Fix bad test

Author: Forgind

test/Microsoft.NET.Sdk.Razor.Tests/MvcBuildIntegrationTestLegacy.cs

@@ -113,9 +113,9 @@ public void Build_ProducesDepsFileWithCompilationContext_ButNoReferences()
             depsFile.Should().Exist();
             var dependencyContext = ReadDependencyContext(depsFile.FullName);
 
-            // Ensure some compile references exist
-            var packageReference = dependencyContext.CompileLibraries.First(l => l.Name == "System.Runtime.CompilerServices.Unsafe");
-            packageReference.Assemblies.Should().NotBeEmpty();
+            // Ensure compile references from a PrivateAssets="all" PackageReference don't exist
+            var packageReference = dependencyContext.CompileLibraries.FirstOrDefault(l => l.Name == "System.Runtime.CompilerServices.Unsafe", defaultValue: null);
+            packageReference.Should().BeNull();
 
             var projectReference = dependencyContext.CompileLibraries.First(l => l.Name == TestProjectName);
             projectReference.Assemblies.Should().NotBeEmpty();