jmw-fr/Jmw.AutoFixture

Helpers for AutoFixture

Jmw.AutoFixture

Some tools to simplify Fixtures and Mocks in Unit Tests using AutoFixture.

Why

Creating Fixtures and Mocks is very repetitive and can require many glue to setup tests.

If you like to check Code Coverage like I do, setting up unit tests can be very challenging and require many many code.

To simply this, I create a specific class for testing a class and I use this class to setup everything I need in my tests, including expected results.

How I setup my tests

So my tests look like :

/// <summary>
/// Function nominal test (i.e. normal functioning).
/// </summary>
[Fact]
[Trait(nameof(MyClass.GetResultAsync), nameof(MyClass))]
public async void Constructor_Test_GuardClauses()
{
    // Arrange
    var moq = new MyClassMocks(TestType.Nominal);
    var sut = moq.Fixture.Create<MyClass>();

    // Act
    var r = await sut.GetResultAsync(moq.Param);

    // Assert
    Assert.NotNull(r);
    Assert.Equal(moq.ExpectedResult, r);
    moq.VerifyAll(true);
}

/// <summary>
/// Test if the function correctly thow exceptions.
/// </summary>
/// <param name="testType">Type of test.</param>
/// <param name="expectedException">Type of expected exception.</param>
[Theory]
[Trait(nameof(MyClass.GetResultAsync), nameof(MyClass))]
[InlineData(TestType.ThrowException, typeof(System.InvalidOperationException))]
public async void GetResultAsync_Must_ThrowException(TestType testType, System.Type expectedException)
{
    // Arrange
    var moq = new MyClassMocks(testType);
    var sut = moq.Fixture.Create<MyClass>();

    // Act
    var ex = await Assert.ThrowsAnyAsync<System.Exception>(async () => await sut.GetResultAsync(moq.Param));

    // Assert
    Assert.NotNull(ex);
    Assert.Equal(expectedException, ex.GetType());
}

The first test simply checks the nominal function of GetResultAsync(). Everything I need is created by MyClassMocks.

In the Assert section, I check the result to be non-null, to be equal to my expected fixtured result and I finally ask my MyClassMocks to check that all function injected in MyClass are correctly called.

The second test setup the mock to generate an exception and I check the thrown exception is correct.

Mocks class

From previous examples, MyClassMocksinherit from the abstract class Mocks from my nuget package. This class simplify the setup of fixtures / moqs.

/// <summary>
/// Type of test emulated.
/// </summary>
public enum TestType
{
    /// <summary>
    /// Norminal function.
    /// </summary>
    Nominal,
}

/// <summary>
/// Mocks for <see cref="MyClassUnitTest" />.
/// </summary>
public class MyClassMocks : Mocks<TestType>
{
        /// <summary>
        /// Initializes a new instance of the <see cref="MyClassMocks"/> class.
        /// </summary>
        /// <param name="typeTest">Type of test to emulate.</param>
        public MyClassMocks(TestType typeTest)
            : base(typeTest)
        {
            Param = CreateFixture<string>();
            ExpectedResult = CreateFixture<string>();

            switch (typeTest)
            {
                case TestType.Nominal:
                    {
                        CreateMock<IRepository>(true)
                            .Setup(m => m.GetSomeDataAsync(It.Is<string>(p => p == Param)))
                            .ReturnsAsync(ExpectedResult);

                        break;
                    }

                case TestType.ThrowException:
                    {
                        CreateMock<IRepository>(true)
                            .Setup(m => m.GetSomeDataAsync(It.Is<string>(p => p == Param)))
                            .Throws(new System.InvalidOperationException());

                        break;
                    }

                default:
                    {
                        throw new System.ArgumentException(nameof(typeTest));
                    }
            }
        }
    }
}