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Writing readable tests
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Alex Tercete
August 20, 2015
Programming
2
190
Writing readable tests
Lightning Talk presented at the LSCC Talks #14 event.
Alex Tercete
August 20, 2015
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Transcript
Writing readable tests Separating mechanics from data Alex Tercete @alextercete
https://www.flickr.com/photos/vdepizzol/8081618546
read- ability?
read- ability
understand- ability
The four elements of readability
https://www.flickr.com/photos/tychosnose/15416119182 Context WHERE
Reader’s Experience https://www.flickr.com/photos/theilr/5048464567 WHO
https://www.flickr.com/photos/thomasclaveirole/463202335 Structure HOW
Content https://www.flickr.com/photos/carinefel/13916816466 WHAT
Structure Mechanics Content Data
https://www.flickr.com/photos/emily3333000/16210254212
[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)); }
[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)); }
Don’t Repeat Yourself
[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)); }
Repeat everything
[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)); }
Separate mechanics from data
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)); }
If it isn’t data, it must be mechanics https://www.flickr.com/photos/sarahreido/3120877348
[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"); }
[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"); }
[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"); }
Keep only what is essential to understand the test
Thanks! Alex Tercete @alextercete https://speakerdeck.com/alextercete/writing-readable-tests