TDD

That Feels Great

Toby Ho   @airportyh   tobyho.com

Got 'Scripts? Test'em!

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Quick start: How to TDD

1. Write a test
2. See it fail
3. Write some code
4. See it pass
5. Refactor (optional)
6. Repeat

Why TDD?

Why TDD?

• Fewer defects
• Protect against regression
• Well designed API
• Re-use tests as specs

Where is the Pain?

• Fix a bug. Create another.
• Play pong with the QA person.
• Refactor something, break something.
• Getting stuck trying to track hard-to-find bugs.

But I Heard TDD is Painful?

Sounds like having fun at the dentist

How To TDD w/o the pain?

Good Feedback!

Good Feedback

• Fast
• Frequent
• Reliable

How To Get Good Feedback?

• Have good workflow
• Have tests finish fast
• Take small steps

Workflow Tips

• Don't use slow software
• Don't run software you don't need
• Autorun your tests on save
• Don't switch windows, tile'em
• Typing fast helps. Practice.

Having Tests Finish Fast

• Rule of thumb: < 1 second
• Favor fast tests (unit tests) to slow tests (integration tests)
• Too many tests? Break them up.
  • Run subset of tests
  • Break up into subprojects

Take Small Steps

Small Step Test Patterns

• Child tests
• Fake it 'til you make it
• One to many
• Change one thing at a time
• Back up and refactor

Live Code!

A demonstration of

small step test patterns.

Thank You!

How to do TDD

1. Write a test
2. See it fail
3. Write some code
4. See it pass
5. Refactor (optional)
6. Start again at 1