Modern C++ Programming with Test-Driven Development

Getting Green on Red

The first rule of TDD requires you to first demonstrate test failure before you can write any code. In spirit, this is a simple rule to follow. If you write only just enough code to make a test to pass, another test for additional functionality should fail automatically. In practice, however, you’ll find yourself sometimes writing tests that pass right off the bat. I refer to these undesired events as premature passes.

You might experience a premature pass for one of many reasons:

• Running the wrong tests

• Testing the wrong code

• Unfortunate test specification

• Invalid assumptions about the system

• Suboptimal test order

• Linked production code

• Overcoding

• Testing for confidence

Running the Wrong Tests

The first thing to do when sitting ...