AI Prompts for Claude for Testing

Write unit tests for this function using [JEST/VITEST/OTHER]: [PASTE FUNCTION]. Cover the happy path, edge cases, error conditions, and boundary values. Use descriptive test names.

I have this function that is hard to test because it has side effects: [PASTE FUNCTION]. Refactor it to be testable and write the tests.

Write tests for this React component: [PASTE COMPONENT]. Test: what renders initially, how it responds to user interaction, and how it handles loading and error states.

What should I actually test in this codebase? [DESCRIBE OR PASTE MODULE]. Identify the highest-value tests to write first vs what would be over-testing.

My tests are brittle — they break when I refactor even though the behavior is correct: [DESCRIBE TESTS]. Explain what is wrong and rewrite them to test behavior, not implementation.

Write an integration test for this API endpoint: [PASTE OR DESCRIBE ENDPOINT]. Test the happy path, validation errors, auth failure, and a database constraint violation.

Set up database integration tests for [DESCRIBE APP AND DATABASE]. Show the test database config, setup/teardown hooks, and two example tests that use real data.

Write a Playwright or Cypress end-to-end test for this user flow: [DESCRIBE FLOW, E.G. "USER SIGNS UP, VERIFIES EMAIL, AND COMPLETES ONBOARDING"]. Handle async steps and assertions correctly.

My integration tests are slow. Here is the current setup: [DESCRIBE]. Suggest ways to speed them up without losing coverage — parallelisation, shared fixtures, smarter setup.

How do I test third-party API integrations without hitting the real API in tests? Show me the mocking strategy for [DESCRIBE API INTEGRATION] with examples.

Explain the testing pyramid for [DESCRIBE MY APP: FRONTEND SPA / API SERVICE / FULL-STACK]. How many unit, integration, and E2E tests should I have and why?

I have no tests and need to start. Here is my codebase: [DESCRIBE]. What should I test first to get the most protection per hour of work?

My test suite has [N]% code coverage but I still have production bugs. What does coverage not tell me and what kinds of tests should I add?

Design the test strategy for [DESCRIBE NEW FEATURE]. What unit tests, integration tests, and E2E tests do I need? What can I leave untested without taking on significant risk?

Should I use [JEST / VITEST / TESTING LIBRARY / PLAYWRIGHT / CYPRESS] for [DESCRIBE PROJECT AND WHAT I NEED TO TEST]? Compare the options for my specific use case.

Review this test file and tell me what is wrong with it: [PASTE TEST FILE]. Look for: testing implementation details, over-mocking, poor test names, and missing assertions.

I have a lot of test duplication. Here is a group of similar tests: [PASTE TESTS]. Refactor them to use shared fixtures or parameterised tests without losing clarity.

My mocks are getting out of hand: [DESCRIBE MOCK SETUP]. Show me a cleaner approach that is easier to maintain and less likely to give false positives.

Write the test data factories for [DESCRIBE DOMAIN OBJECTS]. Each factory should produce valid objects with sensible defaults and allow any field to be overridden.

How do I run only the tests related to the file I just changed, and how do I set up watch mode so tests run automatically as I edit?