Writing Unit Tests with Jest

test('matches the snapshot', () => {
  const user = generateUser();
  expect(user).toMatchSnapshot();
});

Change detection
Diff matching
Snapshot testing
Snapshot testing provides change detection: 1) Captures expected output state, 2) Compares against future test runs, 3) Detects unintended changes, 4) Useful for UI component testing, 5) Maintains output consistency, 6) Simplifies large object testing, 7) Helps catch regressions, 8) Good for testing stable interfaces.
Object comparison