Test Generation Skill

Purpose

Create consistent, comprehensive tests.

Test Patterns

Unit Test Pattern

Reference: patterns/unit-tests.md

describe('[Unit Under Test]', () => {
  describe('[method/function]', () => {
    it('should [expected behavior] when [condition]', () => {
      // Arrange
      const input = ...;
      const expected = ...;

      // Act
      const result = functionUnderTest(input);

      // Assert
      expect(result).toEqual(expected);
    });

    it('should throw [error] when [invalid condition]', () => {
      // Arrange
      const invalidInput = ...;

      // Act & Assert
      expect(() => functionUnderTest(invalidInput))
        .toThrow(ExpectedError);
    });
  });
});

Integration Test Pattern

Reference: patterns/integration-tests.md

E2E Test Pattern

Reference: patterns/e2e-tests.md

Coverage Targets

Test Naming Convention

[should/does] [expected behavior] [when/given] [condition]

Examples:

• should return user when valid ID provided
• should throw NotFoundError when user does not exist
• should disable button when form is invalid

What to Test

• Happy path (normal operation)
• Edge cases (boundaries)
• Error cases (exceptions)
• State transitions

Test Structure

AAA Pattern

// Arrange - set up test data and conditions
const input = createTestInput();
const mockService = createMock();

// Act - execute the code under test
const result = await functionUnderTest(input);

// Assert - verify the outcome
expect(result).toEqual(expectedOutput);
expect(mockService.method).toHaveBeenCalledWith(expectedArgs);

BDD Style

describe('User Service', () => {
  describe('when creating a user', () => {
    it('should save the user to the database', () => { });
    it('should send a welcome email', () => { });
    it('should return the created user', () => { });
  });

  describe('when the email is invalid', () => {
    it('should throw a ValidationError', () => { });
  });
});

Test Template

Use: templates/test-template.ts

Best Practices

Do

• Test behavior, not implementation
• Use descriptive test names
• Keep tests independent
• Use factories for test data
• Mock external dependencies

Don't

• Test private methods directly
• Share state between tests
• Use production data in tests
• Over-mock (test should be meaningful)
• Write flaky tests

Storage Location

Save test reports to: docs/reviews/test-report-{session}.md