/AutoFixture

Cheat Sheet

Alex Povar edited this page Mar 27, 2018 · 20 revisions

This page contains short code snippets that demonstrate AutoFixture features. All examples assume that a Fixture instance called fixture has previously been created like this:

var fixture = new Fixture();

Completely Autogenerated String

var autoGeneratedText = fixture.Create<string>();

Sample Result

string: "f5cdf6b1-a473-410f-95f3-f427f7abb0c7"

More Information

http://blog.ploeh.dk/2009/04/02/CreatingStringsWithAutoFixture.aspx

Seeded String

Install AutoFixture.SeedExtensions NuGet package to access overloads with a seed.

var generatedTextWithPrefix = fixture.Create("Name");

Sample Result

string: "Name30a35da1-d681-441b-9db3-77ff51728b58"

More Information

http://blog.ploeh.dk/2009/04/02/CreatingStringsWithAutoFixture.aspx

Autogenerated Number

int autoGeneratedNumber = fixture.Create<int>();

Sample Result

int: 27, followed by 9, then by 171, etc.

More Information

https://github.com/AutoFixture/AutoFixture/wiki/Version-History#numbers-are-random

Complex Type

var autoGeneratedClass =
    fixture.Create<ComplexParent>();

Sample Result

ComplexParent:

  • Child: ComplexChild
  • Name: string: "namef70b67ff-05d3-4498-95c9-de74e1aa0c3c"
  • Number: int: 1

More Information

http://blog.ploeh.dk/2009/03/24/HowAutoFixtureCreatesObjects.aspx

Abstract Types

fixture.Register<IMyInterface>(() => 
    new FakeMyInterface());

Sample Result

Every time the fixture instance is asked to create an instance of IMyInterface, it will return a new instance of FakeMyInterface.

More Information

http://blog.ploeh.dk/2009/04/23/DealingWithTypesWithoutPublicConstructors.aspx

Replaced Default Algorithm

fixture.Register<string>(() => "ploeh");
string result = fixture.Create<string>();

Sample Result

string: "ploeh"

More Information

http://blog.ploeh.dk/2009/04/27/ReplacingAutoFixturesDefaultAlgorithms.aspx

Sequence of Strings

var strings = fixture.CreateMany<string>();

Sample Result

IEnumerable:

  • string: "ecc1cc75-cd7a-417f-b477-2913802440b4"
  • string: "fce70a7b-fae5-474f-8055-415ca46eac20"
  • string: "79b45532-d66f-4abc-9311-77ba68dc9e3c"

More Information

http://blog.ploeh.dk/2009/05/11/AnonymousSequencesWithAutoFixture.aspx

Sequence of Custom Objects

var myInstances = fixture.CreateMany<MyClass>();

Sample Result

IEnumerable:

  • MyClass:
  • MyText: string: "MyTextfda10499-e112-476b-924a-2c7b831227f2"
  • MyClass:
  • MyText: string: "MyText6140d5f8-0639-4718-a82b-181d0410f9cf"
  • MyClass:
  • MyText: string: "MyText4a89c288-694a-4a19-a407-7348b70420cf"

More Information

http://blog.ploeh.dk/2009/05/11/AnonymousSequencesWithAutoFixture.aspx

Add to Collection

var list = new List<MyClass>();
fixture.AddManyTo(list);

Sample Result

List:

  • MyClass:
  • MyText: string: "MyTextca86de74-e8df-46b1-bc15-63f763ce9e07"
  • MyClass:
  • MyText: string: "MyTextc45ff7b9-b30e-4246-b535-2eb06bc888c0"
  • MyClass:
  • MyText: string: "MyTextefadfab3-0992-4ecb-a3df-c6f1d5e61f12"

More Information

http://blog.ploeh.dk/2009/05/11/AnonymousSequencesWithAutoFixture.aspx

Set Property

var mc = fixture.Build<MyClass>()
    .With(x => x.MyText, "Ploeh")
    .Create();

Sample Result

MyClass:

  • MyText: string: "Ploeh"

More Information

http://blog.ploeh.dk/2009/06/01/SettingPropertyValuesWhileBuildingAnonymousVariablesWithAutoFixture.aspx

Disable AutoProperties

var sut = fixture.Build<Vehicle>()
    .OmitAutoProperties()
    .Create();

Sample Result

Vehicle:

  • Wheels: int: 4
    The Wheels property will have the default value of 4, instead of having an auto generated value assigned via its setter

More Information

http://blog.ploeh.dk/2009/07/23/DisablingAutoPropertiesInAutoFixture.aspx

Disable Property

var person = fixture.Build<Person>()
    .Without(p => p.Spouse)
    .Create();

Sample Result

Person:

  • BirthDay: DateTime: {18.08.2009 07:37:06}
  • Name: String: "Name949c7c83-c77b-434f-a8fe-e0aa73f81fbe"
  • Spouse: Person: null

More Information

http://blog.ploeh.dk/2009/08/17/OmittingOnlyCertainPropertiesWithAutoFixture.aspx

Perform Action

var mc = fixture.Create<MyClass>();
var mvm = fixture.Build<MyViewModel>()
    .Do(x => x.AvailableItems.Add(mc))
    .With(x => x.SelectedItem, mc)
    .Create();

Sample Result

MyViewModel:

  • AvailableItems: ICollection
  • MyClass (mc)
  • SelectedItem: MyClass (mc)

More Information

http://blog.ploeh.dk/2009/08/25/DoRedux.aspx

Customize Type

var mc = fixture.Create<MyClass>();
fixture.Customize<MyViewModel>(ob => ob
    .Do(x => x.AvailableItems.Add(mc))
    .With(x => x.SelectedItem, mc));
var mvm = fixture.Create<MyViewModel>();

Sample Result

MyViewModel:

  • AvailableItems: ICollection
  • MyClass (mc)
  • SelectedItem: MyClass (mc)

More Information

http://blog.ploeh.dk/2009/09/22/CustomizingATypesBuilderWithAutoFixture.aspx

AutoData Theories

Install AutoFixture.NUnit* or AutoFixture.xUnit* NuGet package.

[Theory, AutoData]
public void Test(int primitiveValue, string text)
{
}

Sample Result

primitiveValue: int: 1
text: string: "textf70b67ff-05d3-4498-95c9-de74e1aa0c3c"

More Information

http://blog.ploeh.dk/2010/10/08/AutoDataTheoriesWithAutoFixture.aspx

Inline AutoData Theories

Install AutoFixture.NUnit* or AutoFixture.xUnit* NuGet package.

[Theory]
[InlineAutoData("foo")]
[InlineAutoData("foo", "bar")]
public void Test(string text1, string text2, MyClass myClass)
{
}

Sample Result

Uses the InlineData values for the the first method arguments, and then uses AutoData for the rest (when the InlineData values run out).

First test run:
text1: string: "foo"
text2: string: "text2c1528179-fd1b-4f5a-a1f3-636e91f8799e"
myClass: an autogenerated variable of type MyClass

Second test run:
text1: string: "foo"
text2: string: "bar"
myClass: an autogenerated variable of type MyClass

More Information

http://www.nikosbaxevanis.com/bonus-bits/2011/08/combining-xunit-data-theories.html

Auto-Mocking with Moq

Install AutoFixture.AutoMoqNuGet package.

fixture.Customize(new AutoMoqCustomization());
var result = fixture.Create<IInterface>();

Sample Result

A mocked instance of a type assignable from IInterface.

Auto-configured Mocks

When new AutoMoqCustomization { ConfigureMembers = true } is added to an IFixture instance, not only will it behave as an Auto-Mocking Container, but it will also automatically configure all the generated Test Doubles (Mocks) so that their members return values generated by AutoFixture.

fixture.Customize(new AutoMoqCustomization { ConfigureMembers = true });
fixture.Inject<int>(1234);

var document = fixture.Create<IDocument>();
Console.WriteLine(document.Id); //1234

This customization will automatically configure any virtual methods/indexers/out parameters and stub all properties. Additionally, class mocks will have their fields set.

More Information

  • Due to a limitation in Moq, auto-configured mode is not able to setup methods with ref parameters.

  • Auto-configured mode does not configure generic methods either. You can, however, easily set these up using the ReturnsUsingFixture extension method:

      converter.Setup(x => x.Convert<double>("10.0"))
           .ReturnsUsingFixture(fixture);

http://blog.ploeh.dk/2010/08/19/AutoFixtureAsAnAutomockingContainer.aspx