Arguments for Automated Testing

• Credit: Some of this is directly quoting POODR

Testing and Agile

• Notion of a ‘release’ is gone
• Notion of a ‘spec’ is gone
• Cycles are much faster
• Automation becomes a requirement

Testing and Design

• TDD supports design
• Insist on looking at the class/module/unit first as a black box that delivers services
• Good design delays all decisions that can be delayed until further requirements are nailed down.
• Refactoring is how new requirements are incorporated
• Good test suites is what gives you the confidence to refactor

Testing and Refactoring:

• Recall: Refactoring is a controlled technique for improving the design of an existing code base. Its essence is applying a series of small behavior-preserving transformations, each of which ‘too small to be worth doing’
• So you always should have solid tests before you start refactoring
• Each small change is verified to not have changed behavior

Good Testing/Quality/Testability

Fundamental motivation for testing: reduce costs

• Writing tests should over the lifetime of the code cost less
• Otherwise it’s not worth doing

Breaking it down: Why Test?

• Finding bugs early
• Reducing errors
• Making assumptions explicit - documenting code with code [how do test do that?]
• Make refactoring possible and safe [how safe?]
• Driving design decisions (TDD?)
• Discover bad design decisions [how?]