Document MSTEST0050 analyzer rule (#47608)

* Initial plan

* Add documentation for MSTEST0050 analyzer rule

Co-authored-by: Youssef1313 <[email protected]>

* Fix MSTEST0050 default severity and code fix properties

Co-authored-by: Youssef1313 <[email protected]>

* Update MSTEST0050 documentation based on reviewer feedback

- Change attribute names from AssemblyInitialize/AssemblyCleanup to GlobalTestInitialize/GlobalTestCleanup
- Replace general violations list with specific method requirements
- Simplify the "How to fix violations" section
- Update usage-rules.md for consistency

Co-authored-by: Youssef1313 <[email protected]>

* Address reviewer feedback on MSTEST0050 documentation

Co-authored-by: Youssef1313 <[email protected]>

---------

Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: Youssef1313 <[email protected]>

Author: Copilot

docs/core/testing/mstest-analyzers/mstest0050.md

@@ -0,0 +1,43 @@
+---
+title: "MSTEST0050: Global test fixture should be valid"
+description: "Learn about code analysis rule MSTEST0050: Global test fixture should be valid"
+ms.date: 07/29/2025
+f1_keywords:
+- MSTEST0050
+- GlobalTestFixtureShouldBeValidAnalyzer
+helpviewer_keywords:
+- GlobalTestFixtureShouldBeValidAnalyzer
+- MSTEST0050
+author: Evangelink
+ms.author: amauryleve
+---
+# MSTEST0050: Global test fixture should be valid
+
+| Property                            | Value                                                                                    |
+|-------------------------------------|------------------------------------------------------------------------------------------|
+| **Rule ID**                         | MSTEST0050                                                                               |
+| **Title**                           | Global test fixture should be valid                                                     |
+| **Category**                        | Usage                                                                                    |
+| **Fix is breaking or non-breaking** | Non-breaking                                                                             |
+| **Enabled by default**              | Yes                                                                                      |
+| **Default severity**                | Error                                                                                    |
+| **Introduced in version**           | 3.10.0                                                                                   |
+| **Is there a code fix**             | No                                                                                       |
+
+## Cause
+
+A global test fixture method (marked with `GlobalTestInitializeAttribute` or `GlobalTestCleanupAttribute`) doesn't follow the required layout or has invalid configuration.
+
+## Rule description
+
+Global test fixture methods must follow specific requirements to ensure proper test execution. This rule validates that methods marked with `GlobalTestInitializeAttribute` or `GlobalTestCleanupAttribute` adhere to the correct method signature and configuration rules.
+
+The method must be `public`, `static`, non-generic, have a single parameter of type `TestContext`, and return `void` or `Task`. In addition, the containing type must be `public`, `static`, non-generic, and be marked with `TestClassAttribute`.
+
+## How to fix violations
+
+Ensure that global test fixture methods follow the required layout.
+
+## When to suppress warnings
+
+Don't suppress warnings from this rule. Invalid global test fixture methods will not execute at run-time.

docs/core/testing/mstest-analyzers/usage-rules.md

@@ -43,3 +43,4 @@ Identifier | Name | Description
 [MSTEST0046](mstest0046.md) | StringAssertToAssertAnalyzer | A test method uses <xref:Microsoft.VisualStudio.TestTools.UnitTesting.StringAssert> methods instead of equivalent <xref:Microsoft.VisualStudio.TestTools.UnitTesting.Assert> methods.
 [MSTEST0048](mstest0048.md) | TestContextPropertyUsageAnalyzer | A fixture method (methods with <xref:Microsoft.VisualStudio.TestTools.UnitTesting.AssemblyInitializeAttribute>, <xref:Microsoft.VisualStudio.TestTools.UnitTesting.AssemblyCleanupAttribute>, <xref:Microsoft.VisualStudio.TestTools.UnitTesting.ClassInitializeAttribute>, or <xref:Microsoft.VisualStudio.TestTools.UnitTesting.ClassCleanupAttribute>) accesses restricted <xref:Microsoft.VisualStudio.TestTools.UnitTesting.TestContext> properties.
 [MSTEST0049](mstest0049.md) | FlowTestContextCancellationTokenAnalyzer | A method call within a test context doesn't use the <xref:System.Threading.CancellationToken> available from <xref:Microsoft.VisualStudio.TestTools.UnitTesting.TestContext> when the called method has a parameter or overload that accepts a <xref:System.Threading.CancellationToken>.
+[MSTEST0050](mstest0050.md) | GlobalTestFixtureShouldBeValidAnalyzer | A global test fixture method (marked with `GlobalTestInitializeAttribute` or `GlobalTestCleanupAttribute`) doesn't follow the required layout or has invalid configuration.

docs/navigate/devops-testing/toc.yml

@@ -225,6 +225,8 @@ items:
                         href: ../../core/testing/mstest-analyzers/mstest0048.md
                       - name: MSTEST0049
                         href: ../../core/testing/mstest-analyzers/mstest0049.md
+                      - name: MSTEST0050
+                        href: ../../core/testing/mstest-analyzers/mstest0050.md
       - name: Test platforms
         items:
           - name: Microsoft.Testing.Platform