TDD & Unit Testing

Unit Testing means test a single unit. TDD uses unit testing to drive the design. Create the test first then write the code.

TDD refers to Red, Green, and Refactor.

• Red - Create a failed test.
• Green - Write enough to pass the test.
• Refactor - Clean up the code.

To do the test, we need to assert the expected and actual value. We can assert for:

1. Equality = AreEqual, AreNotEqual
2. Identity = AreSame, AreNotSame, Contains
3. Condition = IsTrue, IsFalse, IsNull, IsNotNull, IsNaN, IsEmpty, IsNotEmpty
4. Type = IsInstanceOf<T>, IsNotInstanceOf<T>, IsAssignableFrom<T>, ...
5. Exception = Assert.Throws ..
6. String = Contains, StartsWith, EndsWith, AreEqualIgnoringCase, IsMatch (regex)
7. Collections = AllItemsAre ... InstanceOfType, NotUnull, Unique, Equal, ..
8. File = AreEqual, AreNotEqual
9. Directory = AreEqual, AreNotEqual

When you refactoring, keep in mind that name matters.