feat(polyfills): add support for embedded Polyfill attributes to prevent type conflicts

Polyfill.targets

@@ -1,4 +1,8 @@
 <Project>
+    <PropertyGroup Condition="'$(EnableTUnitPolyfills)' != 'false'">
+        <PolyUseEmbeddedAttribute>true</PolyUseEmbeddedAttribute>
+    </PropertyGroup>
+
     <ItemGroup Condition="'$(EnableTUnitPolyfills)' != 'false'">
         <PackageReference Include="Polyfill">
             <PrivateAssets>all</PrivateAssets>

Roslyn.props

@@ -1,5 +1,9 @@
 <Project>
 
+    <PropertyGroup>
+        <PolyUseEmbeddedAttribute>true</PolyUseEmbeddedAttribute>
+    </PropertyGroup>
+
     <ItemGroup>
         <PackageReference Include="Microsoft.CodeAnalysis.Common" VersionOverride="$(RoslynVersion).*"/>
         <PackageReference Include="Microsoft.CodeAnalysis.CSharp" VersionOverride="$(RoslynVersion).*"/>

TUnit.Core/TUnit.Core.props

@@ -36,6 +36,8 @@
     <PropertyGroup>
         <!-- Default to enabling polyfills for older frameworks -->
         <EnableTUnitPolyfills Condition="'$(EnableTUnitPolyfills)' == '' and ('$(TargetFramework)' == 'netstandard2.0' or '$(TargetFramework)' == 'netstandard2.1' or '$(TargetFrameworkIdentifier)' == '.NETFramework')">true</EnableTUnitPolyfills>
+        <!-- Use embedded Polyfill attributes to prevent type conflicts across projects -->
+        <PolyUseEmbeddedAttribute Condition="'$(PolyUseEmbeddedAttribute)' == ''">true</PolyUseEmbeddedAttribute>
     </PropertyGroup>
 
     <PropertyGroup>

docs/docs/assertions/collections.md

@@ -290,7 +290,7 @@ public async Task All_Items_Match()
 
 #### With Satisfy
 
-The single parameter overload will match T from IEnumerable<T> - Giving you the relevant assertions for that type.
+The single parameter overload will match T from `IEnumerable<T>` - Giving you the relevant assertions for that type.
 
 ```csharp
 [Test]

docs/docs/getting-started/installation.md

@@ -123,3 +123,8 @@ TUnit is fully compatible with NuGet Central Package Management. When CPM is ena
 If you prefer to manage the Polyfill version yourself, you can:
 - Add `<PackageVersion Include="Polyfill" Version="x.x.x" />` to your `Directory.Packages.props`, OR
 - Disable automatic injection with `<EnableTUnitPolyfills>false</EnableTUnitPolyfills>` and add it manually
+
+### Embedded Polyfill Attributes
+TUnit automatically sets `<PolyUseEmbeddedAttribute>true</PolyUseEmbeddedAttribute>` to ensure that Polyfill types are embedded in each project. This prevents type conflicts when using `InternalsVisibleTo` or when multiple projects in your solution reference Polyfill. Each project gets its own isolated copy of the polyfill types, following the [recommended Polyfill consuming pattern](https://github.com/SimonCropp/Polyfill/blob/main/consuming.md#recommended-consuming-pattern).
+
+You can override this behavior by setting `<PolyUseEmbeddedAttribute>false</PolyUseEmbeddedAttribute>` in your project file if needed.