MAXIME LEMAITRE – 10/09/2015

xUnit.net… Assert.Awesome(‘‘xUnit.net’’)…

Agenda

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

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/xunit1400 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

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

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

Test Runner Compatibility

Comparing xUnit.net to other frameworksUnit 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] [ExpectedException]

Assert.ThrowsRecord.Exception xUnit.net has done away with the ExpectedException

[SetUp] [TestInitialize] ConstructorWe 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).

Comparing xUnit.net to other frameworksNUnit 2.2 MSTest 2005 xUnit.net 1.x CommentsAreEqualAreNotEqual

AreEqualAreNotEqual

EqualNotEqual

MSTest and xUnit.net support generic versions of this method

AreNotSameAreSame

AreNotSameAreSame

NotSameSame

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 IsEmptyIsNotEmpty n/a Empty

NotEmpty

IsFalseIsTrue

IsFalseIsTrue

FalseTrue

IsInstanceOfTypeIsNotInstanceOfType

IsInstanceOfTypeIsNotInstanceOfType

IsTypeIsNotType

IsNotNullIsNull

IsNotNullIsNull

NotNullNull

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

Concepts

Two different major types of unit testsFacts 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)

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More data sources for theories

PropertyData ClassData

Shared Context between Testshttp://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 Fixturesshared object instances across

multiple test classes

Extensibility

xUnit ExtensibilityHalf 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

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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>)…

Mixing all together …xUnit+Moq+AutoFixture

What is the result of this test ?

Demo

Getting Startedhttp://xunit.github.io/docs/getting-started.html

1. Create a class libraryA 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 runnerConsole or VS

Running Tests

Via Visual Studio Test ExplorerInstall-Package xunit.runner.visualstudio

Via the console test runnerInstall-Package xunit.runner.console

Via any test runner …

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• Nuget ‘All the way’No vsix to install, no templates to install, no setups, … simply nuget as we love it

• Great Community & Active DevelopmentxUnit.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 EcosystemNo 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” TestsThis is the essence of xUnit.net. codify patterns of success (and failure)

Why moving to xUnit ?

Questions

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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