Unit Tests - The Three Laws of Test Driven Development

[jnguyen095]

By now everyone knows that TDD asks us to write unit tests first, before we write production code. But that rule is just the tip of the iceberg. Consider the following three laws:

1. First Law You may not write production code until you have written a failing unit test.
2. Second Law You may not write more of a unit test than is sufficient to fail, and not compiling
   is failing.
3. Third Law You may not write more production code than is sufficient to pass the currently
   failing test.