Simplify and Reduce Test Code with AutoFixture

AutoFixture is a library that you can use alongside your testing framework to reduce the amount of boilerplate test code you need to write and thus improve your productivity.

At its core, AutoFixture helps you setup your tests by generating anonymous test data for you. This anonymous test data can be used to fulfil non-important boilerplate test data; this is test data that is required for the test to execute but whose value is unimportant.

Take the follow abbreviated test:

[Fact]
public void ManualCreation()
{
    // arrange

    Customer customer = new Customer()
    {
        CustomerName = "Amrit"
    };

    Order order = new Order(customer)
    {
        Id = 42,
        OrderDate = DateTime.Now,
        Items =
                      {
                          new OrderItem
                          {
                              ProductName = "Rubber ducks",
                              Quantity = 2
                          }
                      }
    };


    // act and assert phases...
}

Suppose the previous test code was only creating an Order (with associated Customer) just to fulfil some dependency and the actual Customer and OrderItems did not matter. In this case we could use AutoFixture to generate them for us.

AutoFixture can be installed via NuGet and once installed allows a Fixture instance to be instantiated. This Fixture object can then be used to generate anonymous test data and greatly simplify the arrange phase, as the following test shows:

[Fact]
public void AutoCreation()
{
    // arrange

    var fixture = new Fixture();

    Order order = fixture.Create<Order>();

    // act and assert phases...
}

If we were to debug this test we’d see the following values:

AutoFixture anonymous test data generation for complex object graphs

Notice in the preceding screenshot that AutoFixture has created the object graph for us, including the Customer and 3 OrderItem instances.

There’s a lot more to AutoFixture than just this simple example, for example you can combine with the AutoFixture.Xunit2 package to further reduce code:

[Theory, AutoData]
public void SubtractWhenZeroTest(int aPositiveNumber, Calculator sut)
{
    // Act
    sut.Subtract(aPositiveNumber);

    // Assert
    Assert.True(sut.Value < 0);
}

If you want to learn more about how AutoFixture can improve your productivity check out the docs or start watching for free  my AutoFixture Pluralsight course with a free trial:

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New Pluralsight Course - Better .NET Unit Tests with AutoFixture

My new Pluralsight testing course was just released: Better .NET Unit Tests with AutoFixture: Get Started.

AutoFixture is an open source library that allows the simplification of automated .NET tests. It allows for the creation of “anonymous” test data. This is data that is required for the test to execute, but where the exact values are unimportant.

AutoFixture is not dependent upon any specific testing framework, so can be used with xUnit.net, NUnit, MSTest, etc. There are some additional extensions for specific testing frameworks such as xUnit.net that allow further reductions in unit test setup code.

For more info check out the GitHub site or the Pluralsight course.

If you like AutoFixture be sure to give open source thanks to Mark Seemann.

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Using AutoFixture To Generate Anonymous Test Data in Web UI Automation With BDDfy and Seleno

I’m currently working on an AutoFixture Pluralsight course and it got me thinking about using it to generate anonymous test data when writing automated UI tests.

The basic premise is that in addition to using AutoFixture to generate unit test data, it can also be used to populate UI elements where the specific data values are unimportant.

If you are unfamiliar with BDDfy and Seleno, they are part of the TestStack project.

BDDfy allows tests to be written and to produce business readable documentation. Seleno allows the automation of web browsers using Selenium and strongly-typed page object models.

Example Scenario

Imagine that we have an (ASP.NET MVC) web site that allows the addition of members of the royal family.

image

If we wanted to test different king/queen names (but didn’t care about the Regnal number) we could start off by defining some strongly typed (Seleno) page object models:

public class HomePage : Page<AddRoyaltyModel>
{
    public CreatedPage CreateRoyalty(AddRoyaltyModel royal)
    {
        Input.Model(royal);

        return Navigate.To<CreatedPage>(By.Id("Create"));
    }
}

public class CreatedPage : Page
{
}

 

(all the examples in this post are fairly quick-and-dirty to demonstrate the AutoFixture involvement)

 

Next we can write some example in BDDfy (using xUnit.net as the test framework):

public class AddRoyaltyTests
{
    private HomePage _home;
    private CreatedPage _confirmationPage;
    public string Name { get; set; }
    public string Number { get; set; }

    [Fact]
    public void ShouldAddRoyaltiesWithDifferentNames()
    {
        this.Given(x => GivenIAmStartingANewRoyalAddition())
            .And("And I have entered <name> as the royalty name")
            .And("And I have entered <number> as the regnal number")
            .When(x => WhenIChooseToAddTheNewRoyal())
            .Then(x => ThenIShouldSeeAConfirmationOfTheNewRoyalHavingBeenAdded())
            .WithExamples(new ExampleTable("name", "number")
                          {
                              {"Richard", "I"},
                              {"Henry", "I"},
                              {"Elizabeth", "I"}
                          })
            .BDDfy();            
    }



    private void GivenIAmStartingANewRoyalAddition()
    {
        _home = Host.Instance.NavigateToInitialPage<HomeController, HomePage>(x => x.Index());
    }        

    private void WhenIChooseToAddTheNewRoyal()
    {
        var royal = new AddRoyaltyModel
        {
            Name = this.Name,
            RegnalRomanNumeral = this.Number
        };

        _confirmationPage = _home.CreateRoyalty(royal);
    }

    private void ThenIShouldSeeAConfirmationOfTheNewRoyalHavingBeenAdded()
    {
        Assert.Equal("Created ok", _confirmationPage.Title);
    }
}

Notice in the preceding code that even though we don’t care about the Regnal number we are still supplying it in the examples. We could just set it manually to a hardcoded value, and in this simple example that might be ok, but if we had a form with many fields then this  will introduce extra work and may make the test less “refactor-safe”.

The following code shows the removal of the Regnal name/number:

public class AddRoyaltyTestsUsingAutoFixture
{
    private HomePage _home;
    private CreatedPage _confirmationPage;
    public string Name { get; set; }

    [Fact]
    public void ShouldAddRoyaltiesWithDifferentNames()
    {
        this.Given(x => GivenIAmStartingANewRoyalAddition())
            .And("And I have entered <name> as the royalty name")
            .When(x => WhenIChooseToAddTheNewRoyal())
            .Then(x => ThenIShouldSeeAConfirmationOfTheNewRoyalHavingBeenAdded())
            .WithExamples(new ExampleTable("name")
                          {
                              "Richard",
                              "Henry",
                              "Elizabeth"
                          })
            .BDDfy();            
    }

    private void GivenIAmStartingANewRoyalAddition()
    {
        _home = Host.Instance.NavigateToInitialPage<HomeController, HomePage>(x => x.Index());
    }        

    private void WhenIChooseToAddTheNewRoyal()
    {
        var fixture = new Fixture();

        // Use AutoFixture to create anonymous data for all properties except
        // name which is set to the BDDfy example value
        var royal = fixture.Build<AddRoyaltyModel>()
            .With(x => x.Name, this.Name)
            .Create();

        _confirmationPage = _home.CreateRoyalty(royal);
    }

    private void ThenIShouldSeeAConfirmationOfTheNewRoyalHavingBeenAdded()
    {
        Assert.Equal("Created ok", _confirmationPage.Title);
    }
}

In this version, AutoFixture’s Build method is being used to automatically generate test data for all the fields, except the royal name which is set to the name(s) specified in the BDDfy examples.

Running this test results in the following automation:

SelenoAutofixture

 

And produces the following HTML BDDfy report:

image

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New Pluralsight Course: The xUnit.net Testing Framework

My latest Pluralsight course on the xUnit.net testing framework has just been released.

Course Description

Learn the latest in unit testing technology for C#, VB.NET (and other .NET languages) created by the original inventor of NUnit.

xUnit.net is a free, extensible, open source framework designed for programmers that aligns more closely with the .NET platform.

 

You can check it out now on Pluralsight.com.

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