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Unit Testing/xUnit.net/Test Exceptions

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Create a C# Program

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Create the following C# program. Save it as Multiply.cs

public class Multiply
{
    public double MultiplyValues(double x, double y)
    {
        return x * y;
    }

    public string MultiplyValues(string text, int count)
    {
        if (count < 0)
        {
            throw new System.ArgumentException(
                "count must be greater than or equal to zero");
        }

        var result = new System.Text.StringBuilder().Insert(0, text, count).ToString();
        return result;
    }
}

Create a Test Program

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Create the following C# test program. Save it as MultiplyTest.cs

using Xunit;

public class UnitTest
{
    [Fact]
    public void Multiply2x2Test()
    {
        var multiply = new Multiply();
        var result = multiply.MultiplyValues(2, 2);
        Assert.Equal(4, result);
    }

    [Fact]
    public void MultiplyStringx2Test()
    {
        var multiply = new Multiply();
        var result = multiply.MultiplyValues("test", 2);
        Assert.Equal("testtest", result);
    }

    [Fact]
    public void MultiplyStringTrowsExceptionTest()
    {
        var multiply = new Multiply();

        Assert.Throws<System.ArgumentException>(() =>
            multiply.MultiplyValues("test", -1)
        );
    }
}

Test Success

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Test the program by running it in a terminal or command prompt in the same folder as the project above and observe the results.

dotnet test

Test Failure

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Change the multiply source code somehow, such as multiplying the string by a positive number. Test the program by running Jest again and observe the results.