xunit.net, created by James Newkirk and Brad Wilson in 2007, is a widely adopted unit testing framework that emphasizes flexibility, extensibility, and a focus on test-driven development (TDD). The framework incorporates key testing concepts such as 'facts' for invariant testing and 'theories' for data-driven tests, and it promotes best practices such as minimizing setup code and improving test isolation. It is actively developed with a significant community presence and is well-integrated into the .NET ecosystem.

1. MAXIME LEMAITRE – 10/09/2015
xUnit.net
… Assert.Awesome(‘‘xUnit.net’’)…

2. Agenda
• Business Card
• Why xUnit.net ?
• Compatibility & Comparisons
• Concepts
• Extensibility
• Demo
• Conclusion
• Question

3. xUnit.net Business Card
• Created in 2007 by 2 ex-Microsofteees
– James Newkirk @jamesnewkirk
– Brad Wilson @bradwilson
• Quick links
– http://xunit.github.io
Official web site
– https://github.com/xunit
850 commits, 800 stars, 35 contributors, 250 forks
– https://twitter.com/xunit
1400 followers
– https://www.nuget.org/packages/xunit
More than 1M downloads (just for the main pkg)
(2007) – “Since the release of NUnit 2.0,
there have been millions of lines of code
written using the various unit testing
frameworks for .NET. About a year ago it
became clear to myself –James- and Brad
that there were some very clear patterns
of success (and failure) with the tools we
were using for writing tests. Rather than
repeating guidance about “do X” or “don’t
do Y”, it seemed like it was the right time to
reconsider the framework itself and see if
we could codify some of those rules.”,
James Newkirk

4. Lessons learned in Unit Testing (2007)
1. Write tests using the 3A pattern (Arrange, Act, Assert)
2. Keep Your Tests Close (to production code)
3. Use Alternatives to ExpectedException (leads to
uncertainty, violates AAA)
4. Use Small Fixtures (smaller & more focused test classes)
5. Don’t use SetUp/TearDown, TestInit/TestCleanup, …
(improve readability & isolation)
6. Don’t use abstract base test classes (improve readability
& isolation)
7. Improve testability with Inversion of Control (Better test
isolation & decoupled class implementation

5. Why Build xUnit.net ?
http://bradwilson.typepad.com/presentations/xunit-v2.pdf
• Flexibility: static and private methods
• Reduce Friction: fewer attributes
• Safety: create a new instance for every test
• Be explicit: no control flow in attributes
• Runners: be everywhere the developer is
• Consistency: Prefer the language & framework
• Extensibility: not an afterthought
• TDD first: built with and for TDD

6. Test Runner Compatibility

7. Comparing xUnit.net to other frameworks
Unit 2.2 MSTest 2005 xUnit.net 2.x Comments
[Test] [TestMethod] [Fact] Marks a test method.
[TestFixture] [TestClass] n/a
xUnit.net does not require an attribute for a test class; it
looks for all test methods in all public lasses in the assembly.
[ExpectedException]
[ExpectedExce
ption]
Assert.Throws
Record.Exception
xUnit.net has done away with the ExpectedException
[SetUp] [TestInitialize] Constructor
We believe that use of [SetUp] is generally bad. However,
you can implement a parameterless constructor as a direct
replacement.
[TearDown] [TestCleanup] IDisposable.Dispose
We believe that use of [TearDown] is generally bad, but you
can implementIDisposable.Dispose as a direct replacement.
[TestFixtureSetUp] [ClassInitialize] IClassFixture<T> To get per-class fixture setup, use IClassFixture<T>
[TestFixtureTearDown] [ClassCleanup] IClassFixture<T> To get per-class fixture teardown, use IClassFixture<T>
n/a n/a ICollectionFixture<T>
To get per-collection fixture setup and teardown,
implement ICollectionFixture<T> on your test collection.
[Ignore] [Ignore] [Fact(Skip="reason")] Set the Skip parameter on the [Fact] attribute.
[Property] [TestProperty] [Trait] Set arbitrary metadata on a test
n/a [DataSource]
[Theory]
[XxxData]
Theory (data-driven test).

8. Comparing xUnit.net to other frameworks
NUnit 2.2 MSTest 2005 xUnit.net 1.x Comments
AreEqual
AreNotEqual
AreEqual
AreNotEqual
Equal
NotEqual
MSTest and xUnit.net support generic versions of
this method
AreNotSame
AreSame
AreNotSame
AreSame
NotSame
Same
n/a n/a DoesNotThrow
Ensures that the code does not throw any
exceptions
Greater / Less n/a n/a
xUnit.net alternative: Assert.True(x > y)
Assert.True(x < y)
Ignore Inconclusive n/a
IsEmpty
IsNotEmpty
n/a
Empty
NotEmpty
IsFalse
IsTrue
IsFalse
IsTrue
False
True
IsInstanceOfType
IsNotInstanceOfType
IsInstanceOfType
IsNotInstanceOfType
IsType
IsNotType
IsNotNull
IsNull
IsNotNull
IsNull
NotNull
Null
n/a n/a NotInRange Ensures that a value is not in a given inclusive range
n/a n/a Throws Ensures that the code throws an exact exception

9. Concepts

10. Two different major types of unit tests
Facts are tests which are always true.
They test invariant conditions.
Theories are tests which are only true for a
particular set of data (Data Driven Tests)

11. More data sources for theories
PropertyData ClassData
11

12. Shared Context between Tests
http://xunit.github.io/docs/shared-context.html
Constructor and Dispose
shared setup/cleanup code
without sharing object instances
Class Fixtures
shared object instance across
tests in a single class
Collection Fixtures
shared object instances across
multiple test classes

13. Extensibility

14. xUnit Extensibility
Half a decade of developer requests
• Assert (Sample: AssertExtensions )
Use 3rd party assertions or create custom
• Before/After (Sample : UseCulture)
Run code before & after each test runs
• Class Fixtures (Sample : ClassFixtureExample)
Run code before & after all tests in test class
• Collection Fixtures (Sample: CollectionFixtureExample )
Run code before & after all tests in test collection
• Theory Data (Sample: ExcelDataExample )
Provide new DataAttribute
• Test Ordering (Sample: TestOrderExamples)
• Traits (Sample: TraitExtensibility)
• FactAttribute (Sample: TheoryAttribute)
What does it mean to be a test?
• Test frameworks
What does it mean to find and run tests?
• Runners

15. And the Test result is GREEN.
The AutoDataAttribute simply uses a Fixture
object to create the objects declared in the
unit tests parameter list (primitives and
complex types like Mock<T>)…
15
Mixing all together …
xUnit+Moq+AutoFixture
What is the result
of this test ?

16. Demo

17. Getting Started
http://xunit.github.io/docs/getting-started.html
1. Create a class library
A test project is just a class library
2. Add a reference to xUnit.net
3. Write your first tests
4. Add a reference to a xUnit.net runner
Console or VS

18. Running Tests
Via Visual Studio Test Explorer
Install-Package
xunit.runner.visualstudio
Via the console test runner
Install-Package xunit.runner.console
Via any test runner …

19. • Nuget ‘All the way’
No vsix to install, no templates to install, no setups, … simply nuget as we love it
• Great Community & Active Development
xUnit.net is free and open source. The code is hosted on github (850 commits, 3R
contibutors, 800 stars, 250 forks) and the official twitter account has 1400
followers. Many extensions are available (Moq, AutoFixture, …)
• Part of the Next ‘Big Thing’
Do you know ASP.NET 5, Xamarin, DNX, …? xUnit will be the first class citizen and
default choice in .NET in the future
• Well Integrated in the .NET Ecosystem
No troubles to use it because it is already supported everywhere : Team
Foundation Server, CruiseControl.net, AppVeyor, TeamCity, Resharper …
• It Helps to Write “Better, Faster, Stronger” Tests
This is the essence of xUnit.net. codify patterns of success (and failure)
19
Why moving to xUnit ?

20. Questions

21. References
• http://xunit.github.io/
• http://jamesnewkirk.typepad.com/LessonsLearnedinProgrammerTesting.pdf
• http://bradwilson.typepad.com/presentations/xunit-v2.pdf
• http://www.codeproject.com/Articles/825248/The-Dynamic-Duo-of-Unit-Testing-xUnit-net-and-Auto
• https://github.com/xunit/samples.xunit
• http://blog.ploeh.dk/2010/10/08/AutoDataTheorieswithAutoFixture/

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