Test Generation Skill Skill

Test Generation Skill

Purpose

Create consistent, comprehensive tests.

Test Patterns

Unit Test Pattern

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

| Type | Lines | Functions | Branches | |------|-------|-----------|----------| | Unit | 80% | 80% | 70% | | Integration | 60% | 60% | 50% | | E2E | Critical paths | - | - |

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

Agent Skills: Test Generation Skill

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