Writing readable tests

Lightning Talk presented at the LSCC Talks #14 event.

Transcript

1. Writing readable tests Separating mechanics from data Alex Tercete @alextercete
2. https://www.flickr.com/photos/vdepizzol/8081618546
3. read- ability?
4. read- ability
5. understand- ability
6. The four elements of readability
7. https://www.flickr.com/photos/tychosnose/15416119182 Context WHERE
8. Reader’s Experience https://www.flickr.com/photos/theilr/5048464567 WHO
9. https://www.flickr.com/photos/thomasclaveirole/463202335 Structure HOW
10. Content https://www.flickr.com/photos/carinefel/13916816466 WHAT
11. Structure Mechanics Content Data
12. https://www.flickr.com/photos/emily3333000/16210254212
13. [Test] public void Add_two_numbers() { var calculator = new RpnCalculator(); calculator.Push(5); calculator.Push(3); Assert.That(calculator.Add(), Is.EqualTo(8)); } [Test] public void Add_two_numbers() { var calculator = new RpnCalculator(); calculator.Push(5); calculator.Push(3); Assert.That(calculator.Add(), Is.EqualTo(8)); }
14. [Test] public void Subtract_two_numbers() { var calculator = new RpnCalculator(); calculator.Push(5); calculator.Push(3); Assert.That(calculator.Subtract(), Is.EqualTo(2)); } [Test] public void Add_two_numbers() { var calculator = new RpnCalculator(); calculator.Push(5); calculator.Push(3); Assert.That(calculator.Add(), Is.EqualTo(8)); } [Test] public void Subtract_two_numbers() { var calculator = new RpnCalculator(); calculator.Push(5); calculator.Push(3); Assert.That(calculator.Subtract(), Is.EqualTo(2)); }
15. Don’t Repeat Yourself
16. [SetUp] public void SetUp() { _calculator = new RpnCalculator(); _calculator.Push(5); _calculator.Push(3); } [Test] public void Add_two_numbers() { Assert.That(_calculator.Add(), Is.EqualTo(8)); } private RpnCalculator _calculator; [SetUp] public void SetUp() { _calculator = new RpnCalculator(); _calculator.Push(5); _calculator.Push(3); } [Test] public void Add_two_numbers() { Assert.That(_calculator.Add(), Is.EqualTo(8)); } [Test] public void Subtract_two_numbers() { Assert.That(_calculator.Subtract(), Is.EqualTo(2)); }
17. Repeat everything
18. [Test] public void Add_two_numbers() { var calculator = new RpnCalculator(); calculator.Push(5); calculator.Push(3); Assert.That(calculator.Add(), Is.EqualTo(8)); } [Test] public void Subtract_two_numbers() { var calculator = new RpnCalculator(); calculator.Push(5); calculator.Push(3); Assert.That(calculator.Subtract(), Is.EqualTo(2)); } [Test] public void Add_two_numbers() { var calculator = new RpnCalculator(); calculator.Push(5); calculator.Push(3); Assert.That(calculator.Add(), Is.EqualTo(8)); }
19. Separate mechanics from data
20. public void SetUp() { _calculator = new RpnCalculator(); } [Test] public void Add_two_numbers() { _calculator.Push(5); _calculator.Push(3); Assert.That(_calculator.Add(), Is.EqualTo(8)); } private RpnCalculator _calculator; [SetUp] public void SetUp() { _calculator = new RpnCalculator(); } [Test] public void Add_two_numbers() { _calculator.Push(5); _calculator.Push(3); Assert.That(_calculator.Add(), Is.EqualTo(8)); } [Test] public void Subtract_two_numbers() { _calculator.Push(5); _calculator.Push(3); Assert.That(_calculator.Subtract(), Is.EqualTo(2)); }
21. If it isn’t data, it must be mechanics https://www.flickr.com/photos/sarahreido/3120877348
22. [Test] public void Show_result_of_an_addition_on_the_display() { var stubCalculatorEngine = Substitute.For<ICalculatorEngine>(); stubCalculatorEngine.Add(1, 2).Returns(3); var mockCalculatorDisplay = Substitute.For<ICalculatorDisplay>(); var calculator = new Calculator(stubCalculatorEngine, mockCalculatorDisplay); calculator.Type('1', '+', '2', '='); mockCalculatorDisplay.Received().Show("3"); }
23. [Test] public void Show_result_of_an_addition_on_the_display() { var stubCalculatorEngine = Substitute.For<ICalculatorEngine>(); stubCalculatorEngine.Add(1, 2).Returns(3); var mockCalculatorDisplay = Substitute.For<ICalculatorDisplay>(); var calculator = new Calculator(stubCalculatorEngine, mockCalculatorDisplay); calculator.Type('1', '+', '2', '='); mockCalculatorDisplay.Received().Show("3"); }
24. [SetUp] public void SetUp() { _stubCalculatorEngine = Substitute.For<ICalculatorEngine>(); _mockCalculatorDisplay = Substitute.For<ICalculatorDisplay>(); _calculator = new Calculator(_stubCalculatorEngine, _mockCalculatorDisplay); } [Test] public void Show_result_of_an_addition_on_the_display() { _stubCalculatorEngine.Add(1, 2).Returns(3); _calculator.Type('1', '+', '2', '='); _mockCalculatorDisplay.Received().Show("3"); }
25. Keep only what is essential to understand the test
26. Thanks! Alex Tercete @alextercete https://speakerdeck.com/alextercete/writing-readable-tests