• What is a Test Double?
  • The metaphor for Double comes from Hollywood Stunt Double.
  • Your expensive actor is exchange with your stunt double so the expensive actor doesn’t get hurt.
  • The unit under test shouldn’t realize that it isn’t talking to the collaborate object.
  • They look the same, but underneath, the test double is different.
  • The test double is completely configurable so from the test you can control what happens to the class as you test it.
  • Now a day, instead of calling test double, they are called test mock but it’s important to know that mocks are refering to something specific.

• Why use a Test Double?
• Inject Test Doubles using Monkeypatching

—This whole doubles section should be it’s own page.