Add POC test

Author: SpacePossum

tests/DifferTestTest.php

@@ -0,0 +1,83 @@
+<?php declare(strict_types=1);
+/*
+ * This file is part of sebastian/diff.
+ *
+ * (c) Sebastian Bergmann <[email protected]>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace SebastianBergmann\Diff;
+
+use PHPUnit\Framework\TestCase;
+
+/**
+ * @requires OS Linux
+ */
+final class DifferTestTest extends TestCase
+{
+    private $fileFrom;
+    private $filePatch;
+    private $fileTo;
+
+    protected function setUp()
+    {
+        $dir             = \realpath(__DIR__ . '/../') . '/';
+        $this->fileFrom  = $dir . 'from.txt';
+        $this->filePatch = $dir . 'patch.txt';
+    }
+
+    /**
+     * @dataProvider provideDiffWithLineNumbers
+     */
+    public function testTheTestProvideDiffWithLineNumbers($expected, $from, $to)
+    {
+        $this->runThisTest($expected, $from, $to);
+    }
+
+    public function provideDiffWithLineNumbers()
+    {
+        require_once __DIR__ . '/DifferTest.php';
+        $test  = new DifferTest();
+        $tests = $test->provideDiffWithLineNumbers();
+
+        $tests = \array_filter(
+            $tests,
+            function ($key) {
+                return !\is_string($key) || false === \strpos($key, 'non_patch_compat');
+            },
+            ARRAY_FILTER_USE_KEY
+        );
+
+        return $tests;
+    }
+
+    private function runThisTest(string $expected, string $from, string $to)
+    {
+        $expected = \str_replace('--- Original', '--- from.txt', $expected);
+        $expected = \str_replace('+++ New', '+++ from.txt', $expected);
+
+        @\unlink($this->fileFrom);
+        @\unlink($this->filePatch);
+
+        $this->assertNotFalse(\file_put_contents($this->fileFrom, $from));
+        $this->assertNotFalse(\file_put_contents($this->filePatch, $expected));
+
+        $command = \sprintf(
+            'patch -u --verbose %s < %s', // --posix
+            \escapeshellarg($this->fileFrom),
+            \escapeshellarg($this->filePatch)
+        );
+
+        \exec($command, $output, $d);
+
+        $this->assertSame(0, $d, \sprintf('%s | %s', $command, \implode("\n", $output)));
+
+        $patched = \file_get_contents($this->fileFrom);
+        $this->assertSame($patched, $to);
+
+        @\unlink($this->fileFrom);
+        @\unlink($this->filePatch);
+    }
+}