Exercise: Test the calculator

Let's get our hands dirty. It is now your turn to apply what we learned until now.

The test cases

Here are a few test case names that I would like to to write the test for.

• Add_ShouldReturnZero_WhenAnOppositePositiveAndNegativeNumberAreAdded | Example: -5 + 5 = 0
• Subtract_ShouldSubtractTwoNumbers_WhenTheNumbersAreIntegers | Example: 7 - 5 = 2
• Multiply_ShouldMultiplyTwoNumbers_WhenTheNumbersArePositiveIntegers | Example: 6 * 9 = 54
• Multiply_ShouldReturnZero_WhenOneOfTheNumbersIsZero | Example: 7 * 0 = 0
• Divide_ShouldDivideTwoNumbers_WhenNumbersAreDivisible | Example: 10 / 2 = 5
• Divide_ShouldReturnTheFirstNumber_WhenNumberIsDividedByOne | Example: 7 / 1 = 7

tip

Feel free to call me over to give you a hand 🤚

Solutions

You can expand any individual block to see my solution to each exercise. You are still strongly advised to try and write the methods yourself.

Add_ShouldReturnZero_WhenAnOppositePositiveAndNegativeNumberAreAdded

[Fact]
public void Add_ShouldReturnZero_WhenAnOppositePositiveAndNegativeNumberAreAdded()
{
    // Arrange
    var calculator = new IntCalculator();

    // Act
    var result = calculator.Add(5, -5);
    
    // Assert
    result.Should().Be(0);
}

Subtract_ShouldSubtractTwoNumbers_WhenTheNumbersAreIntegers

[Fact]
public void Subtract_ShouldSubtractTwoNumbers_WhenTheNumbersAreIntegers()
{
    // Arrange
    var calculator = new IntCalculator();

    // Act
    var result = calculator.Subtract(7, 5);

    // Assert
    result.Should().Be(2);
}

Multiply_ShouldMultiplyTwoNumbers_WhenTheNumbersArePositiveIntegers

[Fact]
public void Multiply_ShouldMultiplyTwoNumbers_WhenTheNumbersArePositiveIntegers()
{
    // Arrange
    var calculator = new IntCalculator();

    // Act
    var result = calculator.Multiply(6, 9);
    
    // Assert
    result.Should().Be(54);
}

Multiply_ShouldReturnZero_WhenOneOfTheNumbersIsZero

[Fact]
public void Multiply_ShouldReturnZero_WhenOneOfTheNumbersIsZero()
{
    // Arrange
    var calculator = new IntCalculator();

    // Act
    var result = calculator.Multiply(7, 0);
    
    // Assert
    result.Should().Be(0);
}

Divide_ShouldDivideTwoNumbers_WhenNumbersAreDivisible

[Fact]
public void Divide_ShouldDivideTwoNumbers_WhenNumbersAreDivisible()
{
    // Arrange
    var calculator = new IntCalculator();

    // Act
    var result = calculator.Divide(10, 2);
    
    // Assert
    result.Should().Be(5);
}

Divide_ShouldReturnTheFirstNumber_WhenNumberIsDividedByOne

[Fact]
public void Divide_ShouldReturnTheFirstNumber_WhenNumberIsDividedByOne()
{
    // Arrange
    var calculator = new IntCalculator();

    // Act
    var result = calculator.Divide(7, 1);
    
    // Assert
    result.Should().Be(7);
}