Clarify TUnit0046 diagnostic message for data source return types (#3843)

* Initial plan

* Update TUnit0046 analyzer message to be clearer

Co-authored-by: thomhurst <30480171+thomhurst@users.noreply.github.com>

* Update documentation for TUnit0046 to match new message

Co-authored-by: thomhurst <30480171+thomhurst@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: thomhurst <30480171+thomhurst@users.noreply.github.com>

Author: Copilot

TUnit.Analyzers/AnalyzerReleases.Shipped.md

@@ -28,7 +28,7 @@ TUnit0038 | Usage | Error | Property with data attribute must have a data source
 TUnit0043 | Usage | Error | Properties with data attributes must use 'required' keyword
 TUnit0044 | Usage | Error | Properties with data attributes must have a setter
 TUnit0045 | Usage | Error | Property has multiple data source attributes - use only one
-TUnit0046 | Usage | Warning | Data source should return Func<T> for lazy evaluation instead of T
+TUnit0046 | Usage | Warning | Data source should return Func<T> for reference types to ensure test isolation
 TUnit0049 | Usage | Error | [Matrix] parameters require [MatrixDataSource] attribute on the test method
 TUnit0050 | Usage | Error | Too many test arguments provided
 TUnit0056 | Usage | Error | Instance data source methods must use [InstanceMethodDataSource] attribute

TUnit.Analyzers/Resources.resx

@@ -328,13 +328,13 @@
         <value>Too many data attributes</value>
     </data>
     <data name="TUnit0046Description" xml:space="preserve">
-        <value>Return a `Func&lt;T&gt;` rather than a `&lt;T&gt;`.</value>
+        <value>When a data source method provides reference types (other than string) as test parameters, it should return Func&lt;T&gt; to defer object creation until the test runs. This prevents shared state between tests and ensures proper test isolation.</value>
     </data>
     <data name="TUnit0046MessageFormat" xml:space="preserve">
-        <value>Return a `Func&lt;T&gt;` rather than a `&lt;T&gt;`.</value>
+        <value>Data source method should return Func&lt;T&gt; for reference type parameters (other than string) to ensure proper test isolation</value>
     </data>
     <data name="TUnit0046Title" xml:space="preserve">
-        <value>Return a `Func&lt;T&gt;` rather than a `&lt;T&gt;`</value>
+        <value>Data source should return Func&lt;T&gt; for reference types</value>
     </data>
     <data name="TUnit0047Description" xml:space="preserve">
         <value>For AsyncLocal values set in before hooks, you must call `context.AddAsyncLocalValues` to access them within tests.</value>