.0",
+        "phpunit/phpunit": "^7.5 || ^9.4",
+        "laminas/laminas-diactoros": "^2.0 || ^3.0",
+        "php-http/message-factory": "^1.1"
     },
     "autoload": {
         "psr-4": {
-            "Http\\Curl\\": "src/"
+            "Http\\Client\\Curl\\": "src/"
         }
     },
     "autoload-dev": {
         "psr-4": {
-            "Http\\Curl\\Tests\\": "tests/"
+            "Http\\Client\\Curl\\Tests\\": "tests/"
         }
     },
     "provide": {
-        "php-http/client-implementation": "1.0"
+        "php-http/client-implementation": "1.0",
+        "php-http/async-client-implementation": "1.0",
+        "psr/http-client-implementation": "1.0"
     },
     "scripts": {
         "test": "vendor/bin/phpunit",
         "test-ci": "vendor/bin/phpunit --coverage-clover build/coverage.xml"
     },
-    "prefer-stable": true,
-    "minimum-stability": "dev"
+    "config": {
+        "allow-plugins": {
+            "php-http/discovery": false
+        }
+    }
 }
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index c2f6ec4..1df4f8a 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -1,16 +1,35 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<phpunit colors="true" bootstrap="vendor/autoload.php">
+
+<!-- https://phpunit.de/manual/current/en/appendixes.configuration.html -->
+<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:noNamespaceSchemaLocation="http://schema.phpunit.de/7.0/phpunit.xsd"
+         bootstrap="tests/bootstrap.php"
+         colors="true"
+>
+    <php>
+        <server name="TEST_SERVER" value="http://127.0.0.1:10000/server.php"/>
+    </php>
+
     <testsuites>
-        <testsuite name="Curl Client Test Suite">
-            <directory>tests/</directory>
+
+        <testsuite name="All">
+            <directory>tests</directory>
+        </testsuite>
+
+        <testsuite name="Unit">
+            <directory>tests/Unit</directory>
         </testsuite>
+
+        <testsuite name="Functional">
+            <directory>tests/Functional</directory>
+        </testsuite>
+
     </testsuites>
-    <php>
-        <server name="TEST_SERVER" value="http://127.0.0.1:10000/server.php" />
-    </php>
+
     <filter>
         <whitelist>
-            <directory suffix=".php">src/</directory>
+            <directory>src</directory>
         </whitelist>
     </filter>
+
 </phpunit>
diff --git a/puli.json b/puli.json
new file mode 100644
index 0000000..b35768d
--- /dev/null
+++ b/puli.json
@@ -0,0 +1,242 @@
+{
+    "version": "1.0",
+    "name": "php-http/curl-client",
+    "bindings": {
+        "98239b8b-103b-4f47-94c7-4cba49a05a1f": {
+            "_class": "Puli\\Discovery\\Binding\\ClassBinding",
+            "class": "Http\\Client\\Curl\\Client",
+            "type": "Http\\Client\\HttpAsyncClient"
+        },
+        "a6a79968-2aa5-427c-bbe1-a581d9a48321": {
+            "_class": "Puli\\Discovery\\Binding\\ClassBinding",
+            "class": "Http\\Client\\Curl\\Client",
+            "type": "Http\\Client\\HttpClient"
+        }
+    },
+    "config": {
+        "bootstrap-file": "vendor/autoload.php"
+    },
+    "packages": {
+        "clue/stream-filter": {
+            "install-path": "vendor/clue/stream-filter",
+            "installer": "composer",
+            "env": "dev"
+        },
+        "doctrine/instantiator": {
+            "install-path": "vendor/doctrine/instantiator",
+            "installer": "composer",
+            "env": "dev"
+        },
+        "guzzlehttp/psr7": {
+            "install-path": "vendor/guzzlehttp/psr7",
+            "installer": "composer",
+            "env": "dev"
+        },
+        "justinrainbow/json-schema": {
+            "install-path": "vendor/justinrainbow/json-schema",
+            "installer": "composer",
+            "env": "dev"
+        },
+        "paragonie/random_compat": {
+            "install-path": "vendor/paragonie/random_compat",
+            "installer": "composer",
+            "env": "dev"
+        },
+        "php-http/adapter-integration-tests": {
+            "install-path": "vendor/php-http/adapter-integration-tests",
+            "installer": "composer",
+            "env": "dev"
+        },
+        "php-http/discovery": {
+            "install-path": "vendor/php-http/discovery",
+            "installer": "composer",
+            "env": "dev"
+        },
+        "php-http/httplug": {
+            "install-path": "vendor/php-http/httplug",
+            "installer": "composer"
+        },
+        "php-http/message": {
+            "install-path": "vendor/php-http/message",
+            "installer": "composer",
+            "env": "dev"
+        },
+        "php-http/message-factory": {
+            "install-path": "vendor/php-http/message-factory",
+            "installer": "composer"
+        },
+        "php-http/promise": {
+            "install-path": "vendor/php-http/promise",
+            "installer": "composer"
+        },
+        "phpdocumentor/reflection-docblock": {
+            "install-path": "vendor/phpdocumentor/reflection-docblock",
+            "installer": "composer",
+            "env": "dev"
+        },
+        "phpspec/prophecy": {
+            "install-path": "vendor/phpspec/prophecy",
+            "installer": "composer",
+            "env": "dev"
+        },
+        "phpunit/php-code-coverage": {
+            "install-path": "vendor/phpunit/php-code-coverage",
+            "installer": "composer",
+            "env": "dev"
+        },
+        "phpunit/php-file-iterator": {
+            "install-path": "vendor/phpunit/php-file-iterator",
+            "installer": "composer",
+            "env": "dev"
+        },
+        "phpunit/php-text-template": {
+            "install-path": "vendor/phpunit/php-text-template",
+            "installer": "composer",
+            "env": "dev"
+        },
+        "phpunit/php-timer": {
+            "install-path": "vendor/phpunit/php-timer",
+            "installer": "composer",
+            "env": "dev"
+        },
+        "phpunit/php-token-stream": {
+            "install-path": "vendor/phpunit/php-token-stream",
+            "installer": "composer",
+            "env": "dev"
+        },
+        "phpunit/phpunit": {
+            "install-path": "vendor/phpunit/phpunit",
+            "installer": "composer",
+            "env": "dev"
+        },
+        "phpunit/phpunit-mock-objects": {
+            "install-path": "vendor/phpunit/phpunit-mock-objects",
+            "installer": "composer",
+            "env": "dev"
+        },
+        "psr/http-message": {
+            "install-path": "vendor/psr/http-message",
+            "installer": "composer"
+        },
+        "psr/log": {
+            "install-path": "vendor/psr/log",
+            "installer": "composer",
+            "env": "dev"
+        },
+        "puli/composer-plugin": {
+            "install-path": "vendor/puli/composer-plugin",
+            "installer": "composer",
+            "env": "dev"
+        },
+        "puli/discovery": {
+            "install-path": "vendor/puli/discovery",
+            "installer": "composer",
+            "env": "dev"
+        },
+        "puli/repository": {
+            "install-path": "vendor/puli/repository",
+            "installer": "composer",
+            "env": "dev"
+        },
+        "puli/url-generator": {
+            "install-path": "vendor/puli/url-generator",
+            "installer": "composer",
+            "env": "dev"
+        },
+        "ramsey/uuid": {
+            "install-path": "vendor/ramsey/uuid",
+            "installer": "composer",
+            "env": "dev"
+        },
+        "sebastian/comparator": {
+            "install-path": "vendor/sebastian/comparator",
+            "installer": "composer",
+            "env": "dev"
+        },
+        "sebastian/diff": {
+            "install-path": "vendor/sebastian/diff",
+            "installer": "composer",
+            "env": "dev"
+        },
+        "sebastian/environment": {
+            "install-path": "vendor/sebastian/environment",
+            "installer": "composer",
+            "env": "dev"
+        },
+        "sebastian/exporter": {
+            "install-path": "vendor/sebastian/exporter",
+            "installer": "composer",
+            "env": "dev"
+        },
+        "sebastian/global-state": {
+            "install-path": "vendor/sebastian/global-state",
+            "installer": "composer",
+            "env": "dev"
+        },
+        "sebastian/recursion-context": {
+            "install-path": "vendor/sebastian/recursion-context",
+            "installer": "composer",
+            "env": "dev"
+        },
+        "sebastian/version": {
+            "install-path": "vendor/sebastian/version",
+            "installer": "composer",
+            "env": "dev"
+        },
+        "seld/jsonlint": {
+            "install-path": "vendor/seld/jsonlint",
+            "installer": "composer",
+            "env": "dev"
+        },
+        "symfony/filesystem": {
+            "install-path": "vendor/symfony/filesystem",
+            "installer": "composer",
+            "env": "dev"
+        },
+        "symfony/process": {
+            "install-path": "vendor/symfony/process",
+            "installer": "composer",
+            "env": "dev"
+        },
+        "symfony/yaml": {
+            "install-path": "vendor/symfony/yaml",
+            "installer": "composer",
+            "env": "dev"
+        },
+        "th3n3rd/cartesian-product": {
+            "install-path": "vendor/th3n3rd/cartesian-product",
+            "installer": "composer",
+            "env": "dev"
+        },
+        "webmozart/assert": {
+            "install-path": "vendor/webmozart/assert",
+            "installer": "composer",
+            "env": "dev"
+        },
+        "webmozart/expression": {
+            "install-path": "vendor/webmozart/expression",
+            "installer": "composer",
+            "env": "dev"
+        },
+        "webmozart/glob": {
+            "install-path": "vendor/webmozart/glob",
+            "installer": "composer",
+            "env": "dev"
+        },
+        "webmozart/json": {
+            "install-path": "vendor/webmozart/json",
+            "installer": "composer",
+            "env": "dev"
+        },
+        "webmozart/path-util": {
+            "install-path": "vendor/webmozart/path-util",
+            "installer": "composer",
+            "env": "dev"
+        },
+        "zendframework/zend-diactoros": {
+            "install-path": "vendor/zendframework/zend-diactoros",
+            "installer": "composer",
+            "env": "dev"
+        }
+    }
+}
diff --git a/src/Client.php b/src/Client.php
new file mode 100644
index 0000000..d3fd6bd
--- /dev/null
+++ b/src/Client.php
@@ -0,0 +1,398 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Http\Client\Curl;
+
+use Http\Client\Exception;
+use Http\Client\HttpAsyncClient;
+use Http\Client\HttpClient;
+use Http\Discovery\Exception\NotFoundException;
+use Http\Discovery\Psr17FactoryDiscovery;
+use Http\Promise\Promise;
+use Psr\Http\Message\RequestInterface;
+use Psr\Http\Message\ResponseFactoryInterface;
+use Psr\Http\Message\ResponseInterface;
+use Psr\Http\Message\StreamFactoryInterface;
+use Symfony\Component\OptionsResolver\OptionsResolver;
+
+/**
+ * PSR-18 and HTTPlug Async client based on lib-curl.
+ *
+ * @license http://opensource.org/licenses/MIT MIT
+ * @author  Михаил Красильников <m.krasilnikov@yandex.ru>
+ * @author  Blake Williams <github@shabbyrobe.org>
+ *
+ * @api
+ *
+ * @since   1.0
+ */
+class Client implements HttpClient, HttpAsyncClient
+{
+    /**
+     * cURL options.
+     *
+     * @var array
+     */
+    private $curlOptions;
+
+    /**
+     * PSR-17 response factory.
+     *
+     * @var ResponseFactoryInterface
+     */
+    private $responseFactory;
+
+    /**
+     * PSR-17 stream factory.
+     *
+     * @var StreamFactoryInterface
+     */
+    private $streamFactory;
+
+    /**
+     * cURL synchronous requests handle.
+     *
+     * @var resource|\CurlHandle|null
+     */
+    private $handle;
+
+    /**
+     * Simultaneous requests runner.
+     *
+     * @var MultiRunner|null
+     */
+    private $multiRunner;
+
+    /**
+     * Create HTTP client.
+     *
+     * @param ResponseFactoryInterface|null $responseFactory PSR-17 HTTP response factory.
+     * @param StreamFactoryInterface|null   $streamFactory   PSR-17 HTTP stream factory.
+     * @param array                         $options         cURL options
+     *                                                       {@link http://php.net/curl_setopt}.
+     *
+     * @throws NotFoundException If factory discovery failed.
+     *
+     * @since 2.0 Accepts PSR-17 factories instead of HTTPlug ones.
+     */
+    public function __construct(
+        ?ResponseFactoryInterface $responseFactory = null,
+        ?StreamFactoryInterface $streamFactory = null,
+        array $options = []
+    ) {
+        $this->responseFactory = $responseFactory ?: Psr17FactoryDiscovery::findResponseFactory();
+        $this->streamFactory = $streamFactory ?: Psr17FactoryDiscovery::findStreamFactory();
+        $resolver = new OptionsResolver();
+        $resolver->setDefaults(
+            [
+                CURLOPT_HEADER => false,
+                CURLOPT_RETURNTRANSFER => false,
+                CURLOPT_FOLLOWLOCATION => false
+            ]
+        );
+
+        // Our parsing will fail if this is set to true.
+        $resolver->setAllowedValues(
+            (string)CURLOPT_HEADER,
+            [false]
+        );
+
+        // Our parsing will fail if this is set to true.
+        $resolver->setAllowedValues(
+            (string)CURLOPT_RETURNTRANSFER,
+            [false]
+        );
+
+        // We do not know what everything curl supports and might support in the future.
+        // Make sure that we accept everything that is in the options.
+        $resolver->setDefined(array_keys($options));
+
+        $this->curlOptions = $resolver->resolve($options);
+    }
+
+    /**
+     * Release resources if still active.
+     */
+    public function __destruct()
+    {
+        if (is_resource($this->handle)) {
+            curl_close($this->handle);
+        }
+    }
+
+    /**
+     * Sends a PSR-7 request and returns a PSR-7 response.
+     *
+     * @param RequestInterface $request
+     *
+     * @return ResponseInterface
+     *
+     * @throws \InvalidArgumentException  For invalid header names or values.
+     * @throws \RuntimeException          If creating the body stream fails.
+     * @throws Exception\NetworkException In case of network problems.
+     * @throws Exception\RequestException On invalid request.
+     *
+     * @since 1.6 \UnexpectedValueException replaced with RequestException
+     * @since 1.6 Throw NetworkException on network errors
+     * @since 1.0
+     */
+    public function sendRequest(RequestInterface $request): ResponseInterface
+    {
+        $responseBuilder = $this->createResponseBuilder();
+        $requestOptions = $this->prepareRequestOptions($request, $responseBuilder);
+
+        if (is_resource($this->handle)) {
+            curl_reset($this->handle);
+        } else {
+            $this->handle = curl_init();
+        }
+
+        curl_setopt_array($this->handle, $requestOptions);
+        curl_exec($this->handle);
+
+        $errno = curl_errno($this->handle);
+        switch ($errno) {
+            case CURLE_OK:
+                // All OK, no actions needed.
+                break;
+            case CURLE_COULDNT_RESOLVE_PROXY:
+            case CURLE_COULDNT_RESOLVE_HOST:
+            case CURLE_COULDNT_CONNECT:
+            case CURLE_OPERATION_TIMEOUTED:
+            case CURLE_SSL_CONNECT_ERROR:
+                throw new Exception\NetworkException(curl_error($this->handle), $request);
+            default:
+                throw new Exception\RequestException(curl_error($this->handle), $request);
+        }
+
+        $response = $responseBuilder->getResponse();
+        $response->getBody()->seek(0);
+
+        return $response;
+    }
+
+    /**
+     * Create builder to use for building response object.
+     *
+     * @return ResponseBuilder
+     */
+    private function createResponseBuilder(): ResponseBuilder
+    {
+        $body = $this->streamFactory->createStreamFromFile('php://temp', 'w+b');
+
+        $response = $this->responseFactory
+            ->createResponse(200)
+            ->withBody($body);
+
+        return new ResponseBuilder($response);
+    }
+
+    /**
+     * Update cURL options for given request and hook in the response builder.
+     *
+     * @param RequestInterface $request         Request on which to create options.
+     * @param ResponseBuilder  $responseBuilder Builder to use for building response.
+     *
+     * @return array cURL options based on request.
+     *
+     * @throws \InvalidArgumentException  For invalid header names or values.
+     * @throws \RuntimeException          If can not read body.
+     * @throws Exception\RequestException On invalid request.
+     */
+    private function prepareRequestOptions(
+        RequestInterface $request,
+        ResponseBuilder $responseBuilder
+    ): array {
+        $curlOptions = $this->curlOptions;
+
+        try {
+            $curlOptions[CURLOPT_HTTP_VERSION]
+                = $this->getProtocolVersion($request->getProtocolVersion());
+        } catch (\UnexpectedValueException $e) {
+            throw new Exception\RequestException($e->getMessage(), $request);
+        }
+        $curlOptions[CURLOPT_URL] = (string)$request->getUri();
+
+        $curlOptions = $this->addRequestBodyOptions($request, $curlOptions);
+
+        $curlOptions[CURLOPT_HTTPHEADER] = $this->createHeaders($request, $curlOptions);
+
+        if ($request->getUri()->getUserInfo()) {
+            $curlOptions[CURLOPT_USERPWD] = $request->getUri()->getUserInfo();
+        }
+
+        $curlOptions[CURLOPT_HEADERFUNCTION] = function ($ch, $data) use ($responseBuilder) {
+            $str = trim($data);
+            if ('' !== $str) {
+                if (stripos($str, 'http/') === 0) {
+                    $responseBuilder->setStatus($str)->getResponse();
+                } else {
+                    $responseBuilder->addHeader($str);
+                }
+            }
+
+            return strlen($data);
+        };
+
+        $curlOptions[CURLOPT_WRITEFUNCTION] = function ($ch, $data) use ($responseBuilder) {
+            return $responseBuilder->getResponse()->getBody()->write($data);
+        };
+
+        return $curlOptions;
+    }
+
+    /**
+     * Return cURL constant for specified HTTP version.
+     *
+     * @param string $requestVersion HTTP version ("1.0", "1.1" or "2.0").
+     *
+     * @return int Respective CURL_HTTP_VERSION_x_x constant.
+     *
+     * @throws \UnexpectedValueException If unsupported version requested.
+     */
+    private function getProtocolVersion(string $requestVersion): int
+    {
+        switch ($requestVersion) {
+            case '1.0':
+                return CURL_HTTP_VERSION_1_0;
+            case '1.1':
+                return CURL_HTTP_VERSION_1_1;
+            case '2.0':
+                if (defined('CURL_HTTP_VERSION_2_0')) {
+                    return CURL_HTTP_VERSION_2_0;
+                }
+                throw new \UnexpectedValueException('libcurl 7.33 needed for HTTP 2.0 support');
+        }
+
+        return CURL_HTTP_VERSION_NONE;
+    }
+
+    /**
+     * Add request body related cURL options.
+     *
+     * @param RequestInterface $request     Request on which to create options.
+     * @param array            $curlOptions Options created by prepareRequestOptions().
+     *
+     * @return array cURL options based on request.
+     */
+    private function addRequestBodyOptions(RequestInterface $request, array $curlOptions): array
+    {
+        /*
+         * Some HTTP methods cannot have payload:
+         *
+         * - GET — cURL will automatically change method to PUT or POST if we set CURLOPT_UPLOAD or
+         *   CURLOPT_POSTFIELDS.
+         * - HEAD — cURL treats HEAD as GET request with a same restrictions.
+         * - TRACE — According to RFC7231: a client MUST NOT send a message body in a TRACE request.
+         */
+        if (!in_array($request->getMethod(), ['GET', 'HEAD', 'TRACE'], true)) {
+            $body = $request->getBody();
+            $bodySize = $body->getSize();
+            if ($bodySize !== 0) {
+                if ($body->isSeekable()) {
+                    $body->rewind();
+                }
+
+                // Message has non empty body.
+                if (null === $bodySize || $bodySize > 1024 * 1024) {
+                    // Avoid full loading large or unknown size body into memory
+                    $curlOptions[CURLOPT_UPLOAD] = true;
+                    if (null !== $bodySize) {
+                        $curlOptions[CURLOPT_INFILESIZE] = $bodySize;
+                    }
+                    $curlOptions[CURLOPT_READFUNCTION] = function ($ch, $fd, $length) use ($body) {
+                        return $body->read($length);
+                    };
+                } else {
+                    // Small body can be loaded into memory
+                    $curlOptions[CURLOPT_POSTFIELDS] = (string)$body;
+                }
+            }
+        }
+
+        if ($request->getMethod() === 'HEAD') {
+            // This will set HTTP method to "HEAD".
+            $curlOptions[CURLOPT_NOBODY] = true;
+        } elseif ($request->getMethod() !== 'GET') {
+            // GET is a default method. Other methods should be specified explicitly.
+            $curlOptions[CURLOPT_CUSTOMREQUEST] = $request->getMethod();
+        }
+
+        return $curlOptions;
+    }
+
+    /**
+     * Create headers array for CURLOPT_HTTPHEADER.
+     *
+     * @param RequestInterface $request     Request on which to create headers.
+     * @param array            $curlOptions Options created by prepareRequestOptions().
+     *
+     * @return string[]
+     */
+    private function createHeaders(RequestInterface $request, array $curlOptions): array
+    {
+        $curlHeaders = [];
+        $headers = $request->getHeaders();
+        foreach ($headers as $name => $values) {
+            $header = strtolower($name);
+            if ('expect' === $header) {
+                // curl-client does not support "Expect-Continue", so dropping "expect" headers
+                continue;
+            }
+            if ('content-length' === $header) {
+                if (array_key_exists(CURLOPT_POSTFIELDS, $curlOptions)) {
+                    // Small body content length can be calculated here.
+                    $values = [strlen($curlOptions[CURLOPT_POSTFIELDS])];
+                } elseif (!array_key_exists(CURLOPT_READFUNCTION, $curlOptions)) {
+                    // Else if there is no body, forcing "Content-length" to 0
+                    $values = [0];
+                }
+            }
+            foreach ($values as $value) {
+                $curlHeaders[] = $name . ': ' . $value;
+            }
+        }
+        /*
+         * curl-client does not support "Expect-Continue", but cURL adds "Expect" header by default.
+         * We can not suppress it, but we can set it to empty.
+         */
+        $curlHeaders[] = 'Expect:';
+
+        return $curlHeaders;
+    }
+
+    /**
+     * Sends a PSR-7 request in an asynchronous way.
+     *
+     * Exceptions related to processing the request are available from the returned Promise.
+     *
+     * @param RequestInterface $request
+     *
+     * @return Promise Resolves a PSR-7 Response or fails with an Http\Client\Exception.
+     *
+     * @throws \InvalidArgumentException  For invalid header names or values.
+     * @throws \RuntimeException          If creating the body stream fails.
+     * @throws Exception\RequestException On invalid request.
+     *
+     * @since 1.6 \UnexpectedValueException replaced with RequestException
+     * @since 1.0
+     */
+    public function sendAsyncRequest(RequestInterface $request)
+    {
+        if (!$this->multiRunner instanceof MultiRunner) {
+            $this->multiRunner = new MultiRunner();
+        }
+
+        $handle = curl_init();
+        $responseBuilder = $this->createResponseBuilder();
+        $requestOptions = $this->prepareRequestOptions($request, $responseBuilder);
+        curl_setopt_array($handle, $requestOptions);
+
+        $core = new PromiseCore($request, $handle, $responseBuilder);
+        $promise = new CurlPromise($core, $this->multiRunner);
+        $this->multiRunner->add($core);
+
+        return $promise;
+    }
+}
diff --git a/src/CurlHttpClient.php b/src/CurlHttpClient.php
deleted file mode 100644
index 533cd50..0000000
--- a/src/CurlHttpClient.php
+++ /dev/null
@@ -1,254 +0,0 @@
-<?php
-namespace Http\Curl;
-
-use Http\Client\Exception;
-use Http\Client\Exception\RequestException;
-use Http\Client\HttpAsyncClient;
-use Http\Client\HttpClient;
-use Http\Message\MessageFactory;
-use Http\Message\StreamFactory;
-use Http\Promise\Promise;
-use Psr\Http\Message\RequestInterface;
-use Psr\Http\Message\ResponseInterface;
-
-/**
- * PSR-7 compatible cURL based HTTP client
- *
- * @license http://opensource.org/licenses/MIT MIT
- *
- * @author  Михаил Красильников <m.krasilnikov@yandex.ru>
- * @author  Blake Williams <github@shabbyrobe.org>
- *
- * @api
- * @since   1.0
- */
-class CurlHttpClient implements HttpClient, HttpAsyncClient
-{
-    /**
-     * cURL options
-     *
-     * @var array
-     */
-    private $options;
-
-    /**
-     * cURL response parser
-     *
-     * @var ResponseParser
-     */
-    private $responseParser;
-
-    /**
-     * cURL synchronous requests handle
-     *
-     * @var resource|null
-     */
-    private $handle = null;
-
-    /**
-     * Simultaneous requests runner
-     *
-     * @var MultiRunner|null
-     */
-    private $multiRunner = null;
-
-    /**
-     * Create new client
-     *
-     * Available options:
-     *
-     * - connection_timeout : int —  connection timeout in seconds;
-     * - curl_options: array — custom cURL options;
-     * - ssl_verify_peer : bool — verify peer when using SSL;
-     * - timeout : int —  overall timeout in seconds.
-     *
-     * @param MessageFactory $messageFactory HTTP Message factory
-     * @param StreamFactory  $streamFactory  HTTP Stream factory
-     * @param array          $options        cURL options (see http://php.net/curl_setopt)
-     *
-     * @since 1.0
-     */
-    public function __construct(
-        MessageFactory $messageFactory,
-        StreamFactory $streamFactory,
-        array $options = []
-    ) {
-        $this->responseParser = new ResponseParser($messageFactory, $streamFactory);
-        $this->options = $options;
-    }
-
-    /**
-     * Release resources if still active
-     */
-    public function __destruct()
-    {
-        if (is_resource($this->handle)) {
-            curl_close($this->handle);
-        }
-    }
-
-    /**
-     * Sends a PSR-7 request.
-     *
-     * @param RequestInterface $request
-     *
-     * @return ResponseInterface
-     *
-     * @throws \UnexpectedValueException if unsupported HTTP version requested
-     * @throws RequestException
-     *
-     * @since 1.0
-     */
-    public function sendRequest(RequestInterface $request)
-    {
-        $options = $this->createCurlOptions($request);
-
-        if (is_resource($this->handle)) {
-            curl_reset($this->handle);
-        } else {
-            $this->handle = curl_init();
-        }
-
-        curl_setopt_array($this->handle, $options);
-        $raw = curl_exec($this->handle);
-
-        if (curl_errno($this->handle) > 0) {
-            throw new RequestException(curl_error($this->handle), $request);
-        }
-
-        $info = curl_getinfo($this->handle);
-
-        try {
-            $response = $this->responseParser->parse($raw, $info);
-        } catch (\Exception $e) {
-            throw new RequestException($e->getMessage(), $request, $e);
-        }
-        return $response;
-    }
-
-    /**
-     * Sends a PSR-7 request in an asynchronous way.
-     *
-     * @param RequestInterface $request
-     *
-     * @return Promise
-     *
-     * @throws Exception
-     * @throws \UnexpectedValueException if unsupported HTTP version requested
-     *
-     * @since 1.0
-     */
-    public function sendAsyncRequest(RequestInterface $request)
-    {
-        if (!$this->multiRunner instanceof MultiRunner) {
-            $this->multiRunner = new MultiRunner($this->responseParser);
-        }
-
-        $handle = curl_init();
-        $options = $this->createCurlOptions($request);
-        curl_setopt_array($handle, $options);
-
-        $core = new PromiseCore($request, $handle);
-        $promise = new CurlPromise($core, $this->multiRunner);
-        $this->multiRunner->add($core);
-
-        return $promise;
-    }
-
-    /**
-     * Generates cURL options
-     *
-     * @param RequestInterface $request
-     *
-     * @throws \UnexpectedValueException if unsupported HTTP version requested
-     *
-     * @return array
-     */
-    private function createCurlOptions(RequestInterface $request)
-    {
-        $options = $this->options;
-
-        $options[CURLOPT_HEADER] = true;
-        $options[CURLOPT_RETURNTRANSFER] = true;
-        $options[CURLOPT_FOLLOWLOCATION] = false;
-
-        $options[CURLOPT_HTTP_VERSION] = $this->getProtocolVersion($request->getProtocolVersion());
-        $options[CURLOPT_URL] = (string) $request->getUri();
-
-        if (in_array($request->getMethod(), ['OPTIONS', 'POST', 'PUT'], true)) {
-            // cURL allows request body only for these methods.
-            $body = (string) $request->getBody();
-            if ('' !== $body) {
-                $options[CURLOPT_POSTFIELDS] = $body;
-            }
-        }
-
-        if ($request->getMethod() === 'HEAD') {
-            $options[CURLOPT_NOBODY] = true;
-        } elseif ($request->getMethod() !== 'GET') {
-            // GET is a default method. Other methods should be specified explicitly.
-            $options[CURLOPT_CUSTOMREQUEST] = $request->getMethod();
-        }
-
-        $options[CURLOPT_HTTPHEADER] = $this->createHeaders($request, $options);
-
-        if ($request->getUri()->getUserInfo()) {
-            $options[CURLOPT_USERPWD] = $request->getUri()->getUserInfo();
-        }
-
-        return $options;
-    }
-
-    /**
-     * Return cURL constant for specified HTTP version
-     *
-     * @param string $requestVersion
-     *
-     * @throws \UnexpectedValueException if unsupported version requested
-     *
-     * @return int
-     */
-    private function getProtocolVersion($requestVersion)
-    {
-        switch ($requestVersion) {
-            case '1.0':
-                return CURL_HTTP_VERSION_1_0;
-            case '1.1':
-                return CURL_HTTP_VERSION_1_1;
-            case '2.0':
-                if (defined('CURL_HTTP_VERSION_2_0')) {
-                    return CURL_HTTP_VERSION_2_0;
-                }
-                throw new \UnexpectedValueException('libcurl 7.33 needed for HTTP 2.0 support');
-        }
-        return CURL_HTTP_VERSION_NONE;
-    }
-
-    /**
-     * Create headers array for CURLOPT_HTTPHEADER
-     *
-     * @param RequestInterface $request
-     * @param array            $options cURL options
-     *
-     * @return string[]
-     */
-    private function createHeaders(RequestInterface $request, array $options)
-    {
-        $curlHeaders = [];
-        $headers = array_keys($request->getHeaders());
-        foreach ($headers as $name) {
-            if (strtolower($name) === 'content-length') {
-                $values = [0];
-                if (array_key_exists(CURLOPT_POSTFIELDS, $options)) {
-                    $values = [strlen($options[CURLOPT_POSTFIELDS])];
-                }
-            } else {
-                $values = $request->getHeader($name);
-            }
-            foreach ($values as $value) {
-                $curlHeaders[] = $name . ': ' . $value;
-            }
-        }
-        return $curlHeaders;
-    }
-}
diff --git a/src/CurlPromise.php b/src/CurlPromise.php
index 9d21d53..d69494c 100644
--- a/src/CurlPromise.php
+++ b/src/CurlPromise.php
@@ -1,7 +1,9 @@
 <?php
-namespace Http\Curl;
 
-use Http\Client\Exception;
+declare(strict_types=1);
+
+namespace Http\Client\Curl;
+
 use Http\Promise\Promise;
 
 /**
@@ -13,20 +15,19 @@
  * Reason is replaced by an object where its class implement a Http\Client\Exception.
  *
  * @license http://opensource.org/licenses/MIT MIT
- *
  * @author  Михаил Красильников <m.krasilnikov@yandex.ru>
  */
 class CurlPromise implements Promise
 {
     /**
-     * Shared promise core
+     * Shared promise core.
      *
      * @var PromiseCore
      */
     private $core;
 
     /**
-     * Requests runner
+     * Requests runner.
      *
      * @var MultiRunner
      */
@@ -50,15 +51,15 @@ public function __construct(PromiseCore $core, MultiRunner $runner)
      * If you do not care about one of the cases, you can set the corresponding callable to null
      * The callback will be called when the response or exception arrived and never more than once.
      *
-     * @param callable $onFulfilled Called when a response will be available.
-     * @param callable $onRejected  Called when an error happens.
+     * @param callable|null $onFulfilled Called when a response will be available
+     * @param callable|null $onRejected  Called when an error happens.
      *
-     * You must always return the Response in the interface or throw an Exception.
+     * You must always return the Response in the interface or throw an Exception
      *
      * @return Promise Always returns a new promise which is resolved with value of the executed
-     *                 callback (onFulfilled / onRejected).
+     *                 callback (onFulfilled / onRejected)
      */
-    public function then(callable $onFulfilled = null, callable $onRejected = null)
+    public function then(?callable $onFulfilled = null, ?callable $onRejected = null)
     {
         if ($onFulfilled) {
             $this->core->addOnFulfilled($onFulfilled);
@@ -91,19 +92,20 @@ public function getState()
      *
      * @return \Psr\Http\Message\ResponseInterface|null Resolved value, null if $unwrap is set to false
      *
-     * @throws \Http\Client\Exception The rejection reason.
+     * @throws \Http\Client\Exception The rejection reason
      */
     public function wait($unwrap = true)
     {
         $this->runner->wait($this->core);
 
         if ($unwrap) {
-            if ($this->core->getState() == self::REJECTED) {
+            if ($this->core->getState() === self::REJECTED) {
                 throw $this->core->getException();
             }
 
             return $this->core->getResponse();
         }
+
         return null;
     }
 }
diff --git a/src/MultiRunner.php b/src/MultiRunner.php
index 815ab32..13f43a9 100644
--- a/src/MultiRunner.php
+++ b/src/MultiRunner.php
@@ -1,50 +1,35 @@
 <?php
-namespace Http\Curl;
+
+declare(strict_types=1);
+
+namespace Http\Client\Curl;
 
 use Http\Client\Exception\RequestException;
 
 /**
- * Simultaneous requests runner
+ * Simultaneous requests runner.
  *
  * @license http://opensource.org/licenses/MIT MIT
- *
  * @author  Михаил Красильников <m.krasilnikov@yandex.ru>
  */
 class MultiRunner
 {
     /**
-     * cURL multi handle
+     * cURL multi handle.
      *
      * @var resource|null
      */
-    private $multiHandle = null;
-
-    /**
-     * cURL response parser
-     *
-     * @var ResponseParser
-     */
-    private $responseParser;
+    private $multiHandle;
 
     /**
-     * Awaiting cores
+     * Awaiting cores.
      *
      * @var PromiseCore[]
      */
     private $cores = [];
 
     /**
-     * Construct new runner.
-     *
-     * @param ResponseParser $responseParser
-     */
-    public function __construct(ResponseParser $responseParser)
-    {
-        $this->responseParser = $responseParser;
-    }
-
-    /**
-     * Release resources if still active
+     * Release resources if still active.
      */
     public function __destruct()
     {
@@ -54,11 +39,11 @@ public function __destruct()
     }
 
     /**
-     * Add promise to runner
+     * Add promise to runner.
      *
      * @param PromiseCore $core
      */
-    public function add(PromiseCore $core)
+    public function add(PromiseCore $core): void
     {
         foreach ($this->cores as $existed) {
             if ($existed === $core) {
@@ -75,16 +60,17 @@ public function add(PromiseCore $core)
     }
 
     /**
-     * Remove promise from runner
+     * Remove promise from runner.
      *
      * @param PromiseCore $core
      */
-    public function remove(PromiseCore $core)
+    public function remove(PromiseCore $core): void
     {
         foreach ($this->cores as $index => $existed) {
             if ($existed === $core) {
                 curl_multi_remove_handle($this->multiHandle, $core->getHandle());
                 unset($this->cores[$index]);
+
                 return;
             }
         }
@@ -95,7 +81,7 @@ public function remove(PromiseCore $core)
      *
      * @param PromiseCore|null $targetCore
      */
-    public function wait(PromiseCore $targetCore = null)
+    public function wait(?PromiseCore $targetCore = null): void
     {
         do {
             $status = curl_multi_exec($this->multiHandle, $active);
@@ -110,17 +96,7 @@ public function wait(PromiseCore $targetCore = null)
                 }
 
                 if (CURLE_OK === $info['result']) {
-                    try {
-                        $response = $this->responseParser->parse(
-                            curl_multi_getcontent($core->getHandle()),
-                            curl_getinfo($core->getHandle())
-                        );
-                        $core->fulfill($response);
-                    } catch (\Exception $e) {
-                        $core->reject(
-                            new RequestException($e->getMessage(), $core->getRequest(), $e)
-                        );
-                    }
+                    $core->fulfill();
                 } else {
                     $error = curl_error($core->getHandle());
                     $core->reject(new RequestException($error, $core->getRequest()));
@@ -142,13 +118,14 @@ public function wait(PromiseCore $targetCore = null)
      *
      * @return PromiseCore|null
      */
-    private function findCoreByHandle($handle)
+    private function findCoreByHandle($handle): ?PromiseCore
     {
         foreach ($this->cores as $core) {
             if ($core->getHandle() === $handle) {
                 return $core;
             }
         }
+
         return null;
     }
 }
diff --git a/src/PromiseCore.php b/src/PromiseCore.php
index 5420741..b58776f 100644
--- a/src/PromiseCore.php
+++ b/src/PromiseCore.php
@@ -1,5 +1,8 @@
 <?php
-namespace Http\Curl;
+
+declare(strict_types=1);
+
+namespace Http\Client\Curl;
 
 use Http\Client\Exception;
 use Http\Promise\Promise;
@@ -10,34 +13,40 @@
  * Shared promises core.
  *
  * @license http://opensource.org/licenses/MIT MIT
- *
  * @author  Михаил Красильников <m.krasilnikov@yandex.ru>
  */
 class PromiseCore
 {
     /**
-     * HTTP request
+     * HTTP request.
      *
      * @var RequestInterface
      */
     private $request;
 
     /**
-     * cURL handle
+     * cURL handle.
      *
      * @var resource
      */
     private $handle;
 
     /**
-     * Promise state
+     * Response builder.
+     *
+     * @var ResponseBuilder
+     */
+    private $responseBuilder;
+
+    /**
+     * Promise state.
      *
      * @var string
      */
     private $state;
 
     /**
-     * Exception
+     * Exception.
      *
      * @var Exception|null
      */
@@ -57,26 +66,50 @@ class PromiseCore
      */
     private $onRejected = [];
 
-    /**
-     * Received response
-     *
-     * @var ResponseInterface|null
-     */
-    private $response = null;
-
     /**
      * Create shared core.
      *
-     * @param RequestInterface $request HTTP request
-     * @param resource         $handle  cURL handle
-     */
-    public function __construct(RequestInterface $request, $handle)
-    {
-        assert('is_resource($handle)');
-        assert('get_resource_type($handle) === "curl"');
+     * @param RequestInterface     $request HTTP request.
+     * @param resource|\CurlHandle $handle cURL handle.
+     * @param ResponseBuilder      $responseBuilder Response builder.
+     *
+     * @throws \InvalidArgumentException If $handle is not a cURL resource.
+     */
+    public function __construct(
+        RequestInterface $request,
+        $handle,
+        ResponseBuilder $responseBuilder
+    ) {
+        if (PHP_MAJOR_VERSION === 7) {
+            if (!is_resource($handle)) {
+                throw new \InvalidArgumentException(
+                    sprintf(
+                        'Parameter $handle expected to be a cURL resource, %s given',
+                        gettype($handle)
+                    )
+                );
+            } elseif (get_resource_type($handle) !== 'curl') {
+                throw new \InvalidArgumentException(
+                    sprintf(
+                        'Parameter $handle expected to be a cURL resource, %s resource given',
+                        get_resource_type($handle)
+                    )
+                );
+            }
+        }
+
+        if (PHP_MAJOR_VERSION > 7 && !$handle instanceof \CurlHandle) {
+            throw new \InvalidArgumentException(
+                sprintf(
+                    'Parameter $handle expected to be a cURL resource, %s given',
+                    get_debug_type($handle)
+                )
+            );
+        }
 
         $this->request = $request;
         $this->handle = $handle;
+        $this->responseBuilder = $responseBuilder;
         $this->state = Promise::PENDING;
     }
 
@@ -85,12 +118,15 @@ public function __construct(RequestInterface $request, $handle)
      *
      * @param callable $callback
      */
-    public function addOnFulfilled(callable $callback)
+    public function addOnFulfilled(callable $callback): void
     {
         if ($this->getState() === Promise::PENDING) {
             $this->onFulfilled[] = $callback;
         } elseif ($this->getState() === Promise::FULFILLED) {
-            $this->response = call_user_func($callback, $this->response);
+            $response = call_user_func($callback, $this->responseBuilder->getResponse());
+            if ($response instanceof ResponseInterface) {
+                $this->responseBuilder->setResponse($response);
+            }
         }
     }
 
@@ -99,7 +135,7 @@ public function addOnFulfilled(callable $callback)
      *
      * @param callable $callback
      */
-    public function addOnRejected(callable $callback)
+    public function addOnRejected(callable $callback): void
     {
         if ($this->getState() === Promise::PENDING) {
             $this->onRejected[] = $callback;
@@ -109,9 +145,9 @@ public function addOnRejected(callable $callback)
     }
 
     /**
-     * Return cURL handle
+     * Return cURL handle.
      *
-     * @return resource
+     * @return resource|\CurlHandle
      */
     public function getHandle()
     {
@@ -123,17 +159,17 @@ public function getHandle()
      *
      * @return string
      */
-    public function getState()
+    public function getState(): string
     {
         return $this->state;
     }
 
     /**
-     * Return request
+     * Return request.
      *
      * @return RequestInterface
      */
-    public function getRequest()
+    public function getRequest(): RequestInterface
     {
         return $this->request;
     }
@@ -141,16 +177,11 @@ public function getRequest()
     /**
      * Return the value of the promise (fulfilled).
      *
-     * @return ResponseInterface Response Object only when the Promise is fulfilled.
-     *
-     * @throws \LogicException When the promise is not fulfilled.
+     * @return ResponseInterface Response object only when the Promise is fulfilled
      */
-    public function getResponse()
+    public function getResponse(): ResponseInterface
     {
-        if (null === $this->response) {
-            throw new \LogicException('Promise is not fulfilled');
-        }
-        return $this->response;
+        return $this->responseBuilder->getResponse();
     }
 
     /**
@@ -159,61 +190,63 @@ public function getResponse()
      * If the exception is an instance of Http\Client\Exception\HttpException it will contain
      * the response object with the status code and the http reason.
      *
-     * @return Exception Exception Object only when the Promise is rejected.
+     * @return \Throwable Exception Object only when the Promise is rejected
      *
-     * @throws \LogicException When the promise is not rejected.
+     * @throws \LogicException When the promise is not rejected
      */
-    public function getException()
+    public function getException(): \Throwable
     {
         if (null === $this->exception) {
             throw new \LogicException('Promise is not rejected');
         }
+
         return $this->exception;
     }
 
     /**
      * Fulfill promise.
-     *
-     * @param ResponseInterface $response Received response
      */
-    public function fulfill(ResponseInterface $response)
+    public function fulfill(): void
     {
-        $this->response = $response;
         $this->state = Promise::FULFILLED;
-        $this->response = $this->call($this->onFulfilled, $this->response);
+        $response = $this->responseBuilder->getResponse();
+        try {
+            $response->getBody()->seek(0);
+        } catch (\RuntimeException $e) {
+            $exception = new Exception\TransferException($e->getMessage(), $e->getCode(), $e);
+            $this->reject($exception);
+
+            return;
+        }
+
+        while (count($this->onFulfilled) > 0) {
+            $callback = array_shift($this->onFulfilled);
+            $response = call_user_func($callback, $response);
+        }
+
+        if ($response instanceof ResponseInterface) {
+            $this->responseBuilder->setResponse($response);
+        }
     }
 
     /**
      * Reject promise.
      *
-     * @param Exception $exception Reject reason.
+     * @param Exception $exception Reject reason
      */
-    public function reject(Exception $exception)
+    public function reject(Exception $exception): void
     {
         $this->exception = $exception;
         $this->state = Promise::REJECTED;
 
-        try {
-            $this->call($this->onRejected, $this->exception);
-        } catch (Exception $exception) {
-            $this->exception = $exception;
-        }
-    }
-
-    /**
-     * Call functions.
-     *
-     * @param callable[] $callbacks on fulfill or on reject callback queue
-     * @param mixed      $argument  response or exception
-     *
-     * @return mixed response or exception
-     */
-    private function call(array &$callbacks, $argument)
-    {
-        while (count($callbacks) > 0) {
-            $callback = array_shift($callbacks);
-            $argument = call_user_func($callback, $argument);
+        while (count($this->onRejected) > 0) {
+            $callback = array_shift($this->onRejected);
+            try {
+                $exception = call_user_func($callback, $this->exception);
+                $this->exception = $exception;
+            } catch (Exception $exception) {
+                $this->exception = $exception;
+            }
         }
-        return $argument;
     }
 }
diff --git a/src/ResponseBuilder.php b/src/ResponseBuilder.php
new file mode 100644
index 0000000..c7250e7
--- /dev/null
+++ b/src/ResponseBuilder.php
@@ -0,0 +1,24 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Http\Client\Curl;
+
+use Http\Message\Builder\ResponseBuilder as OriginalResponseBuilder;
+use Psr\Http\Message\ResponseInterface;
+
+/**
+ * Extended response builder.
+ */
+class ResponseBuilder extends OriginalResponseBuilder
+{
+    /**
+     * Replace response with a new instance.
+     *
+     * @param ResponseInterface $response
+     */
+    public function setResponse(ResponseInterface $response): void
+    {
+        $this->response = $response;
+    }
+}
diff --git a/src/ResponseParser.php b/src/ResponseParser.php
deleted file mode 100644
index 716ff27..0000000
--- a/src/ResponseParser.php
+++ /dev/null
@@ -1,75 +0,0 @@
-<?php
-namespace Http\Curl;
-
-use Http\Curl\Tools\HeadersParser;
-use Http\Message\MessageFactory;
-use Http\Message\StreamFactory;
-use Psr\Http\Message\ResponseInterface;
-
-/**
- * cURL raw response parser
- *
- * @license http://opensource.org/licenses/MIT MIT
- *
- * @author  Михаил Красильников <m.krasilnikov@yandex.ru>
-*/
-class ResponseParser
-{
-    /**
-     * PSR-7 message factory
-     *
-     * @var MessageFactory
-     */
-    private $messageFactory;
-
-    /**
-     * PSR-7 stream factory
-     *
-     * @var StreamFactory
-     */
-    private $streamFactory;
-
-    /**
-     * Create new parser.
-     *
-     * @param MessageFactory $messageFactory HTTP Message factory
-     * @param StreamFactory  $streamFactory  HTTP Stream factory
-     */
-    public function __construct(MessageFactory $messageFactory, StreamFactory $streamFactory)
-    {
-        $this->messageFactory = $messageFactory;
-        $this->streamFactory = $streamFactory;
-    }
-
-    /**
-     * Parse cURL response
-     *
-     * @param string $raw  raw response
-     * @param array  $info cURL response info
-     *
-     * @return ResponseInterface
-     *
-     * @throws \InvalidArgumentException
-     * @throws \RuntimeException
-     */
-    public function parse($raw, array $info)
-    {
-        $response = $this->messageFactory->createResponse();
-
-        $headerSize = $info['header_size'];
-        $rawHeaders = substr($raw, 0, $headerSize);
-
-        $parser = new HeadersParser();
-        $response = $parser->parseString($rawHeaders, $response);
-
-        /*
-         * substr can return boolean value for empty string. But createStream does not support
-         * booleans. Converting to string.
-         */
-        $content = (string) substr($raw, $headerSize);
-        $stream = $this->streamFactory->createStream($content);
-        $response = $response->withBody($stream);
-
-        return $response;
-    }
-}
diff --git a/src/Tools/HeadersParser.php b/src/Tools/HeadersParser.php
deleted file mode 100644
index a33b941..0000000
--- a/src/Tools/HeadersParser.php
+++ /dev/null
@@ -1,88 +0,0 @@
-<?php
-namespace Http\Curl\Tools;
-
-use Psr\Http\Message\ResponseInterface;
-
-/**
- * HTTP response headers parser
- */
-class HeadersParser
-{
-    /**
-     * Parse headers and write them to response object.
-     *
-     * @param string[]          $headers  Response headers as array of header lines.
-     * @param ResponseInterface $response Response to write headers to.
-     *
-     * @return ResponseInterface
-     *
-     * @throws \InvalidArgumentException For invalid status code arguments.
-     * @throws \RuntimeException
-     */
-    public function parseArray(array $headers, ResponseInterface $response)
-    {
-        $statusLine = trim(array_shift($headers));
-        $parts = explode(' ', $statusLine, 3);
-        if (count($parts) < 2 || substr(strtolower($parts[0]), 0, 5) !== 'http/') {
-            throw new \RuntimeException(
-                sprintf('"%s" is not a valid HTTP status line', $statusLine)
-            );
-        }
-
-        $reasonPhrase = count($parts) > 2 ? $parts[2] : '';
-        /** @var ResponseInterface $response */
-        $response = $response
-            ->withStatus((int) $parts[1], $reasonPhrase)
-            ->withProtocolVersion(substr($parts[0], 5));
-
-        foreach ($headers as $headerLine) {
-            $headerLine = trim($headerLine);
-            if ('' === $headerLine) {
-                continue;
-            }
-
-            $parts = explode(':', $headerLine, 2);
-            if (count($parts) !== 2) {
-                throw new \RuntimeException(
-                    sprintf('"%s" is not a valid HTTP header line', $headerLine)
-                );
-            }
-            $name = trim(urldecode($parts[0]));
-            $value = trim(urldecode($parts[1]));
-            if ($response->hasHeader($name)) {
-                $response = $response->withAddedHeader($name, $value);
-            } else {
-                $response = $response->withHeader($name, $value);
-            }
-        }
-
-        return $response;
-    }
-
-    /**
-     * Parse headers and write them to response object.
-     *
-     * @param string            $headers  Response headers as single string.
-     * @param ResponseInterface $response Response to write headers to.
-     *
-     * @return ResponseInterface
-     *
-     * @throws \InvalidArgumentException if $headers is not a string on object with __toString()
-     * @throws \RuntimeException
-     */
-    public function parseString($headers, ResponseInterface $response)
-    {
-        if (!(is_string($headers)
-            || (is_object($headers) && method_exists($headers, '__toString')))
-        ) {
-            throw new \InvalidArgumentException(
-                sprintf(
-                    '%s expects parameter 1 to be a string, %s given',
-                    __METHOD__,
-                    is_object($headers) ? get_class($headers) : gettype($headers)
-                )
-            );
-        }
-        return $this->parseArray(explode("\r\n", $headers), $response);
-    }
-}
diff --git a/tests/BaseUnitTestCase.php b/tests/BaseUnitTestCase.php
deleted file mode 100644
index 6768763..0000000
--- a/tests/BaseUnitTestCase.php
+++ /dev/null
@@ -1,72 +0,0 @@
-<?php
-namespace Http\Curl\Tests;
-
-use Http\Curl\PromiseCore;
-use Http\Discovery\MessageFactoryDiscovery;
-use Psr\Http\Message\RequestInterface;
-use Psr\Http\Message\ResponseInterface;
-
-/**
- * Base class for unit tests
- */
-abstract class BaseUnitTestCase extends \PHPUnit_Framework_TestCase
-{
-    /**
-     * Test cURL handle
-     *
-     * @var resource|null
-     */
-    protected $handle = null;
-
-    /**
-     * Tears down the fixture.
-     */
-    protected function tearDown()
-    {
-        parent::tearDown();
-        if (is_resource($this->handle)) {
-            curl_close($this->handle);
-        }
-    }
-
-    /**
-     * Create new request
-     *
-     * @param string $method
-     * @param mixed $uri
-     *
-     * @return RequestInterface
-     */
-    protected function createRequest($method, $uri)
-    {
-        return MessageFactoryDiscovery::find()->createRequest($method, $uri);
-    }
-
-    /**
-     * Create new response
-     *
-     * @return ResponseInterface
-     */
-    protected function createResponse()
-    {
-        return MessageFactoryDiscovery::find()->createResponse();
-    }
-
-    /**
-     * Create PromiseCore mock
-     *
-     * @return PromiseCore|\PHPUnit_Framework_MockObject_MockObject
-     */
-    protected function createPromiseCore()
-    {
-        $class = new \ReflectionClass(PromiseCore::class);
-        $methods = $class->getMethods(\ReflectionMethod::IS_PUBLIC);
-        foreach ($methods as &$item) {
-            $item = $item->getName();
-        }
-        unset($item);
-        $core = $this->getMockBuilder(PromiseCore::class)->disableOriginalConstructor()
-            ->setMethods($methods)->getMock();
-        return $core;
-    }
-}
diff --git a/tests/CurlHttpAsyncClientDiactorosTest.php b/tests/CurlHttpAsyncClientDiactorosTest.php
deleted file mode 100644
index 4bbe35c..0000000
--- a/tests/CurlHttpAsyncClientDiactorosTest.php
+++ /dev/null
@@ -1,23 +0,0 @@
-<?php
-namespace Http\Curl\Tests;
-
-use Http\Client\HttpClient;
-use Http\Curl\CurlHttpClient;
-use Http\Discovery\MessageFactory\DiactorosMessageFactory;
-use Http\Discovery\StreamFactory\DiactorosStreamFactory;
-use Zend\Diactoros\Request;
-use Zend\Diactoros\Response;
-
-/**
- * Tests for Http\Curl\CurlHttpClient
- */
-class CurlHttpAsyncClientDiactorosTest extends CurlHttpAsyncClientTestCase
-{
-    /**
-     * @return HttpClient
-     */
-    protected function createHttpAsyncClient()
-    {
-        return new CurlHttpClient(new DiactorosMessageFactory(), new DiactorosStreamFactory());
-    }
-}
diff --git a/tests/CurlHttpAsyncClientGuzzleTest.php b/tests/CurlHttpAsyncClientGuzzleTest.php
deleted file mode 100644
index 6f654a1..0000000
--- a/tests/CurlHttpAsyncClientGuzzleTest.php
+++ /dev/null
@@ -1,21 +0,0 @@
-<?php
-namespace Http\Curl\Tests;
-
-use Http\Client\HttpClient;
-use Http\Curl\CurlHttpClient;
-use Http\Discovery\MessageFactory\GuzzleMessageFactory;
-use Http\Discovery\StreamFactory\GuzzleStreamFactory;
-
-/**
- * Tests for Http\Curl\CurlHttpClient
- */
-class CurlHttpAsyncClientGuzzleTest extends CurlHttpAsyncClientTestCase
-{
-    /**
-     * @return HttpClient
-     */
-    protected function createHttpAsyncClient()
-    {
-        return new CurlHttpClient(new GuzzleMessageFactory(), new GuzzleStreamFactory());
-    }
-}
diff --git a/tests/CurlHttpAsyncClientTestCase.php b/tests/CurlHttpAsyncClientTestCase.php
deleted file mode 100644
index aec8f91..0000000
--- a/tests/CurlHttpAsyncClientTestCase.php
+++ /dev/null
@@ -1,62 +0,0 @@
-<?php
-namespace Http\Curl\Tests;
-
-use Http\Client\Tests\HttpAsyncClientTest;
-
-/**
- * Base class for async client integration tests
- */
-abstract class CurlHttpAsyncClientTestCase extends HttpAsyncClientTest
-{
-    /**
-     * @dataProvider requestProvider
-     * @group        integration
-     */
-    public function testAsyncSendRequest($method, $uri, array $headers, $body)
-    {
-        if (defined('HHVM_VERSION')) {
-            static::markTestSkipped('This test can not run under HHVM');
-        }
-        if (null !== $body && !in_array($method, ['OPTIONS', 'POST', 'PUT'], true)) {
-            static::markTestSkipped('cURL can not send body using ' . $method);
-        }
-        parent::testAsyncSendRequest(
-            $method,
-            $uri,
-            $headers,
-            $body
-        );
-    }
-
-    /**
-     * @dataProvider requestWithOutcomeProvider
-     * @group        integration
-     */
-    public function testSendAsyncRequestWithOutcome(
-        $uriAndOutcome,
-        $protocolVersion,
-        array $headers,
-        $body
-    ) {
-        if (defined('HHVM_VERSION')) {
-            static::markTestSkipped('This test can not run under HHVM');
-        }
-        if (null !== $body) {
-            static::markTestSkipped('cURL can not send body using GET');
-        }
-        parent::testSendAsyncRequestWithOutcome(
-            $uriAndOutcome,
-            $protocolVersion,
-            $headers,
-            $body
-        );
-    }
-
-    public function testSuccessiveCallMustUseResponseInterface()
-    {
-        if (defined('HHVM_VERSION')) {
-            static::markTestSkipped('This test can not run under HHVM');
-        }
-        parent::testSuccessiveCallMustUseResponseInterface();
-    }
-}
diff --git a/tests/CurlHttpClientDiactorosTest.php b/tests/CurlHttpClientDiactorosTest.php
deleted file mode 100644
index ba214dc..0000000
--- a/tests/CurlHttpClientDiactorosTest.php
+++ /dev/null
@@ -1,23 +0,0 @@
-<?php
-namespace Http\Curl\Tests;
-
-use Http\Client\HttpClient;
-use Http\Curl\CurlHttpClient;
-use Http\Discovery\MessageFactory\DiactorosMessageFactory;
-use Http\Discovery\StreamFactory\DiactorosStreamFactory;
-use Zend\Diactoros\Request;
-use Zend\Diactoros\Response;
-
-/**
- * Tests for Http\Curl\CurlHttpClient
- */
-class CurlHttpClientDiactorosTest extends CurlHttpClientTestCase
-{
-    /**
-     * @return HttpClient
-     */
-    protected function createHttpAdapter()
-    {
-        return new CurlHttpClient(new DiactorosMessageFactory(), new DiactorosStreamFactory());
-    }
-}
diff --git a/tests/CurlHttpClientGuzzleTest.php b/tests/CurlHttpClientGuzzleTest.php
deleted file mode 100644
index 9800c90..0000000
--- a/tests/CurlHttpClientGuzzleTest.php
+++ /dev/null
@@ -1,21 +0,0 @@
-<?php
-namespace Http\Curl\Tests;
-
-use Http\Client\HttpClient;
-use Http\Curl\CurlHttpClient;
-use Http\Discovery\MessageFactory\GuzzleMessageFactory;
-use Http\Discovery\StreamFactory\GuzzleStreamFactory;
-
-/**
- * Tests for Http\Curl\CurlHttpClient
- */
-class CurlHttpClientGuzzleTest extends CurlHttpClientTestCase
-{
-    /**
-     * @return HttpClient
-     */
-    protected function createHttpAdapter()
-    {
-        return new CurlHttpClient(new GuzzleMessageFactory(), new GuzzleStreamFactory());
-    }
-}
diff --git a/tests/CurlHttpClientTestCase.php b/tests/CurlHttpClientTestCase.php
deleted file mode 100644
index 2c5ef40..0000000
--- a/tests/CurlHttpClientTestCase.php
+++ /dev/null
@@ -1,54 +0,0 @@
-<?php
-namespace Http\Curl\Tests;
-
-use Http\Client\Tests\HttpClientTest;
-
-/**
- * Base class for client integration tests
- */
-abstract class CurlHttpClientTestCase extends HttpClientTest
-{
-    /**
-     * @dataProvider requestProvider
-     * @group        integration
-     */
-    public function testSendRequest($method, $uri, array $headers, $body)
-    {
-        if (defined('HHVM_VERSION')) {
-            static::markTestSkipped('This test can not run under HHVM');
-        }
-        if (null !== $body && !in_array($method, ['OPTIONS', 'POST', 'PUT'], true)) {
-            static::markTestSkipped('cURL can not send body using ' . $method);
-        }
-        parent::testSendRequest(
-            $method,
-            $uri,
-            $headers,
-            $body
-        );
-    }
-
-    /**
-     * @dataProvider requestWithOutcomeProvider
-     * @group        integration
-     */
-    public function testSendRequestWithOutcome(
-        $uriAndOutcome,
-        $protocolVersion,
-        array $headers,
-        $body
-    ) {
-        if (defined('HHVM_VERSION')) {
-            static::markTestSkipped('This test can not run under HHVM');
-        }
-        if (null !== $body) {
-            static::markTestSkipped('cURL can not send body using GET');
-        }
-        parent::testSendRequestWithOutcome(
-            $uriAndOutcome,
-            $protocolVersion,
-            $headers,
-            $body
-        );
-    }
-}
diff --git a/tests/CurlPromiseTest.php b/tests/CurlPromiseTest.php
deleted file mode 100644
index 69da729..0000000
--- a/tests/CurlPromiseTest.php
+++ /dev/null
@@ -1,72 +0,0 @@
-<?php
-namespace Http\Curl\Tests;
-
-use Http\Client\Exception\TransferException;
-use Http\Promise\Promise;
-use Http\Curl\CurlPromise;
-use Http\Curl\MultiRunner;
-
-/**
- * Tests for Http\Curl\CurlPromise
- *
- * @covers Http\Curl\CurlPromise
- */
-class CurlPromiseTest extends BaseUnitTestCase
-{
-    /**
-     * Test that promise call core methods
-     */
-    public function testCoreCalls()
-    {
-        $core = $this->createPromiseCore();
-        $runner = $this->getMockBuilder(MultiRunner::class)->disableOriginalConstructor()
-            ->setMethods(['wait'])->getMock();
-        /** @var MultiRunner|\PHPUnit_Framework_MockObject_MockObject $runner */
-        $promise = new CurlPromise($core, $runner);
-
-        $onFulfill = function () {
-        };
-        $core->expects(static::once())->method('addOnFulfilled')->with($onFulfill);
-        $onReject = function () {
-        };
-        $core->expects(static::once())->method('addOnRejected')->with($onReject);
-        $value = $promise->then($onFulfill, $onReject);
-        static::assertInstanceOf(Promise::class, $value);
-
-        $core->expects(static::once())->method('getState')->willReturn('STATE');
-        static::assertEquals('STATE', $promise->getState());
-    }
-
-    public function testCoreCallWaitFulfilled()
-    {
-        $core = $this->createPromiseCore();
-        $runner = $this->getMockBuilder(MultiRunner::class)->disableOriginalConstructor()
-            ->setMethods(['wait'])->getMock();
-        /** @var MultiRunner|\PHPUnit_Framework_MockObject_MockObject $runner */
-        $promise = new CurlPromise($core, $runner);
-
-        $runner->expects(static::once())->method('wait')->with($core);
-        $core->expects(static::once())->method('getState')->willReturn(Promise::FULFILLED);
-        $core->expects(static::once())->method('getResponse')->willReturn('RESPONSE');
-        static::assertEquals('RESPONSE', $promise->wait());
-    }
-
-    public function testCoreCallWaitRejected()
-    {
-        $core = $this->createPromiseCore();
-        $runner = $this->getMockBuilder(MultiRunner::class)->disableOriginalConstructor()
-            ->setMethods(['wait'])->getMock();
-        /** @var MultiRunner|\PHPUnit_Framework_MockObject_MockObject $runner */
-        $promise = new CurlPromise($core, $runner);
-
-        $runner->expects(static::once())->method('wait')->with($core);
-        $core->expects(static::once())->method('getState')->willReturn(Promise::REJECTED);
-        $core->expects(static::once())->method('getException')->willReturn(new TransferException());
-
-        try {
-            $promise->wait();
-        } catch (TransferException $exception) {
-            static::assertTrue(true);
-        }
-    }
-}
diff --git a/tests/Functional/HttpAsyncClientDiactorosTest.php b/tests/Functional/HttpAsyncClientDiactorosTest.php
new file mode 100644
index 0000000..c8dc1cf
--- /dev/null
+++ b/tests/Functional/HttpAsyncClientDiactorosTest.php
@@ -0,0 +1,24 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Http\Client\Curl\Tests\Functional;
+
+use Http\Client\Curl\Client;
+use Http\Client\HttpAsyncClient;
+use Laminas\Diactoros\ResponseFactory;
+use Laminas\Diactoros\StreamFactory;
+
+/**
+ * @covers \Http\Client\Curl\Client
+ */
+class HttpAsyncClientDiactorosTest extends HttpAsyncClientTestCase
+{
+    /**
+     * {@inheritdoc}
+     */
+    protected function createHttpAsyncClient(): HttpAsyncClient
+    {
+        return new Client(new ResponseFactory(), new StreamFactory());
+    }
+}
diff --git a/tests/Functional/HttpAsyncClientGuzzleTest.php b/tests/Functional/HttpAsyncClientGuzzleTest.php
new file mode 100644
index 0000000..2f6c47f
--- /dev/null
+++ b/tests/Functional/HttpAsyncClientGuzzleTest.php
@@ -0,0 +1,23 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Http\Client\Curl\Tests\Functional;
+
+use GuzzleHttp\Psr7\HttpFactory;
+use Http\Client\Curl\Client;
+use Http\Client\HttpAsyncClient;
+
+/**
+ * @covers \Http\Client\Curl\Client
+ */
+class HttpAsyncClientGuzzleTest extends HttpAsyncClientTestCase
+{
+    /**
+     * {@inheritdoc}
+     */
+    protected function createHttpAsyncClient(): HttpAsyncClient
+    {
+        return new Client(new HttpFactory(), new HttpFactory());
+    }
+}
diff --git a/tests/Functional/HttpAsyncClientTestCase.php b/tests/Functional/HttpAsyncClientTestCase.php
new file mode 100644
index 0000000..ded8f72
--- /dev/null
+++ b/tests/Functional/HttpAsyncClientTestCase.php
@@ -0,0 +1,53 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Http\Client\Curl\Tests\Functional;
+
+use Http\Client\Tests\HttpAsyncClientTest;
+
+/**
+ * Base class for asynchronous functional client tests.
+ */
+abstract class HttpAsyncClientTestCase extends HttpAsyncClientTest
+{
+    /**
+     * {@inheritdoc}
+     *
+     * @dataProvider requestProvider
+     */
+    public function testAsyncSendRequest($httpMethod, $uri, array $httpHeaders, $requestBody): void
+    {
+        if ($requestBody !== null && in_array($httpMethod, ['GET', 'HEAD', 'TRACE'], true)) {
+            self::markTestSkipped('cURL can not send body using '.$httpMethod);
+        }
+        parent::testAsyncSendRequest(
+            $httpMethod,
+            $uri,
+            $httpHeaders,
+            $requestBody
+        );
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @dataProvider requestWithOutcomeProvider
+     */
+    public function testSendAsyncRequestWithOutcome(
+        $uriAndOutcome,
+        $httpVersion,
+        array $httpHeaders,
+        $requestBody
+    ): void {
+        if ( $requestBody !== null) {
+            self::markTestSkipped('cURL can not send body using GET');
+        }
+        parent::testSendAsyncRequestWithOutcome(
+            $uriAndOutcome,
+            $httpVersion,
+            $httpHeaders,
+            $requestBody
+        );
+    }
+}
diff --git a/tests/Functional/HttpClientDiactorosTest.php b/tests/Functional/HttpClientDiactorosTest.php
new file mode 100644
index 0000000..a8fd42f
--- /dev/null
+++ b/tests/Functional/HttpClientDiactorosTest.php
@@ -0,0 +1,30 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Http\Client\Curl\Tests\Functional;
+
+
+use Http\Client\Curl\Client;
+use Psr\Http\Client\ClientInterface;
+use Http\Client\HttpClient;
+use Psr\Http\Message\StreamInterface;
+use Laminas\Diactoros\ResponseFactory;
+use Laminas\Diactoros\Stream;
+use Laminas\Diactoros\StreamFactory;
+
+/**
+ * Testing synchronous requests with Laminas Diactoros factories.
+ */
+class HttpClientDiactorosTest extends HttpClientTestCase
+{
+    protected function createFileStream(string $filename): StreamInterface
+    {
+        return new Stream($filename);
+    }
+
+    protected function createHttpAdapter(): ClientInterface
+    {
+        return new Client(new ResponseFactory(), new StreamFactory());
+    }
+}
diff --git a/tests/Functional/HttpClientGuzzleTest.php b/tests/Functional/HttpClientGuzzleTest.php
new file mode 100644
index 0000000..d7cf853
--- /dev/null
+++ b/tests/Functional/HttpClientGuzzleTest.php
@@ -0,0 +1,33 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Http\Client\Curl\Tests\Functional;
+
+use GuzzleHttp\Psr7\HttpFactory;
+use GuzzleHttp\Psr7\Stream;
+use Http\Client\Curl\Client;
+use Psr\Http\Client\ClientInterface;
+use Psr\Http\Message\StreamInterface;
+
+/**
+ * @covers \Http\Client\Curl\Client
+ */
+class HttpClientGuzzleTest extends HttpClientTestCase
+{
+    /**
+     * {@inheritdoc}
+     */
+    protected function createHttpAdapter(): ClientInterface
+    {
+        return new Client(new HttpFactory(), new HttpFactory());
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    protected function createFileStream(string $filename): StreamInterface
+    {
+        return new Stream(fopen($filename, 'r'));
+    }
+}
diff --git a/tests/Functional/HttpClientTestCase.php b/tests/Functional/HttpClientTestCase.php
new file mode 100644
index 0000000..f74d6fd
--- /dev/null
+++ b/tests/Functional/HttpClientTestCase.php
@@ -0,0 +1,120 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Http\Client\Curl\Tests\Functional;
+
+use Http\Client\Tests\HttpClientTest;
+use Http\Client\Tests\PHPUnitUtility;
+use Psr\Http\Message\StreamInterface;
+
+/**
+ * Base class for functional client tests.
+ */
+abstract class HttpClientTestCase extends HttpClientTest
+{
+    /**
+     * Temporary files names created by test.
+     *
+     * @var string[]
+     */
+    protected $tmpFiles = [];
+
+    public function testSendLargeFile(): void
+    {
+        $filename = $this->createTempFile();
+        $fd = fopen($filename, 'ab');
+        $buffer = str_repeat('x', 1024);
+        for ($i = 0; $i < 2048; ++$i) {
+            fwrite($fd, $buffer);
+        }
+        fclose($fd);
+        $body = $this->createFileStream($filename);
+
+        $request = self::$messageFactory->createRequest(
+            'POST',
+            PHPUnitUtility::getUri(),
+            ['content-length' => 1024 * 2048],
+            $body
+        );
+
+        $response = $this->httpAdapter->sendRequest($request);
+        $this->assertResponse(
+            $response,
+            [
+                'body' => 'Ok',
+            ]
+        );
+
+        $request = $this->getRequest();
+        self::assertArrayHasKey('HTTP_CONTENT_LENGTH', $request['SERVER']);
+        self::assertEquals($body->getSize(), $request['SERVER']['HTTP_CONTENT_LENGTH']);
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @dataProvider requestProvider
+     */
+    public function testSendRequest($httpMethod, $uri, array $httpHeaders, $requestBody): void
+    {
+        if ($requestBody !== null && in_array($httpMethod, ['GET', 'HEAD', 'TRACE'], true)) {
+            self::markTestSkipped('cURL can not send body using '.$httpMethod);
+        }
+        parent::testSendRequest(
+            $httpMethod,
+            $uri,
+            $httpHeaders,
+            $requestBody
+        );
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @dataProvider requestWithOutcomeProvider
+     */
+    public function testSendRequestWithOutcome(
+        $uriAndOutcome,
+        $httpVersion,
+        array $httpHeaders,
+        $requestBody
+    ): void {
+        if ($requestBody !== null) {
+            self::markTestSkipped('cURL can not send body using GET');
+        }
+        parent::testSendRequestWithOutcome(
+            $uriAndOutcome,
+            $httpVersion,
+            $httpHeaders,
+            $requestBody
+        );
+    }
+
+    abstract protected function createFileStream(string $filename): StreamInterface;
+
+    /**
+     * Create temporary file.
+     *
+     * @return string Filename
+     */
+    protected function createTempFile(): string
+    {
+        $filename = tempnam(sys_get_temp_dir(), 'tests');
+        $this->tmpFiles[] = $filename;
+
+        return $filename;
+    }
+
+    /**
+     * Delete files created with createTempFile
+     */
+    protected function tearDown(): void
+    {
+        parent::tearDown();
+
+        foreach ($this->tmpFiles as $filename) {
+            @unlink($filename);
+        }
+    }
+}
diff --git a/tests/PromiseCoreTest.php b/tests/PromiseCoreTest.php
deleted file mode 100644
index ecc67d3..0000000
--- a/tests/PromiseCoreTest.php
+++ /dev/null
@@ -1,99 +0,0 @@
-<?php
-namespace Http\Curl\Tests;
-
-use Http\Client\Exception;
-use Http\Client\Exception\RequestException;
-use Http\Promise\Promise;
-use Http\Curl\PromiseCore;
-use Psr\Http\Message\ResponseInterface;
-
-/**
- * Tests for Http\Curl\PromiseCore
- *
- * @covers Http\Curl\PromiseCore
- */
-class PromiseCoreTest extends BaseUnitTestCase
-{
-    /**
-     * Test on fulfill actions
-     */
-    public function testOnFulfill()
-    {
-        $request = $this->createRequest('GET', '/');
-        $this->handle = curl_init();
-
-        $core = new PromiseCore($request, $this->handle);
-        static::assertSame($request, $core->getRequest());
-        static::assertSame($this->handle, $core->getHandle());
-
-        $core->addOnFulfilled(
-            function (ResponseInterface $response) {
-                return $response->withAddedHeader('X-Test', 'foo');
-            }
-        );
-
-        $core->fulfill($this->createResponse());
-        static::assertEquals(Promise::FULFILLED, $core->getState());
-        static::assertInstanceOf(ResponseInterface::class, $core->getResponse());
-        static::assertEquals('foo', $core->getResponse()->getHeaderLine('X-Test'));
-
-        $core->addOnFulfilled(
-            function (ResponseInterface $response) {
-                return $response->withAddedHeader('X-Test', 'bar');
-            }
-        );
-        static::assertEquals('foo, bar', $core->getResponse()->getHeaderLine('X-Test'));
-    }
-
-    /**
-     * Test on reject actions
-     */
-    public function testOnReject()
-    {
-        $request = $this->createRequest('GET', '/');
-        $this->handle = curl_init();
-
-        $core = new PromiseCore($request, $this->handle);
-        $core->addOnRejected(
-            function (RequestException $exception) {
-                throw new RequestException('Foo', $exception->getRequest(), $exception);
-            }
-        );
-
-        $exception = new RequestException('Error', $request);
-        $core->reject($exception);
-        static::assertEquals(Promise::REJECTED, $core->getState());
-        static::assertInstanceOf(Exception::class, $core->getException());
-        static::assertEquals('Foo', $core->getException()->getMessage());
-
-        $core->addOnRejected(
-            function (RequestException $exception) {
-                return new RequestException('Bar', $exception->getRequest(), $exception);
-            }
-        );
-        static::assertEquals('Bar', $core->getException()->getMessage());
-    }
-
-    /**
-     * @expectedException \LogicException
-     */
-    public function testNotFulfilled()
-    {
-        $request = $this->createRequest('GET', '/');
-        $this->handle = curl_init();
-        $core = new PromiseCore($request, $this->handle);
-        $core->getResponse();
-    }
-
-
-    /**
-     * @expectedException \LogicException
-     */
-    public function testNotRejected()
-    {
-        $request = $this->createRequest('GET', '/');
-        $this->handle = curl_init();
-        $core = new PromiseCore($request, $this->handle);
-        $core->getException();
-    }
-}
diff --git a/tests/Tools/HeadersParserTest.php b/tests/Tools/HeadersParserTest.php
deleted file mode 100644
index efd1e08..0000000
--- a/tests/Tools/HeadersParserTest.php
+++ /dev/null
@@ -1,66 +0,0 @@
-<?php
-namespace Http\Curl\Tests\Tools;
-
-use Http\Curl\Tools\HeadersParser;
-use Http\Discovery\MessageFactoryDiscovery;
-
-/**
- * @covers Http\Curl\Tools\HeadersParser
- */
-class HeadersParserTest extends \PHPUnit_Framework_TestCase
-{
-    /**
-     * Test valid headers parsing
-     */
-    public function testValidHeaders()
-    {
-        $headers = file_get_contents(__DIR__ . '/data/headers_valid.http');
-        $response = MessageFactoryDiscovery::find()->createResponse();
-        $parser = new HeadersParser();
-        $response = $parser->parseString($headers, $response);
-        static::assertEquals(200, $response->getStatusCode());
-        static::assertEquals('OK', $response->getReasonPhrase());
-        static::assertEquals('text/html; charset=UTF-8', $response->getHeaderLine('Content-Type'));
-        static::assertEquals(['foo=1234', 'bar=4321'], $response->getHeader('Set-Cookie'));
-    }
-
-    /**
-     * Test parsing headers with invalid status line
-     *
-     * @expectedException \RuntimeException
-     * @expectedExceptionMessage "HTTP/1.1" is not a valid HTTP status line
-     */
-    public function testInvalidStatusLine()
-    {
-        $headers = file_get_contents(__DIR__ . '/data/headers_invalid_status.http');
-        $response = MessageFactoryDiscovery::find()->createResponse();
-        $parser = new HeadersParser();
-        $parser->parseString($headers, $response);
-    }
-
-    /**
-     * Test parsing headers with invalid header line
-     *
-     * @expectedException \RuntimeException
-     * @expectedExceptionMessage "Content-Type text/html" is not a valid HTTP header line
-     */
-    public function testInvalidHeaderLine()
-    {
-        $headers = file_get_contents(__DIR__ . '/data/headers_invalid_header.http');
-        $response = MessageFactoryDiscovery::find()->createResponse();
-        $parser = new HeadersParser();
-        $parser->parseString($headers, $response);
-    }
-
-
-    /**
-     * @expectedException \InvalidArgumentException
-     * @expectedExceptionMessage HeadersParser::parseString expects parameter 1 to be a string, array given
-     */
-    public function testInvalidArgument()
-    {
-        $response = MessageFactoryDiscovery::find()->createResponse();
-        $parser = new HeadersParser();
-        $parser->parseString([], $response);
-    }
-}
diff --git a/tests/Tools/data/headers_invalid_header.http b/tests/Tools/data/headers_invalid_header.http
deleted file mode 100644
index cbfa1e8..0000000
--- a/tests/Tools/data/headers_invalid_header.http
+++ /dev/null
@@ -1,2 +0,0 @@
-HTTP/1.1 200 OK
-Content-Type text/html
diff --git a/tests/Tools/data/headers_invalid_status.http b/tests/Tools/data/headers_invalid_status.http
deleted file mode 100644
index 4bea2bb..0000000
--- a/tests/Tools/data/headers_invalid_status.http
+++ /dev/null
@@ -1,4 +0,0 @@
-HTTP/1.1
-Content-Type: text/html; charset=UTF-8
-Set-Cookie: foo=1234
-Set-Cookie: bar=4321
diff --git a/tests/Tools/data/headers_valid.http b/tests/Tools/data/headers_valid.http
deleted file mode 100644
index b3b5536..0000000
--- a/tests/Tools/data/headers_valid.http
+++ /dev/null
@@ -1,4 +0,0 @@
-HTTP/1.1 200 OK
-Content-Type: text/html; charset=UTF-8
-Set-Cookie: foo=1234
-Set-Cookie: bar=4321
diff --git a/tests/Unit/ClientTest.php b/tests/Unit/ClientTest.php
new file mode 100644
index 0000000..55d3e89
--- /dev/null
+++ b/tests/Unit/ClientTest.php
@@ -0,0 +1,111 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Http\Client\Curl\Tests\Unit;
+
+use GuzzleHttp\Psr7\Utils;
+use Http\Client\Curl\Client;
+use PHPUnit\Framework\TestCase;
+use Psr\Http\Message\ResponseFactoryInterface;
+use Psr\Http\Message\StreamFactoryInterface;
+use Symfony\Component\OptionsResolver\Exception\InvalidOptionsException;
+use Laminas\Diactoros\Request;
+
+/**
+ * @covers \Http\Client\Curl\Client
+ */
+class ClientTest extends TestCase
+{
+    /**
+     * Tests throwing InvalidArgumentException when invalid cURL options passed to constructor.
+     */
+    public function testExceptionThrownOnInvalidCurlOptions(): void
+    {
+        $this->expectException(InvalidOptionsException::class);
+        new Client(
+            $this->createMock(ResponseFactoryInterface::class),
+            $this->createMock(StreamFactoryInterface::class),
+            [
+                CURLOPT_HEADER => true, // this won't work with our client
+            ]
+        );
+    }
+
+    /**
+     * "Expect" header should be empty by default.
+     *
+     * @link https://github.com/php-http/curl-client/issues/18
+     */
+    public function testExpectHeaderIsEmpty(): void
+    {
+        $client = $this->createMock(Client::class);
+
+        $createHeaders = new \ReflectionMethod(Client::class, 'createHeaders');
+        $createHeaders->setAccessible(true);
+
+        $request = new Request();
+
+        $headers = $createHeaders->invoke($client, $request, []);
+
+        static::assertContains('Expect:', $headers);
+    }
+
+    /**
+     * "Expect" header should be empty when POST field is empty.
+     *
+     * @link https://github.com/php-http/curl-client/issues/18
+     */
+    public function testExpectHeaderIsEmpty2(): void
+    {
+        $client = $this->createMock(Client::class);
+
+        $createHeaders = new \ReflectionMethod(Client::class, 'createHeaders');
+        $createHeaders->setAccessible(true);
+
+        $request = new Request();
+        $request = $request->withHeader('content-length', '0');
+
+        $headers = $createHeaders->invoke($client, $request, [CURLOPT_POSTFIELDS => '']);
+
+        self::assertContains('content-length: 0', $headers);
+    }
+
+    public function testRewindLargeStream(): void
+    {
+        $client = $this->createMock(Client::class);
+
+        $bodyOptions = new \ReflectionMethod(Client::class, 'addRequestBodyOptions');
+        $bodyOptions->setAccessible(true);
+
+        $content = 'abcdef';
+        while (strlen($content) < 1024 * 1024 + 100) {
+            $content .= '123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890';
+        }
+
+        $length = strlen($content);
+        $body = Utils::streamFor($content);
+        $body->seek(40);
+        $request = new Request('http://foo.com', 'POST', $body);
+        $options = $bodyOptions->invoke($client, $request, []);
+
+        static::assertNotFalse(
+            strpos($options[CURLOPT_READFUNCTION](null, null, $length), 'abcdef'), 'Steam was not rewinded'
+        );
+    }
+
+    public function testRewindStream(): void
+    {
+        $client = $this->createMock(Client::class);
+
+        $bodyOptions = new \ReflectionMethod(Client::class, 'addRequestBodyOptions');
+        $bodyOptions->setAccessible(true);
+
+        $body = Utils::streamFor('abcdef');
+        $body->seek(3);
+        $request = new Request('http://foo.com', 'POST', $body);
+        $options = $bodyOptions->invoke($client, $request, []);
+
+        static::assertEquals('abcdef', $options[CURLOPT_POSTFIELDS]);
+    }
+}
diff --git a/tests/Unit/CurlPromiseTest.php b/tests/Unit/CurlPromiseTest.php
new file mode 100644
index 0000000..617b258
--- /dev/null
+++ b/tests/Unit/CurlPromiseTest.php
@@ -0,0 +1,75 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Http\Client\Curl\Tests\Unit;
+
+use Http\Client\Curl\CurlPromise;
+use Http\Client\Curl\MultiRunner;
+use Http\Client\Curl\PromiseCore;
+use Http\Client\Exception\TransferException;
+use Http\Promise\Promise;
+use PHPUnit\Framework\TestCase;
+use Psr\Http\Message\ResponseInterface;
+
+/**
+ * @covers \Http\Client\Curl\CurlPromise
+ */
+class CurlPromiseTest extends TestCase
+{
+    public function testCoreCallWaitFulfilled(): void
+    {
+        $core = $this->createMock(PromiseCore::class);
+        $runner = $this->getMockBuilder(MultiRunner::class)->disableOriginalConstructor()
+            ->setMethods(['wait'])->getMock();
+        /** @var MultiRunner|\PHPUnit_Framework_MockObject_MockObject $runner */
+        $promise = new CurlPromise($core, $runner);
+
+        $runner->expects(self::once())->method('wait')->with($core);
+        $core->expects(self::once())->method('getState')->willReturn(Promise::FULFILLED);
+
+        $response = $this->createMock(ResponseInterface::class);
+        $core->expects(self::once())->method('getResponse')->willReturn($response);
+        self::assertSame($response, $promise->wait());
+    }
+
+    public function testCoreCallWaitRejected(): void
+    {
+        $core = $this->createMock(PromiseCore::class);
+        $runner = $this->getMockBuilder(MultiRunner::class)->disableOriginalConstructor()->getMock();
+        /** @var MultiRunner|\PHPUnit_Framework_MockObject_MockObject $runner */
+        $promise = new CurlPromise($core, $runner);
+
+        $runner->expects(self::once())->method('wait')->with($core);
+        $core->expects(self::once())->method('getState')->willReturn(Promise::REJECTED);
+        $core->expects(self::once())->method('getException')->willReturn(new TransferException());
+
+        try {
+            $promise->wait();
+        } catch (TransferException $exception) {
+            self::assertTrue(true);
+        }
+    }
+
+    public function testCoreCalls(): void
+    {
+        $core = $this->createMock(PromiseCore::class);
+        $runner = $this->getMockBuilder(MultiRunner::class)->disableOriginalConstructor()
+            ->setMethods(['wait'])->getMock();
+        /** @var MultiRunner|\PHPUnit_Framework_MockObject_MockObject $runner */
+        $promise = new CurlPromise($core, $runner);
+
+        $onFulfill = function () {
+        };
+        $core->expects(self::once())->method('addOnFulfilled')->with($onFulfill);
+
+        $onReject = function () {
+        };
+        $core->expects(self::once())->method('addOnRejected')->with($onReject);
+
+        $promise->then($onFulfill, $onReject);
+
+        $core->expects(self::once())->method('getState')->willReturn('STATE');
+        self::assertEquals('STATE', $promise->getState());
+    }
+}
diff --git a/tests/Unit/PromiseCoreTest.php b/tests/Unit/PromiseCoreTest.php
new file mode 100644
index 0000000..7374640
--- /dev/null
+++ b/tests/Unit/PromiseCoreTest.php
@@ -0,0 +1,171 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Http\Client\Curl\Tests\Unit;
+
+use Http\Client\Curl\PromiseCore;
+use Http\Client\Curl\ResponseBuilder;
+use Http\Client\Exception;
+use Http\Client\Exception\RequestException;
+use Http\Promise\Promise;
+use PHPUnit\Framework\MockObject\MockObject;
+use PHPUnit\Framework\TestCase;
+use Psr\Http\Message\RequestInterface;
+use Psr\Http\Message\ResponseInterface;
+use Psr\Http\Message\StreamInterface;
+
+/**
+ * @covers \Http\Client\Curl\PromiseCore
+ */
+class PromiseCoreTest extends TestCase
+{
+    /**
+     * Test cURL handle.
+     *
+     * @var resource|null
+     */
+    private $handle;
+
+    /**
+     * Testing if handle is not a cURL resource.
+     */
+    public function testHandleIsNotACurlResource(): void
+    {
+        $request = $this->createMock(RequestInterface::class);
+        $responseBuilder = $this->createMock(ResponseBuilder::class);
+
+        $this->expectException(\InvalidArgumentException::class);
+        if (PHP_MAJOR_VERSION > 7) {
+            $this->expectExceptionMessage('Parameter $handle expected to be a cURL resource, resource (stream) given');
+        } else {
+            $this->expectExceptionMessage('Parameter $handle expected to be a cURL resource, stream resource given');
+        }
+
+        new PromiseCore($request, fopen('php://memory', 'r+b'), $responseBuilder);
+    }
+
+    /**
+     * Testing if handle is not a resource.
+     */
+    public function testHandleIsNotAResource(): void
+    {
+        $request = $this->createMock(RequestInterface::class);
+        $responseBuilder = $this->createMock(ResponseBuilder::class);
+
+        $this->expectException(\InvalidArgumentException::class);
+        if (PHP_MAJOR_VERSION > 7) {
+            $this->expectExceptionMessage('Parameter $handle expected to be a cURL resource, null given');
+        } else {
+            $this->expectExceptionMessage('Parameter $handle expected to be a cURL resource, NULL given');
+        }
+
+        new PromiseCore($request, null, $responseBuilder);
+    }
+
+    /**
+     * «onReject» callback can throw exception.
+     *
+     * @see https://github.com/php-http/curl-client/issues/26
+     */
+    public function testIssue26(): void
+    {
+        $request = $this->createMock(RequestInterface::class);
+        $responseBuilder = $this->createMock(ResponseBuilder::class);
+
+        $this->handle = curl_init();
+
+        $core = new PromiseCore($request, $this->handle, $responseBuilder);
+        $core->addOnRejected(
+            function (RequestException $exception) {
+                throw new RequestException('Foo', $exception->getRequest(), $exception);
+            }
+        );
+        $core->addOnRejected(
+            function (RequestException $exception) {
+                return new RequestException('Bar', $exception->getRequest(), $exception);
+            }
+        );
+
+        $exception = new RequestException('Error', $request);
+        $core->reject($exception);
+        self::assertEquals(Promise::REJECTED, $core->getState());
+        self::assertEquals('Bar', $core->getException()->getMessage());
+    }
+
+    public function testNotRejected(): void
+    {
+        $request = $this->createMock(RequestInterface::class);
+        $responseBuilder = $this->createMock(ResponseBuilder::class);
+
+        $this->handle = curl_init();
+
+        $core = new PromiseCore($request, $this->handle, $responseBuilder);
+        $this->expectException(\LogicException::class);
+        $core->getException();
+    }
+
+    public function testOnFulfill(): void
+    {
+        $request = $this->createMock(RequestInterface::class);
+
+        $stream = $this->createMock(StreamInterface::class);
+        $response1 = $this->createConfiguredMock(ResponseInterface::class, ['getBody' => $stream]);
+        $responseBuilder = $this->createConfiguredMock(ResponseBuilder::class, ['getResponse' => $response1]);
+        $response2 = $this->createConfiguredMock(ResponseInterface::class, ['getBody' => $stream]);
+
+        $this->handle = curl_init();
+
+        $core = new PromiseCore($request, $this->handle, $responseBuilder);
+
+        self::assertSame($request, $core->getRequest());
+        self::assertSame($this->handle, $core->getHandle());
+
+        $core->addOnFulfilled(
+            function (ResponseInterface $response) use ($response1, $response2) {
+                self::assertSame($response1, $response);
+
+                return $response2;
+            }
+        );
+
+        $core->fulfill();
+        self::assertEquals(Promise::FULFILLED, $core->getState());
+    }
+
+    public function testOnReject(): void
+    {
+        $request = $this->createMock(RequestInterface::class);
+        $responseBuilder = $this->createMock(ResponseBuilder::class);
+
+        $this->handle = curl_init();
+
+        $core = new PromiseCore($request, $this->handle, $responseBuilder);
+        $core->addOnRejected(
+            function (RequestException $exception) {
+                throw new RequestException('Foo', $exception->getRequest(), $exception);
+            }
+        );
+
+        $exception = new RequestException('Error', $request);
+        $core->reject($exception);
+        self::assertEquals(Promise::REJECTED, $core->getState());
+        self::assertEquals('Foo', $core->getException()->getMessage());
+
+        $core->addOnRejected(
+            function (RequestException $exception) {
+                return new RequestException('Bar', $exception->getRequest(), $exception);
+            }
+        );
+        self::assertEquals('Bar', $core->getException()->getMessage());
+    }
+
+    protected function tearDown(): void
+    {
+        if (is_resource($this->handle)) {
+            curl_close($this->handle);
+        }
+
+        parent::tearDown();
+    }
+}
diff --git a/tests/bootstrap.php b/tests/bootstrap.php
new file mode 100644
index 0000000..21696b8
--- /dev/null
+++ b/tests/bootstrap.php
@@ -0,0 +1,10 @@
+<?php
+
+$loader = require __DIR__.'/../vendor/autoload.php';
+
+// Temporary fix for Puli
+$loader->addClassMap(
+    [
+        'Puli\\GeneratedPuliFactory' => __DIR__.'/../.puli/GeneratedPuliFactory.php',
+    ]
+);