diff --git a/tests/diffParser.test.ts b/tests/diffParser.test.ts
new file mode 100644
index 0000000..8a69cda
--- /dev/null
+++ b/tests/diffParser.test.ts
@@ -0,0 +1,55 @@
+import { describe, expect, it } from 'vitest';
+import { DiffParser } from '../src/git/diffParser';
+
+describe('DiffParser', () => {
+  it('should parse an empty diff without error', () => {
+    const result = DiffParser.parse('', '/test/root');
+    expect(result.files).toHaveLength(0);
+    expect(result.totalFilesChanged).toBe(0);
+    expect(result.totalInsertions).toBe(0);
+    expect(result.totalDeletions).toBe(0);
+  });
+
+  it('should parse a standard unified diff with additions and deletions', () => {
+    const sampleDiff = `diff --git a/src/user.ts b/src/user.ts
+index e69de29..49e29a1 100644
+--- a/src/user.ts
++++ b/src/user.ts
+@@ -10,3 +10,5 @@ export function getUser(id: string) {
+-  return db.user.find(id);
++  const user = await db.user.findUnique({ where: { id } });
++  return user;
+ }
++export function deleteUser() {}
+`;
+
+    const result = DiffParser.parse(sampleDiff, '/workspace');
+    expect(result.files).toHaveLength(1);
+    const file = result.files[0];
+    expect(file.newPath).toBe('src/user.ts');
+    expect(file.addedLines).toEqual([10, 11, 13]);
+    expect(file.deletedLines).toEqual([10]);
+    expect(file.modifiedLineRanges).toEqual([
+      { start: 10, end: 11 },
+      { start: 13, end: 13 }
+    ]);
+  });
+
+  it('should identify new files correctly', () => {
+    const newFileDiff = `diff --git a/src/new-route.ts b/src/new-route.ts
+new file mode 100644
+index 0000000..49e29a1
+--- /dev/null
++++ b/src/new-route.ts
+@@ -0,0 +1,3 @@
++export async function GET() {
++  return Response.json({ status: 'ok' });
++}
+`;
+
+    const result = DiffParser.parse(newFileDiff, '/workspace');
+    expect(result.files).toHaveLength(1);
+    expect(result.files[0].isNew).toBe(true);
+    expect(result.files[0].addedLines).toEqual([1, 2, 3]);
+  });
+});