From f8d43222b539aed116772c21a626e153c44ad0a5 Mon Sep 17 00:00:00 2001
From: "google-labs-jules[bot]"
 <161369871+google-labs-jules[bot]@users.noreply.github.com>
Date: Mon, 16 Feb 2026 06:04:46 +0000
Subject: [PATCH] =?UTF-8?q?=F0=9F=A7=AA=20Add=20unit=20tests=20for=20diff?=
 =?UTF-8?q?=5Fmatch=5Fpatch.diff=5FcommonPrefix?=
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Implement comprehensive unit tests for the `diff_commonPrefix` method in `DiffMatchPatch.cs`.
Scenarios covered:
- Empty strings
- No common prefix
- Complete match (identical strings)
- Partial common prefix
- One string is a prefix of another
- Case sensitivity
- Unicode support

The tests are implemented in a new file `tests/DiffMatchPatchTests.cs` using xUnit.

Co-authored-by: thezaza101 <27200279+thezaza101@users.noreply.github.com>
---
 tests/DiffMatchPatchTests.cs | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)
 create mode 100644 tests/DiffMatchPatchTests.cs

diff --git a/tests/DiffMatchPatchTests.cs b/tests/DiffMatchPatchTests.cs
new file mode 100644
index 0000000..3a3ca81
--- /dev/null
+++ b/tests/DiffMatchPatchTests.cs
@@ -0,0 +1,27 @@
+using System;
+using Xunit;
+using textdiffcore.TextDiffEngine.GoogleMyers;
+
+namespace tests
+{
+    public class DiffMatchPatchTests
+    {
+        [Theory]
+        [InlineData("", "", 0)]
+        [InlineData("abc", "", 0)]
+        [InlineData("", "abc", 0)]
+        [InlineData("abc", "abc", 3)]
+        [InlineData("abc", "abd", 2)]
+        [InlineData("abcdef", "abc", 3)]
+        [InlineData("abc", "abcdef", 3)]
+        [InlineData("ABC", "abc", 0)]
+        [InlineData("a\u0300", "a\u0300", 2)]
+        [InlineData("a\u0300", "a", 1)]
+        [InlineData("hello world", "hello friend", 6)]
+        public void TestDiffCommonPrefix(string text1, string text2, int expected)
+        {
+            var dmp = new diff_match_patch();
+            Assert.Equal(expected, dmp.diff_commonPrefix(text1, text2));
+        }
+    }
+}