test(css-dimensions-util): add actual test

src/utils/__tests__/cssDimensions.test.js

@@ -14,8 +14,10 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-import { test } from 'vitest';
+import { expect,  test } from 'vitest';
+import { ensureUnit } from '../cssDimensions';
 
 test.for([
 ])('ensureUnit returns $expected with input $dimension', ({ dimension, expected }) => {
+    expect(ensureUnit(dimension)).toBe(expected);
 });