Closes #135

Author: sebastianbergmann

.github/workflows/ci.yaml

@@ -7,7 +7,7 @@ on:
 name: CI
 
 env:
-  COMPOSER_ROOT_VERSION: 8.0.x-dev
+  COMPOSER_ROOT_VERSION: 8.1.x-dev
   PHP_VERSION: 8.4
 
 permissions:

ChangeLog.md

@@ -2,6 +2,12 @@
 
 All notable changes are documented in this file using the [Keep a CHANGELOG](http://keepachangelog.com/) principles.
 
+## [8.1.0] - 2026-MM-DD
+
+### Added
+
+* [#135](https://github.com/sebastianbergmann/diff/issues/135): Add `$contextLines` constructor parameter on `UnifiedDiffOutputBuilder`
+
 ## [8.0.0] - 2026-02-06
 
 ### Removed
@@ -163,6 +169,7 @@ All notable changes are documented in this file using the [Keep a CHANGELOG](htt
 
 * This component is no longer supported on PHP 5.6
 
+[8.1.0]: https://github.com/sebastianbergmann/diff/compare/8.0.0...main
 [8.0.0]: https://github.com/sebastianbergmann/diff/compare/7.0...8.0.0
 [7.0.0]: https://github.com/sebastianbergmann/diff/compare/6.0.2...7.0.0
 [6.0.2]: https://github.com/sebastianbergmann/diff/compare/6.0.1...6.0.2

composer.json

@@ -45,7 +45,7 @@
     },
     "extra": {
         "branch-alias": {
-            "dev-main": "8.0-dev"
+            "dev-main": "8.1-dev"
         }
     }
 }

src/Output/UnifiedDiffOutputBuilder.php

@@ -36,14 +36,18 @@ final class UnifiedDiffOutputBuilder extends AbstractChunkOutputBuilder
     /**
      * @var positive-int
      */
-    private int $contextLines = 3;
+    private int $contextLines;
     private string $header;
     private bool $addLineNumbers;
 
-    public function __construct(string $header = "--- Original\n+++ New\n", bool $addLineNumbers = false)
+    /**
+     * @param positive-int $contextLines
+     */
+    public function __construct(string $header = "--- Original\n+++ New\n", bool $addLineNumbers = false, int $contextLines = 3)
     {
         $this->header         = $header;
         $this->addLineNumbers = $addLineNumbers;
+        $this->contextLines   = $contextLines;
     }
 
     public function getDiff(array $diff): string

tests/Output/UnifiedDiffOutputBuilderTest.php

@@ -115,4 +115,28 @@ public function testEmptyDiffProducesEmptyOutput(string $from, string $to): void
 
         $this->assertEmpty($output);
     }
+
+    public function testCustomContextLinesCanBeUsed(): void
+    {
+        $from = "line1\nline2\nline3\nline4\nline5\nline6\nline7\nline8\nline9\nline10\n";
+        $to   = "line1\nline2\nline3\nline4\nLINE5\nline6\nline7\nline8\nline9\nline10\n";
+
+        $differ3 = new Differ(new UnifiedDiffOutputBuilder('', false, 3));
+        $differ1 = new Differ(new UnifiedDiffOutputBuilder('', false, 1));
+        $differ5 = new Differ(new UnifiedDiffOutputBuilder('', false, 5));
+
+        $diff3 = $differ3->diff($from, $to);
+        $diff1 = $differ1->diff($from, $to);
+        $diff5 = $differ5->diff($from, $to);
+
+        $this->assertStringContainsString(' line2', $diff3);
+        $this->assertStringNotContainsString(' line1', $diff3);
+
+        $this->assertStringContainsString(' line4', $diff1);
+        $this->assertStringNotContainsString(' line3', $diff1);
+        $this->assertStringNotContainsString(' line7', $diff1);
+
+        $this->assertStringContainsString(' line1', $diff5);
+        $this->assertStringContainsString(' line9', $diff5);
+    }
 }