diff --git a/tests/sync-version.test.js b/tests/sync-version.test.js
new file mode 100644
index 0000000..d39cbed
--- /dev/null
+++ b/tests/sync-version.test.js
@@ -0,0 +1,89 @@
+const fs = require('fs');
+const path = require('path');
+
+describe('sync-version.js', () => {
+  let consoleSpy;
+  let readFileSyncSpy;
+  let writeFileSyncSpy;
+
+  beforeEach(() => {
+    jest.resetModules();
+    consoleSpy = jest.spyOn(console, 'log').mockImplementation(() => {});
+    readFileSyncSpy = jest.spyOn(fs, 'readFileSync');
+    writeFileSyncSpy = jest.spyOn(fs, 'writeFileSync').mockImplementation(() => {});
+  });
+
+  afterEach(() => {
+    consoleSpy.mockRestore();
+    readFileSyncSpy.mockRestore();
+    writeFileSyncSpy.mockRestore();
+  });
+
+  test('updates manifest.json when versions differ', () => {
+    const packageJson = { version: '1.2.3' };
+    const manifestContent = '{\n  "version": "1.0.0",\n  "name": "test"\n}';
+
+    readFileSyncSpy.mockImplementation((filePath) => {
+      if (filePath.endsWith('package.json')) return JSON.stringify(packageJson);
+      if (filePath.endsWith('manifest.json')) return manifestContent;
+      return '{}';
+    });
+
+    require('../scripts/sync-version');
+
+    expect(writeFileSyncSpy).toHaveBeenCalledWith(
+      expect.stringContaining('manifest.json'),
+      '{\n  "version": "1.2.3",\n  "name": "test"\n}'
+    );
+    expect(consoleSpy).toHaveBeenCalledWith('Updated manifest.json version to 1.2.3');
+  });
+
+  test('does not update manifest.json when versions match', () => {
+    const packageJson = { version: '1.0.0' };
+    const manifestContent = '{\n  "version": "1.0.0",\n  "name": "test"\n}';
+
+    readFileSyncSpy.mockImplementation((filePath) => {
+      if (filePath.endsWith('package.json')) return JSON.stringify(packageJson);
+      if (filePath.endsWith('manifest.json')) return manifestContent;
+      return '{}';
+    });
+
+    require('../scripts/sync-version');
+
+    expect(writeFileSyncSpy).not.toHaveBeenCalled();
+    expect(consoleSpy).toHaveBeenCalledWith('manifest.json already matches version 1.0.0');
+  });
+
+  test('throws error if manifest.json does not contain version field', () => {
+    const packageJson = { version: '1.2.3' };
+    const manifestContent = '{\n  "name": "test"\n}';
+
+    readFileSyncSpy.mockImplementation((filePath) => {
+      if (filePath.endsWith('package.json')) return JSON.stringify(packageJson);
+      if (filePath.endsWith('manifest.json')) return manifestContent;
+      return '{}';
+    });
+
+    expect(() => {
+      require('../scripts/sync-version');
+    }).toThrow('Could not find version field in manifest.json');
+  });
+
+  test('handles different formatting in manifest.json', () => {
+    const packageJson = { version: '1.2.3' };
+    const manifestContent = '{\n"version"  :  "1.0.0",\n"name": "test"\n}';
+
+    readFileSyncSpy.mockImplementation((filePath) => {
+      if (filePath.endsWith('package.json')) return JSON.stringify(packageJson);
+      if (filePath.endsWith('manifest.json')) return manifestContent;
+      return '{}';
+    });
+
+    require('../scripts/sync-version');
+
+    expect(writeFileSyncSpy).toHaveBeenCalledWith(
+      expect.stringContaining('manifest.json'),
+      '{\n"version": "1.2.3",\n"name": "test"\n}'
+    );
+  });
+});