The TDD cycle is known as red-green-refactor. Red: write a failing test. Green: write the simplest thing that makes the test pass (initially this is just a stub). Refactor: Reduce duplication while refactoring either test-code or production-code. No behaviour changes allowed - in other words, the tests should continue to pass after this step.
A simple acronym for knowing how to test a variety of use cases within a system under test. The Acronym Stands for: Z - Zero items within the user case One - One items within the user case Many - many items within the user case B - Boundaries in the use case I - Interfaces in the use case, construct any interfaces? Never fully understood this one E - Exceptions in the use case S - This one doesn’t really mean anything, but rounds out the acronym
The general format of writing a test is given, when, then. Give a certain setup, when I call a method/series of methods, then I get some result. Often the given can get much too large, where test factories, builders, etc. can be used to reduce this. When tends to be just a single method, and the assert should be a single assert ideally - sometimes we are testing properties, however, where multiple asserts may be needed.