Clean Code
Functions
A function should do one thing. DRY (Do not repeat yourself)
Output arguments
Output arguments should be avoided. If the function changes the state of something, have it change the state of its owning object.
Command query separation
- Functions should either do something or answer something but not both.
- Prefer exceptions to returning error codes.
- Extract try/catch blocks.
- Error handling is one thing.
Error handling
- Use Exceptions rather than return codes.
- Use unchecked exceptions.
- Provide context with exceptions.
- Don't return null, throw an exception instead.
Tests
- Tests should follow FIRST - Fast, Independent, Repeatable, Self validating, Timely
- Single concept per test
- Single assert per test
- Three laws of TDD
- First law you may not write production code until you have a failing unit test.
- Second law you may not write more of a unit test than is sufficient to fail.
- You may not write the production code that is sufficient to pass the currently failing test
Classes
- Classes should be small.
- Class size is measured by responsibilities.
- Single Responsibility Principle, classes should have only one reason to change.
- Cohesion should be high, that is, methods and variables of the class are co-dependent