Mocking

Take a thin slice of functionality and make it work end-to-end, backed by tests.

• mocking create interfaces that real code and test code can implement
• allows you to use dependency injection
• Spies are a kind of mock which can record how a dependency is used. They can record the arguments sent in, how many times it has been called, etc.
• introduce tight coupling with tests and implementation, use only if important
• favour testing expected behavior rather than the implementation
• if mocking code become complicated
• The thing you are testing is having to do too many things
• Your test is too concerned with implementation details
• a lot of mocking points to bad abstraction in your code.