AutoFixture, xUnit.net, and Auto Mocking

July 31, 2012 – autofixture, unit testing

The features discussed in this post are available when using AutoFixture decleratively with the xUnit.net extension. In addition, it is required to have at least one of the extensions for Auto Mocking using AutoMoq, AutoRhinoMocks, or AutoFakeItEasy.

To install AutoFixture with xUnit.net data theories, run the following command in the Package Manager Console:

PM> Install-Package AutoFixture.Xunit

In the test method below we would like to use xUnit.net data theories to provide:

Auto-generated data specimens for d, s, i, a.
Auto-generated data specimens for _, s, i, a, and inline values for d.
Auto-generated data specimens for _, _, i, a, and inline values for d, s.

public void TestMethod(
    double d, string s, IInterface i, AbstractType a)
{
    Assert.True(
        d != 0    &&
        s != null &&
        i != null &&
        a != null
        );
}

That fact that argument i is an interface and argument a is an abstract class prevents us from using [InlineData], [AutoData], or [InlineAutoData] attributes.

AutoFixture allows us to easily define custom DataAttribute derived types:

By deriving from AutoDataAttribute and passing to the base constructor a customization that enables auto mocking with Moq, Rhino Mocks, or FakeItEasy.
By deriving from CompositeDataAttribute and passing to the base constructor an array of DataAttribute derived type instances, e.g. an instance of InlineDataAttribute and an instance of AutoDataAttribute derived type.

Auto Mocking using Moq

To install AutoFixture with Auto Mocking using Moq, run the following command in the Package Manager Console:

PM> Install-Package AutoFixture.AutoMoq

We decorate the test method with AutoMoqData and InlineAutoMoqData attributes:

[Theory]
[AutoMoqData]
[InlineAutoMoqData(2)]
[InlineAutoMoqData(3, "foo")]
public void WithMoq(
    double d, string s, IInterface i, AbstractType a)
{
    Write(d, s, i, a);
}

Output:

AutoMoqData:
  d = 1
  s = s05080d05-b874-4182-bba5-18678ad9b134
  i = Castle.Proxies.IInterfaceProxy
  a = Castle.Proxies.AbstractTypeProxy
  
InlineAutoMoqData:
  d = 2
  s = sce87888d-8cc8-4f69-927c-c4b1347d3147
  i = Castle.Proxies.IInterfaceProxy
  a = Castle.Proxies.AbstractTypeProxy

InlineAutoMoqData:
  d = 3
  s = foo
  i = Castle.Proxies.IInterfaceProxy
  a = Castle.Proxies.AbstractTypeProxy

Source code:

internal class AutoMoqDataAttribute : AutoDataAttribute
{
    internal AutoMoqDataAttribute()
        : base(new Fixture().Customize(new AutoMoqCustomization()))
    {
    }
}

internal class InlineAutoMoqDataAttribute : CompositeDataAttribute
{
    internal InlineAutoMoqDataAttribute(params object[] values)
        : base(new DataAttribute[] { 
            new InlineDataAttribute(values), new AutoMoqDataAttribute() })
    {
    }
}

More information on AutoFixture with Auto Mocking using Moq can be found at AutoFixture as an auto-mocking container blog post.

Auto Mocking using Rhino Mocks

To install AutoFixture with Auto Mocking using Rhino Mocks, run the following command in the Package Manager Console:

PM> Install-Package AutoFixture.AutoRhinoMocks

We decorate the test method with AutoRhinoMockData and InlineAutoRhinoMockData attributes:

[Theory]
[AutoRhinoMockData]
[InlineAutoRhinoMockData(2)]
[InlineAutoRhinoMockData(3, "foo")]
public void WithRhinoMocks(
    double d, string s, IInterface i, AbstractType a)
{
    Write(d, s, i, a);
}

Ouput:

AutoRhinoMockData:
  d = 1
  s = s01172643-5162-474f-bcfa-319ef40a8272
  i = Castle.Proxies.IInterfaceProxy201f58a5559841bfb41895881489658c
  a = Castle.Proxies.AbstractTypeProxy5a86172bbda14cc098b4c675c5b7e555

InlineAutoRhinoMockData:
  d = 2
  s = sd3b9c112-5181-4daa-9b2f-333c7498044a
  i = Castle.Proxies.IInterfaceProxy201f58a5559841bfb41895881489658c
  a = Castle.Proxies.AbstractTypeProxy5a86172bbda14cc098b4c675c5b7e555
  
InlineAutoRhinoMockData:
  d = 3
  s = foo
  i = Castle.Proxies.IInterfaceProxy201f58a5559841bfb41895881489658c
  a = Castle.Proxies.AbstractTypeProxy5a86172bbda14cc098b4c675c5b7e555

Source code:

internal class AutoRhinoMockDataAttribute : AutoDataAttribute
{
    internal AutoRhinoMockDataAttribute()
        : base(new Fixture().Customize(new AutoRhinoMockCustomization()))
    {
    }
}

internal class InlineAutoRhinoMockDataAttribute : CompositeDataAttribute
{
    internal InlineAutoRhinoMockDataAttribute(params object[] values)
        : base(new DataAttribute[] { 
            new InlineDataAttribute(values), new AutoRhinoMockDataAttribute() })
    {
    }
}

More information on AutoFixture with Auto Mocking using Rhino Mocks can be found at Rhino Mocks-based auto-mocking with AutoFixture blog post.

Auto Mocking using FakeItEasy

To install AutoFixture with Auto Mocking using FakeItEasy, run the following command in the Package Manager Console:

PM> Install-Package AutoFixture.AutoFakeItEasy

We decorate the test method with AutoFakeItEasyData or InlineAutoFakeItEasyData attributes:

[Theory]
[AutoFakeItEasyData]
[InlineAutoFakeItEasyData(2)]
[InlineAutoFakeItEasyData(3, "foo")]
public void WithFakeItEasy(
    double d, string s, IInterface i, AbstractType a)
{
    Write(d, s, i, a);
}

Output:

AutoFakeItEasyData:
  d = 1
  s = s2b4c118b-d18b-4782-992a-d4138c65fd2a
  i = Faked IInterface
  a = Faked AbstractType

InlineAutoFakeItEasyData:
  d = 2
  s = se8da7e09-ea4f-4d16-86bd-4229802e5f5d
  i = Faked IInterface
  a = Faked AbstractType

InlineAutoFakeItEasyData:
  d = 3
  s = foo
  i = Faked IInterface
  a = Faked AbstractType

Source code:

internal class AutoFakeItEasyDataAttribute : AutoDataAttribute
{
    internal AutoFakeItEasyDataAttribute()
        : base(new Fixture().Customize(new AutoFakeItEasyCustomization()))
    {
    }
}

internal class InlineAutoFakeItEasyDataAttribute : CompositeDataAttribute
{
    internal InlineAutoFakeItEasyDataAttribute(params object[] values)
        : base(new DataAttribute[] { 
            new InlineDataAttribute(values), new AutoFakeItEasyDataAttribute() })
    {
    }
}

More information on AutoFixture with Auto Mocking using FakeItEasy can be found at Auto-Mocking with FakeItEasy and AutoFixture blog post.

Nikos Baxevanis collects and shares fine-grained parts from methodologies and tools he uses as a programmer.

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