Care must be taken to put them into a known good state before testing
Have a state
Only the interfaces and shell implementation are written before unit tests
Cause side effects
Tests component's functionality only
Have no state
Result may differ depending on what happened previously
Cause no side effects
Also known as Red/Green/Refactor
Ensures that a component does what it promises to do
the de facto standard automated unit test framework in Java
Include all static methods in Java Math class
Has good integration with Netbeans, Eclipse, IntelliJ, and Maven
Act like a math function
Used to test lowest level components of an application
Makes it easy to create unit tests suites for Java components
Is responsibility of software developer for each class they create
Each code path through a component is exercised
Always produce the same result
Test Driven Development
Takes a component's implementation into account
If any unit tests fail, the build fails
Knows nothing of the component's specific implementation
Also known as White Box Testing
Is usually done with an automated framework like JUnit
Tests the interface
Component unit tests are written before actual implementation
