PHP - Design Patterns - Test Double
What is a Test Double?
Test Double is a generic term for any case where you replace a production object for testing purposes. There are various kinds of double:
- Dummy: objects are passed around but never actually used. Usually they are just used to fill parameter lists.
- Fake: objects actually have working implementations, but usually take some shortcut which makes them not suitable for production (an InMemoryTestDatabase is a good example).
- Stubs: provide canned answers to calls made during the test, usually not responding at all to anything outside what's programmed in for the test.
- Spies: are stubs that also record some information based on how they were called. One form of this might be an email service that records how many messages it was sent.
- Mocks: are pre-programmed with expectations which form a specification of the calls they are expected to receive. They can throw an exception if they receive a call they don't expect and are checked during verification to ensure they got all the calls they were expecting.
page revision: 0, last edited: 16 Oct 2016 19:30
