Writing Unit Tests with Jest

test.each([
  [1, 1, 2],
  [2, 2, 4],
  [3, 3, 6]
])('adds %i + %i to equal %i', (a, b, expected) => {
  expect(sum(a, b)).toBe(expected);
});

Integration testing
Snapshot testing
Parameterized testing
This shows parameterized testing: 1) Runs same test with different inputs, 2) Reduces test code duplication, 3) Tests multiple scenarios efficiently, 4) Uses table-driven test approach, 5) Improves test maintenance, 6) Makes edge cases explicit, 7) Common for testing calculations or transformations, 8) Enhances test coverage with less code.
Mock testing