Do not add additional newline to unified diff when completely empty

Author: Zach Bailey

src/Output/UnifiedDiffOutputBuilder.php

@@ -67,11 +67,11 @@ public function getDiff(array $diff): string
 
         \fclose($buffer);
 
-        // If the last char is not a linebreak: add it.
+        // If the diff is non-empty and last char is not a linebreak: add it.
         // This might happen when both the `from` and `to` do not have a trailing linebreak
         $last = \substr($diff, -1);
 
-        return "\n" !== $last && "\r" !== $last
+        return 0 !== \strlen($diff) && "\n" !== $last && "\r" !== $last
             ? $diff . "\n"
             : $diff;
     }

tests/Output/UnifiedDiffOutputBuilderTest.php

@@ -81,4 +81,28 @@ public function provideDiffWithLineNumbers(): array
     {
         return UnifiedDiffOutputBuilderDataProvider::provideDiffWithLineNumbers();
     }
+
+	/**
+	 * @param string $from
+	 * @param string $to
+	 *
+	 * @dataProvider provideStringsThatAreTheSame
+	 */
+    public function testEmptyDiffProducesEmptyOutput(string $from, string $to): void
+	{
+		$differ = new Differ(new UnifiedDiffOutputBuilder('', false));
+		$output = $differ->diff($from, $to);
+		$this->assertEmpty($output);
+	}
+
+	public function provideStringsThatAreTheSame(): array
+	{
+		return [
+			['', ''],
+			['a', 'a'],
+			['these strings are the same', 'these strings are the same'],
+			["\n", "\n"],
+			["multi-line strings\nare the same", "multi-line strings\nare the same"]
+		];
+	}
 }