make tests work again

Assets/Mirror/Editor/Weaver/EntryPoint/CompilationFinishedHook.cs

@@ -1,4 +1,3 @@
-#if !UNITY_2020_1_OR_NEWER
 using System;
 using System.Collections.Generic;
 using System.IO;
@@ -28,6 +27,10 @@ public static class CompilationFinishedHook
         // controls weather Weaver errors are reported direct to the Unity console (tests enable this)
         public static bool UnityLogEnabled = true;
 
+// for Unity 2020+ we use ILPostProcessor.
+// only automatically invoke it for older versions.
+// for newer versions, we still call CompilationFinished manually in tests.
+#if !UNITY_2020_1_OR_NEWER
         [InitializeOnLoadMethod]
         public static void OnInitializeOnLoad()
         {
@@ -61,6 +64,7 @@ public static void WeaveExistingAssemblies()
             UnityEditorInternal.InternalEditorUtility.RequestScriptReload();
 #endif
         }
+#endif
 
         static Assembly FindCompilationPipelineAssembly(string assemblyName) =>
             CompilationPipeline.GetAssemblies().First(assembly => assembly.name == assemblyName);
@@ -68,7 +72,7 @@ static Assembly FindCompilationPipelineAssembly(string assemblyName) =>
         static bool CompilerMessagesContainError(CompilerMessage[] messages) =>
             messages.Any(msg => msg.type == CompilerMessageType.Error);
 
-        static void OnCompilationFinished(string assemblyPath, CompilerMessage[] messages)
+        public static void OnCompilationFinished(string assemblyPath, CompilerMessage[] messages)
         {
             // Do nothing if there were compile errors on the target
             if (CompilerMessagesContainError(messages))
@@ -184,4 +188,3 @@ static bool WeaveFromFile(string assemblyPath, string[] dependencies)
         }
     }
 }
-#endif

Assets/Mirror/Editor/Weaver/EntryPoint/CompilationFinishedLogger.cs

@@ -1,6 +1,6 @@
 // logger for compilation finished hook.
 // where we need a callback and Debug.Log.
-#if !UNITY_2020_1_OR_NEWER
+//#if !UNITY_2020_1_OR_NEWER <- still need it for tests in 2020+
 using Mono.CecilX;
 using UnityEngine;
 
@@ -27,4 +27,4 @@ public void Error(string message, MemberReference mr)
         }
     }
 }
-#endif
+//#endif

Assets/Mirror/Tests/Editor/Weaver/WeaverAssembler.cs

@@ -113,6 +113,15 @@ public static void Build()
                         CompilerErrors = true;
                     }
                 }
+
+#if UNITY_2020_1_OR_NEWER
+                // AssemblyBuilder doesn't invoke ILPostProcessor after build.
+                // we need to weave manually here in 2020+.
+                // -> we have the assemblyPath
+                // -> Weaver takes an AssemblyDefinition and resolver
+                // -> simply use the from-file Assembly + Resolver from before.
+                CompilationFinishedHook.OnCompilationFinished(assemblyPath, compilerMessages);
+#endif
             };
 
             // Start build of assembly

Assets/Mirror/Tests/Editor/Weaver/WeaverTests.cs

@@ -45,23 +45,19 @@ protected void BuildAndWeaveTestAssembly(string className, string testName)
         [OneTimeSetUp]
         public void FixtureSetup()
         {
-            // old weaver
-#if !UNITY_2020_1_OR_NEWER
+            // we still use CompilationFinishedHook to run tests in 2020+
             CompilationFinishedHook.UnityLogEnabled = false;
             CompilationFinishedHook.OnWeaverError += HandleWeaverError;
             CompilationFinishedHook.OnWeaverWarning += HandleWeaverWarning;
-#endif
         }
 
         [OneTimeTearDown]
         public void FixtureCleanup()
         {
-            // old weaver
-#if !UNITY_2020_1_OR_NEWER
+            // we still use CompilationFinishedHook to run tests in 2020+
             CompilationFinishedHook.OnWeaverError -= HandleWeaverError;
             CompilationFinishedHook.OnWeaverWarning -= HandleWeaverWarning;
             CompilationFinishedHook.UnityLogEnabled = true;
-#endif
         }
 
         [TearDown]