Comparing xUnit.net to other frameworks

Table of Contents

Attributes

Note: This table was written back when xUnit.net 1.0 has shipped, and needs to be updated with information regarding the latest versions of the unit testing frameworks.

NUnit 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 (exported) classes in the assembly.
[ExpectedException] [ExpectedException] Assert.Throws
Record.Exception
xUnit.net has done away with the ExpectedException attribute in favor of Assert.Throws. See Note 1
[SetUp] [TestInitialize] Constructor We believe that use of [SetUp] is generally bad. However, you can implement a parameterless constructor as a direct replacement. See Note 2
[TearDown] [TestCleanup] IDisposable.Dispose We believe that use of [TearDown] is generally bad. However, you can implement IDisposable.Dispose as a direct replacement. See Note 2
[TestFixtureSetUp] [ClassInitialize] IClassFixture<T> To get per-class fixture setup, implement IClassFixture<T> on your test class. See Note 3
[TestFixtureTearDown] [ClassCleanup] IClassFixture<T> To get per-class fixture teardown, implement IClassFixture<T> on your test class. See Note 3
n/a n/a ICollectionFixture<T> To get per-collection fixture setup and teardown, implement ICollectionFixture<T> on your test collection. See Note 3
[Ignore] [Ignore] [Fact(Skip="reason")] Set the Skip parameter on the [Fact] attribute to temporarily skip a test.
[Property] [TestProperty] [Trait] Set arbitrary metadata on a test
n/a [DataSource] [Theory]
[XxxData]
Theory (data-driven test). See Note 4

Attribute Notes

Note 1: Long-term use of [ExpectedException] has uncovered various problems with it. First, it doesn’t specifically say which line of code should throw the exception, which allows subtle and difficult-to-track failures that show up as passing tests. Second, it doesn’t offer the opportunity to fully inspect details of the exception itself, since the handling is outside the normal code flow of the test. Assert.Throws allows you to test a specific set of code for throwing an exception, and returns the exception during success so you can write further asserts against the exception instance itself.

Note 2: The xUnit.net team feels that per-test setup and teardown creates difficult-to-follow and debug testing code, often causing unnecessary code to run before every single test is run. For more information, see http://jamesnewkirk.typepad.com/posts/2007/09/why-you-should-.html.

Note 3: xUnit.net provides a new way to think about per-fixture data with the use of the IClassFixture<T> and ICollectionFixture<T> interfaces. The runner will create a single instance of the fixture data and pass it through to your constructor before running each test. All the tests share the same instance of fixture data. After all the tests have run, the runner will dispose of the fixture data, if it implements IDisposable. For more information, see Shared Context.

Note 4: xUnit.net ships with support for data-driven tests call Theories. Mark your test with the [Theory] attribute (instead of [Fact]), then decorate it with one or more [XxxData] attributes, including [InlineData] and [MemberData]. For more information, see Getting Started.

Assertions

Note: this table was written back when xUnit.net 1.0 has shipped, and needs to be updated with information regarding the latest versions of the unit testing frameworks.

NUnit 2.2 MSTest 2005 xUnit.net 1.x Comments
AreEqual AreEqual Equal MSTest and xUnit.net support generic versions of this method
AreNotEqual AreNotEqual NotEqual MSTest and xUnit.net support generic versions of this method
AreNotSame AreNotSame NotSame  
AreSame AreSame Same  
Contains Contains Contains  
DoAssert n/a n/a  
n/a DoesNotContain DoesNotContain  
n/a n/a DoesNotThrow Ensures that the code does not throw any exceptions
Fail Fail n/a xUnit.net alternative: Assert.True(false, "message")
Greater n/a n/a xUnit.net alternative: Assert.True(x > y)
Ignore Inconclusive n/a  
n/a n/a InRange Ensures that a value is in a given inclusive range (note: NUnit and MSTest have limited support for InRange on their AreEqual methods)
IsAssignableFrom n/a IsAssignableFrom  
IsEmpty n/a Empty  
IsFalse IsFalse False  
IsInstanceOfType IsInstanceOfType IsType  
IsNaN n/a n/a xUnit.net alternative: Assert.True(double.IsNaN(x))
IsNotAssignableFrom n/a n/a xUnit.net alternative: Assert.False(obj is Type)
IsNotEmpty n/a NotEmpty  
IsNotInstanceOfType IsNotInstanceOfType IsNotType  
IsNotNull IsNotNull NotNull  
IsNull IsNull Null  
IsTrue IsTrue True  
Less n/a n/a xUnit.net alternative: Assert.True(x < y)
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
Copyright © 2017 .NET Foundation. Contributions welcomed at https://github.com/xunit/xunit.github.io.