Goal:

Ensure the business logic of your app is airtight

✅ Unit tests cover individual units of your code.
✅  API tests cover endpoint functionality.

• Typically easy and fast to write

• Can address edge cases that are hard to replicate in production

• A lot of tests required for full application coverage

• No guarantee the individual units will work together

Goal:

Make sure the different parts of your app work together

✅ Integration tests cover the relationship between parts of your code.
✅  Contract testing covers your application’s connection to external APIs or microservices.

• Confirm important implementations function as expected

• Ensures changes in one part of the application don’t break another area

• Useful for critical functionality of the application

Goal:

Validate that components behave and render appropriately

✅ Component tests cover the components of your application, ensuring they handle different props appropriately and render as expected.

• Particularly critical for multi-use components leveraged across your application

• Relevant for modern component-based frameworks like React, Angular, and Vue

• Don't address user flows across components

Goals:

• Confirm the application looks as expected

• Ensure the application works for your user

• Prevent bugs/regressions in production

• Reduce developer time spent on debugging

• Have confidence in deployments

✅ Visual and functional end-to-end tests cover your application like a user would.

• Can achieve high application coverage with fewer tests

• Check application functionality and appearance at the same time with visual testing tools

• Keep your user happy and critical application paths working

• Modern tooling makes writing end-to-end tests faster and easier

✅ Visual and functional end-to-end tests cover your application like a user would.