CS0281 InternalsVisibleTo mismatch in Authentication test builds #3561

Description

Release CI builds that run without ESRP signing enabled fail with CS0281 errors when compiling the Authentication.Test project:

nFriend access was granted by 'Microsoft.Graph.Authentication, Version=2.36.1.0, Culture=neutral, PublicKeyToken=null', but the public key of the output assembly ('') does not match that specified by the InternalsVisibleTo attribute in the granting assembly. n

Root Cause

The InternalsVisibleTo attributes in both Authentication and Authentication.Core use #if DEBUG / #else to conditionally require a PublicKey in Release builds. This assumes Release always means signed, but some CI pipelines build in Release without -EnableSigning, causing a mismatch since neither assembly is strong-named.

Affected Files

• src/Authentication/Authentication/Properties/AssemblyInfo.cs
• src/Authentication/Authentication.Core/Properties/AssemblyInfo.cs

Proposed Fix

• Authentication: Remove the conditional entirely — this assembly is never delay-signed at compile time (CSProjHelper.ps1 doesn't modify Authentication.csproj).
• Authentication.Core: Replace #if DEBUG with #if SIGNED_BUILD and define SIGNED_BUILD in the .csproj when SignAssembly=true, so the condition tracks actual signing state.