The document discusses best practices for writing tests, including that tests should prove designed behaviors, focus on testing single units of code or closely collaborating classes, and be readable with short, clearly named methods that clearly indicate what is being tested and the expected result. Tests should follow guidelines like having a single concept, being short and readable, testing behaviors rather than configurations, using a build-operate-check structure, and having one assertion per test.

1. WRITING BETTER TESTS
APPLYING CLEAN-CODE LEARNINGS
@lox / 99designs

2. WHY DO WE WRITE TESTS?
• To find bugs?
• To support future refactoring and change without
regression?
• To document the system for future generations?
• Nope. Although these are awesome side-effects.

3. WHY DO WE WRITE TESTS?
• We write tests as part of the process of designing
cohesive units of code.
• Another way, tests should prove a designed
behaviour, as you are designing it.

4. WHAT MAKES A GOOD TEST?
• Orthogonality: Test one thing
• If you can’t test one class, test a few classes that
collaborate closely
• If you can’t do that, test a cohesive system as a
whole
• Mock out dependencies. If there are lots, consider
the design.

5. WHAT MAKES A GOOD TEST?
• Readability!
• Short, readable tests
• Refactor wiring into test-specific DSL’s
• Favour code over comments

6. WHAT MAKES A GOOD TEST?
• Carefully chosen names
• Test failures should clearly show what failed
• testClientThrowsExceptionOnFailedResponse 
• testClientException 
• Test methods should capture subject (Client),
scenario (Failed Response) and result (Throws
Exception).

7. GUIDELINES
• MUST have a single concept per test
• MUST be short and easy to read
• MUST test behaviour, not configuration or internals
• SHOULD follow a (build .. operate .. check) structure
• SHOULD have one assert per test
• Consider this a testing framework for your tests

8. EXAMPLE TIME!

9. QUESTIONS
• What does this test actually test?
• How does it fare on our guidelines?
• What could be improved about the test?