Test Driven Development

Presented by: Ryan Rapp

Overview

• What is TDD?• Refactoring• Advantages• Disadvantages• Why should I use TDD?• Conclusions

What is TDD?

• Don’t write production code without first writing a failing unit test

• Don’t write more of a test than is sufficient to fail

• Don’t write more code than is sufficient to pass the test

What is a Unit Test?

• Tests a very small section of code in isolation

• Runs every time you compile your code• Easy to read and understand• Runs very quickly• May use mock objects to avoid testing

complex interactions

Refactoring

• Take existing code and change it so that it is more efficient

• Don’t actually change the output of the code, just how it works

• May incorporate significant changes

Advantages

• Produces fully testable code• Gets running code very quickly• Design to the specifications, don’t over-

engineer

Disadvantages

• Causes people to take paths they wouldn’t otherwise

• “Write test, write code to pass test, repeat” loop is overly strict

• Most TDD shops don’t strictly adhere to it

Why should I use TDD?

• TDD makes you produce 100% testable code

• You won’t spend a long time with non-running code

• Your code will always meet the design specifications

Conclusion

• TDD isn’t for everyone• TDD is a very good design principle• TDD produces 100% tested/testable

code• End up with better software

Questions?