Breaking Changes

NUnit 4.0

See the Migration Guide for moving your tests from NUnit 3.x to NUnit 4.0 if you are using any of the following features:

The Classic Asserts have been moved to a separate library and their namespace and their class name were renamed to: NUnit.Framework.Legacy.ClassicAssert.
The standalone assert classes have also been moved to the NUnit.Framework.Legacy namespace. These classes are:
Assert.That overloads with format specification and params have been removed in favor of an overload using FormattableString.
The lowest framework version supported is now version 4.6.2 and .Net 6.0.

See full list of deprecated issues and breaking changes in the framework.

NUnit 3.10

NUnit.Framework.Constraints.NUnitEqualityComparer.Default was deprecated in favor of new NUnitEqualityComparer().

NUnit 3.8

Removed some deprecated attributes:
TestFixtureSetUpAttribute (use OneTimeSetUpAttribute)
TestFixtureTearDownAttribute (use OneTimeTearDownAttribute)
RequiresSTAAttribute (use ApartmentAttribute)
RequiresMTAAttribute (use ApartmentAttribute)
Removed deprecated Is.StringXxxx syntax elements:
Is.StringStarting (use Does.StartWith)
Is.StringEnding (use Does.EndWith)
Is.StringContaining (use Does.Contain)
Is.StringMatching (use Does.Match)

NUnit 3.7

The AssertionHelper class has now been deprecated. Users can use the NUnit.StaticExpect library as a near drop-in replacement.

NUnit 3.4

Breaking changes introduced in NUnit 3.4

The --teamcity console command-line option now requires the TeamCityEventListener extension to be installed. This only affects users who install the extensions individually or copy them to another directory. If you install using the Windows installer or the NUnit.Console NuGet package the TeamCity extension is included.
String arguments in the names of test cases are no longer truncated to 40 characters.
The .NET 2.0 build of the nunit framework uses a private implementation of System.Linq. NUnit installs the NUnit.System.Linq assembly alongside the nunit.framework assembly. If you copy the framework to another location, you must ensure that both are copied. The extra assembly is not used in other builds because System.Linq is already supported in those environments.

NUnit 3.0

A relatively large number of features present in NUnit 2.6, were either removed in NUnit 3.0 or had their behavior modified in a way that will break existing code.

A key change is that the NUnit Test Engine will not recognize a test assembly that does not reference the NUnit framework directly. Normally, test assemblies use NUnit Asserts, attributes and other Types and methods. However, certain third-party frameworks are designed to completely isolate the user from the details of NUnit. They mediate between the test assembly and the NUnit framework in order to run tests. In such a case, NUnit will indicate that the assembly either contains no tests or the proper driver could not be found. To resolve this situation, simply add one NUnit attribute or other reference. An assembly-level ParallelizableAttribute is useful for this purpose.

Other breaking changes are grouped in the following tables.

Attributes

Name	Notes
ExpectedExceptionAttribute	No longer supported. Use `Assert.Throws` or `Assert.That`.
IgnoreAttribute	The reason is now mandatory
RequiredAddinAttribute	No longer supported.
RequiresMTAAttribute	Deprecated. Use `ApartmentAttribute`
RequiresSTAAttribute	Deprecated. Use `ApartmentAttribute`
SuiteAttribute	No longer supported.
System.MTAThreadAttribute	No longer treated as `RequiresMTAAttribute`
System.STAThreadAttribute	No longer treated as `RequiresSTAAttribute`
TearDown and OneTimeTearDown	There is a change to the logic by which teardown methods are called. See Setup and Teardown Changes for details.
TestCaseAttribute	Named parameter `Result=` is no longer supported. Use `ExpectedResult=`. Named parameter `Ignore=` now takes a string, giving the reason for ignoring the test.
TestCaseSourceAttribute	The attribute forms using a string argument to refer to the data source must now use only static fields, properties or methods.
TestFixtureAttribute	Named parameter `Ignore=` now takes a string, giving the reason for ignoring the test.
TestFixtureSetUpAttribute	Deprecated. Use `OneTimeSetUpAttribute`.
TestFixtureTearDownAttribute	Deprecated. Use `OneTimeTearDownAttribute`.
ValueSourceAttribute	The source name of the data source must now use only static fields, properties or methods.

Assertions and Constraints

Feature	Notes
Assert.IsNullOrEmpty	No longer supported. Use `Assert.That(..., Is.Null.Or.Empty)`
Assert.IsNotNullOrEmpty	No longer supported. Use `Assert.That(..., Is.Not.Null.And.Not.Empty)`
Is.InstanceOfType	No longer supported. Use `Is.InstanceOf`
Is.StringStarting	Deprecated. Use `Does.StartWith`
Is.StringContaining	Deprecated. Use `Does.Contain`
Is.StringEnding	Deprecated. Use `Does.EndWith`
Is.StringMatching	Deprecated. Use `Does.Match`
NullOrEmptyStringConstraint	No longer supported. See `Assert.IsNullOrEmpty` above
Text.All	No longer supported. Use `Has.All` or `Is.All`
Text.Contains	No longer supported. Use `Does.Contain` or `Contains.Substring`
Text.DoesNotContain	No longer supported. Use `Does.Not.Contain`
Text.StartsWith	No longer supported. Use `Does.StartWith`
Text.DoesNotStartWith	No longer supported. Use `Does.Not.StartWith`
Text.EndsWith	No longer supported. Use `Does.EndWith`
Text.DoesNotEndWith	No longer supported. Use `Does.Not.EndWith`
Text.Matches	No longer supported. Use `Does.Match`
Text.DoesNotMatch	No longer supported. Use `Does.Not.Match`

Other Framework Features

Feature	Notes
Addins	No longer supported. See Addin Replacement in the Framework.
CurrentDirectory	No longer set to the directory containing the test assembly. Use `TestContext.CurrentContext.TestDirectory` to locate that directory.
NUnitLite	NUnitLite executable tests must now reference nunit.framework in addition to NUnitLite.
SetUpFixture	Now uses `OneTimeSetUpAttribute` and `OneTimeTearDownAttribute` to designate higher-level setup and teardown methods. `SetUpAttribute` and `TearDownAttribute` are no longer allowed.
TestCaseData	The `Throws` Named Property is no longer available. Use `Assert.Throws` or `Assert.That` in your test case.
TestCaseData	The `Categories` Named Property is no longer available. Use `Properties["Category"]` instead.
TestContext	The fields available in the TestContext have changed, although the same information remains available as for NUnit V2.
Async void tests	No longer supported. Use `async Task` as the method signature instead.

Console Features

The console runner is now called nunit3-console. The following breaking changes apply to the options that the new runner supports.

Option	Function	Notes
`--fixture=STR`	Test fixture or namespace to be loaded	No longer supported. Use --test instead.
`--run=STR`	List of tests to run	No longer supported. Replaced by --test.
`--runlist=PATH`	File containing list of tests to run	No longer supported. Replaced by --testlist.
`--include=LIST`	List of categories to include	No longer supported. Use --where instead.
`--exclude=LIST`	List of categories to exclude	No longer supported. Use --where instead.
`--process=PROCESS`	ProcessModel for test assemblies	Default value is now Separate for a single assembly, Multiple for more than one. Multiple assemblies run in parallel by default.
`--domain=DOMAIN`	DomainUsage for test assemblies	Default value is now Separate for a single assembly, Multiple for more than one.
`--apartment=APT`	Apartment in which to run tests	No longer supported. Use ApartmentAttribute.
`--xml=PATH`	Output result xml to path	No longer supported. Use `--result=SPEC` instead.
`--noxml`	Disable xml result output	No longer supported. Use `--noresult` instead.
`--xmlconsole`	Display XML to the console	No longer supported.
`--basepath`	Set ApplicationBase for execution	No longer supported.
`--privatebinpath`	Specify probing path for execution	No longer supported.
`--cleanup`	Remove left-over cache files	No longer supported.
`--noshadow`	Disable shadow copy	No longer supported. The console runner now disables shadow copy by default. use `--shadowcopy` on the command-line to turn it on.
`--nothread`	Disable use of a separate thread for tests	No longer supported.
`--nodots`	Do not display dots as a progress indicator	No longer supported.