Refactor Tests

Contributed by: Maximiliano Contieri

Difficulty level: Intermediate

Refactoring unit tests is not just about making tests pass but about improving their structure, readability, and maintainability. Let’s look at a couple best practices when refactoring tests.

Break Down Large Tests

You should address testing code in the same way you apply these shortcuts to production code. Clean code is about simplicity and short sentences. You can refactor long tests with the same tools.

Here’s a long test in JavaScript addressing two different issues (see “Write Good Test Assertions” in this Shortcut series):

test('User can log in and see dashboard', () => {
  const user = new User('Esther Piscore');
  user.login('password123');
  expect(user.isLoggedIn()).toBe(true);

  const dashboard = user.getDashboard();
  expect(dashboard).toContain('Welcome, Esther Piscore');
});

You can refactor it in two different tests:

test('User can log in with correct credentials', () => {
  const user = new User('Esther Piscore');
  user.login('password123');
  expect(user.isLoggedIn()).toBe(true);
});

test('User sees welcome message on dashboard', () => {
  const user = new User('Esther Piscore');
  user.login('password123');
  const dashboard = user.getDashboard();
  expect(dashboard).toContain('Welcome, Esther Piscore');
});

You can also extract a common protocol like this setup in Java:

@Test
void testUserLogin() {
    User user = new User("Esther Piscore", "password123");
    user.login();
    assertTrue(user.isLoggedIn ...