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MSTEST0010: ClassInitialize method should have valid layout

Property Value
Rule ID MSTEST0010
Title ClassInitialize method should have valid layout
Category Usage
Fix is breaking or non-breaking Non-breaking
Enabled by default Yes
Default severity Warning
Introduced in version 3.3.0
Is there a code fix Yes

Cause

A method marked with [ClassInitialize] should have valid layout.

Rule description

MSTest calls [ClassInitialize] to prepare resources shared by a test class, rather than the state of one test-class instance:

Requirement Reason
The method is public. Public methods form MSTest's lifecycle discovery contract. [DiscoverInternals] permits an internal declaring class, not an internal lifecycle method.
The method is static. Class initialization belongs to the class's shared lifecycle, not to any one of the instances created for its tests.
The method is ordinary and isn't abstract or generic. MSTest needs a method body it can invoke without special invocation rules or method type arguments.
The method takes exactly one TestContext parameter. MSTest passes the class-initialization context directly because no per-test instance supplies it to this static callback.
The return type is void, Task, or ValueTask, and the method isn't async void. MSTest must wait for asynchronous initialization and observe its failures before it runs tests that depend on the shared resources.
An abstract or generic declaring class specifies InheritanceBehavior.BeforeEachDerivedClass. Such a base class doesn't run as a concrete test class on its own. The inheritance setting associates its initialization with the concrete derived classes that run the tests.
A sealed declaring class doesn't specify InheritanceBehavior.BeforeEachDerivedClass. A sealed class can't have derived classes, so that inheritance setting has no lifecycle to apply to.

The declaring type supplies the test fixture that owns these callbacks:

  • Use a class so MSTest can associate the callbacks with a test-class hierarchy.
  • Use a public class, or an internal class with [assembly: DiscoverInternals], to meet MSTest's type-discovery contract.
  • Use a non-static class for these fixtures. Test methods need a test-class instance, even when a class-level lifecycle callback is static.
  • Mark a sealed class with [TestClass] or a derived attribute. A sealed class can't supply inherited callbacks to another test class, so it must identify itself as the test container.

How to fix violations

Ensure that the method matches the layout described above.

When to suppress warnings

Do not suppress a warning from this rule. If you ignore this rule, flagged instances will be either skipped or result in runtime error.

Suppress a warning

If you just want to suppress a single violation, add preprocessor directives to your source file to disable and then re-enable the rule.

#pragma warning disable MSTEST0010
// The code that's violating the rule is on this line.
#pragma warning restore MSTEST0010

To disable the rule for a file, folder, or project, set its severity to none in the configuration file.

[*.{cs,vb}]
dotnet_diagnostic.MSTEST0010.severity = none

For more information, see How to suppress code analysis warnings.

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