group discussion

testing

who are we...

...and what are we doing here?

Goals:

create "testable" code

					TestableCode instanceof GoodCode == false
...but 
 GoodCode instanceof TestableCode == true

developer workflow

Integrating testing into the development workflow

tools

create "testable" code

Google Engineer's Guide to Writing testable code

problem: class does too much

why that’s bad:

  • Hard to debug
  • Hard to test
  • Non-extensible system
  • Difficult for new resources and hard to hand off

problem: class does too much

why that’s bad:

  • Not subject to altering behavior via standard mechanisms: decorator, strategy, subclassing: you end up adding another conditional test
  • Hard to give a name to describe what the class does. Whenever struggling with a name, the code is telling you that the responsibilities are muddled. When objects have a clear name, it is easy to keep them focused and shear off any excess baggage.

problem: class does too much

how to tell

Try to sum up what a class does in a single phrase. If this phrase includes “AND” it’s probably doing too much.

solution: class does too much

Class-responsibility-collaboration (CRC) card

"If it fits, it ships!"

solution: class does too much

Reduce Cyclomatic Complexity: Number of paths through a code base

  • Higher complexity is harder to test
  • High complexity is tied to low cohesion (degree to which the elements of a module belong together.)

problem: constructor does real work

solution: constructor does real work

Dependency Injection

Outside the scope of what we want to talk about... (but look at Spring and Guice).

moe money moe problems?

Continue to look at PDF

developer workflow

modifying workflow to encourage testing

  • start thinking about features in the context of "how do we test that??"
  • think outside the container: You don’t need to start the Web container to run code (even database code)!

developer workflow

  • business logic tests: Fast, Repeatable (automatable??)
  • database CRUD tests: Slow, Unrepeatable (non-automatable??)

tools

right tool for the right job

  • JUnit
  • Mockito/PowerMock
  • EclEmma

further discussion/moving forward

thank you!