Test Driven Developement

TDD , now a widely used jargon at almost all emerging software companys. Now what does TDD offer you? or why should you go for a TDD approach. Well.. for me...it goes this way -
Test Driven Development

• The importance of writing tests
o They force the developer to think of the class design
o They provide a safety harness while refactoring
o They ensure that the state of code is always stable
o New developers can make changes comfortable with the knowledge that if they break something that was working, the tests will inform them
o Test after development is not the same as test first development. Test after development does not reap all the benefits of test first development

• Writing the tests
o Think about the class it’s responsibilities and it’s API
o Write the tests to test every method and various conditions in the methods
o Whenever you think of writing a print statement or generate a log, it might be a scenario to include a test
o Write enough production code to ensure that the tests compile and fail
o Write production code to pass all tests one by one, while also ensuring that previous tests do not fail

• What not to test
o Database entities need not be tested
o Do not go overboard with tests. First write tests that are most likely to fail. Think of the cost benefit ratio while writing tests

• The test class
o Tests classes end with the work Test. The test class for Account will be AccountTest
o Test methods begin with the word test. The test method for creditAccount() will be testcreditAccount()
o Tests can either exist in a different source tree in the same package as the class they are testing, or in the same source tree, but in a different package.

• Managing dependencies
o Unit tests should ideally not have any dependencies
o Dependencies can be eliminated with mock objects (so that units can be tested in isolation)
• AllTests
o There should have one class AllTests that will run the entire test suite

Requirements (Java Unit Tests):
• JUnit 3.8 for JDK 1.4 and before
• JUnit 4.x for JDK 1.5 and after
• StrutsTestCase for testing Struts Action classes