diff --git a/.tests/unit/diff.test.ts b/.tests/unit/diff.test.ts
new file mode 100644
index 0000000..0cf8bda
--- /dev/null
+++ b/.tests/unit/diff.test.ts
@@ -0,0 +1,87 @@
+import { parseDiffOutput, countDiffStats } from '../../src/utils/diff-utils';
+
+describe('parseDiffOutput', () => {
+  it('should parse empty diff', () => {
+    const result = parseDiffOutput('');
+    expect(result).toEqual([]);
+  });
+
+  it('should parse diff with one file', () => {
+    const diffOutput = `diff --git a/test.ts b/test.ts
+index 1234567..89abcdef 100644
+--- a/test.ts
++++ b/test.ts
+@@ -1,3 +1,4 @@
++import { useState } from 'react';
+ function App() {
+   return <div>Hello</div>;
+ }
+@@ -5,3 +6,4 @@ function App() {
+   return <div>Hello</div>;
+ }
++// comment
+`;
+
+    const result = parseDiffOutput(diffOutput);
+    expect(result.length).toBe(1);
+    expect(result[0].file).toBe('test.ts');
+    expect(result[0].additions).toBe(2);
+    expect(result[0].deletions).toBe(0);
+  });
+
+  it('should parse diff with multiple files', () => {
+    const diffOutput = `diff --git a/file1.ts b/file1.ts
+index 1234567..89abcdef 100644
+--- a/file1.ts
++++ b/file1.ts
+@@ -1,2 +1,3 @@
++const x = 1;
+ line 1
+
+diff --git a/file2.ts b/file2.ts
+index abcdef1..2345678 100644
+--- a/file2.ts
++++ b/file2.ts
+@@ -1,2 +1,2 @@
+-old line
++new line
+ line 2
+`;
+
+    const result = parseDiffOutput(diffOutput);
+    expect(result.length).toBe(2);
+    expect(result[0].file).toBe('file1.ts');
+    expect(result[1].file).toBe('file2.ts');
+    expect(result[0].additions).toBe(1);
+    expect(result[1].additions).toBe(1);
+    expect(result[1].deletions).toBe(1);
+  });
+});
+
+describe('countDiffStats', () => {
+  it('should count additions and deletions', () => {
+    const diffContent = `diff --git a/test.ts b/test.ts
+@@ -1,3 +1,4 @@
++import { useState } from 'react';
+ function App() {
+   return <div>Hello</div>;
+ }
+@@ -5,3 +6,4 @@ function App() {
+   return <div>Hello</div>;
+ }
++// comment
+`;
+
+    const stats = countDiffStats(diffContent);
+    expect(stats.additions).toBe(2);
+    expect(stats.deletions).toBe(0);
+    expect(stats.files).toBe(1);
+  });
+
+  it('should handle empty diff', () => {
+    const stats = countDiffStats('');
+    expect(stats.additions).toBe(0);
+    expect(stats.deletions).toBe(0);
+    expect(stats.files).toBe(1);
+  });
+});