Santa has created a program representing his daily routine.
He would like to add tests on it but does not know how to test it. He has heard a lot of stuff regarding simulating dependencies.
Here are his findings:
Test Double: replace a component on which the Subject Under Test (SUT) depends with a "test-specific equivalent".Dummy: we pass an object that has no implementation as an argument of a method called on the SUT.Spy: double to capture the indirect output calls made to another component by the system under test (SUT) for later verification by the test.Fake: replace a component that the SUT depends on with a much lighter-weight implementation.Stub: replace a real object with a test-specific object that feeds the desired indirect inputs into the system under test.Mock: replace an object the system under test (SUT) depends on with a test-specific object that verifies it is being used correctly by the SUT.
He understood that using Test Doubles will make his tests ensure those characteristics:
Isolation: allow us to break the original dependencies by isolating the unit / System Under Test (SUT) from its collaborators.Repeatability: ensure repeatability of our tests as well by replacing external dependencies: call to an API, non deterministic data, ...Fast: keep our tests Fast.
Please write the Unit Tests for this Routine program (1 with a library and another 1 with your own fakes) to demonstrate what are Test Doubles to Santa.
✅🚀 Challenge: Demonstrate the test doubles by comparing it to using a mock library. 🚀✅
