Sinon

spy

sinon.spy()

• function that records invocations
• can wrap existing methods or not
  • if wrapping an existing method, will pass through to the real implementation, and will record return value
  • if not, then there is no existing behavior to pass through to
  • seems identical to a stub in that case then
• is it related to not being able to specify return value?

stub

sinon.stub().resolves()

• superset of spies’ functionality
• spies with pre-programmed behavior
  • returns()
  • resolves()
  • throws()
  • rejects()
• can wrap existing methods or not
• but existing methods are never called

mock

• superset of stubs’ functionality
• you pre-program the expectations too

fake

pre-program behavior and make assertions. unclear how this differs from stub

sinon.fake.returns(…);
sinon.fake.resolves(…);