Notes on TDD - chapter 1

• Related pages
  • Test driven development

Below are notes/tests I made during my reading session of the Test Driven Development: By Example book, by Kent Beck.

The cycle we want to follow in TDD is as follows.

1. Add a little test
2. Run all tests and fail
3. Make a little change
4. Run the tests and succeed
5. Refactor to remove duplication

class Dollar:
    amount: int

    def __init__(self, amount: int):
        self.amount = amount

    def times(self, multipler: int) -> None:
        self.amount *= multipler

If dependency is the problem, duplication is the symptom

Something the author mentions which I never thought about it on reducing duplication, is the fact that self.amount = self.amount * multiplier is code duplication when we compare with self.amount *​​= multiplier.

def test_multiplication():
    d = Dollar(5)
    d.times(2)
    assert d.amount == 10