Skill: Fix Failing Tests

Trigger

When the user reports failing tests or asks to fix test failures.

Prerequisites

• Test command works: {{CONFIG.testing.testCommand}}
• Failing test file path or error output available
• Type check passes or run first: {{CONFIG.testing.typeCheckCommand}}

Steps

Step 1: Identify Failing Tests

• Run the test suite: {{CONFIG.testing.testCommand}}
• List all failing tests with error messages
• Categorize by failure type (assertion, timeout, mock, type)

Step 2: Analyze Each Failure

For each failing test:

• Read the error message carefully
• Check if it's a test issue or a code issue
• Look at recent changes to the tested code
• Check if mocks are correctly set up

Step 3: Common Fix Patterns

Mock Issues

• Mock not returning expected value → Update mock return
• Mock not being called → Check import path
• Mock state leaking → Add beforeEach reset

Assertion Issues

• Expected value changed → Update test or fix code
• Async not awaited → Add await or use waitFor
• Wrong matcher → Use correct Jest matcher

Type Issues

• Interface changed → Update test data
• New required field → Add to test factories
• Return type changed → Update assertions

Step 4: Fix Tests

• Fix one test at a time
• Run just that test to verify: {{CONFIG.testing.testCommand}} -- --testPathPattern={test-file}
• Ensure fix doesn't break other tests

Step 5: Verify

• Run full affected test suite
• Check coverage hasn't dropped below {{CONFIG.testing.coverageMinimum}}%
• Run type check: {{CONFIG.testing.typeCheckCommand}}

Completion Checklist

• All previously failing tests pass
• No new test failures introduced
• Coverage at or above {{CONFIG.testing.coverageMinimum}}%
• Type check passes

If Step Fails

• Step 1 (identify): Run {{CONFIG.testing.testCommand}} — if it hangs, run single file with --testPathPattern=path/to/file
• Step 2 (analyze): Mock issues often from wrong import path; use jest.mock('./path') matching actual import
• Step 4 (fix): Fix one test, run --testPathPattern to verify, then next. Don't fix all at once
• Step 5 (verify): If coverage dropped, add test for uncovered branch. Use @coverage-improvement skill

Example

Failure: "Expected 60, received undefined". Cause: mock for calculateTotal not returning. Fix: mockCalculateTotal.mockReturnValue(60) in test. Run: npm test -- order.test.ts.