From a957ab18a332d284b086aee622c8a0f05014e697 Mon Sep 17 00:00:00 2001
From: Aleksey Kliger <aleksey@xamarin.com>
Date: Wed, 24 May 2017 11:18:36 -0400
Subject: [PATCH] [tests] Regression test for #56694

When an AssemblyLoad event fires in a domain, a System.Reflection.Assembly
object is created in that domain for the assembly being loaded.  The bug left
this object alive after the domain was unloaded, which lead to a GC crash.
---
 mono/tests/Makefile.am                 |  1 +
 mono/tests/appdomain-unload-asmload.cs | 57 ++++++++++++++++++++++++++
 2 files changed, 58 insertions(+)
 create mode 100644 mono/tests/appdomain-unload-asmload.cs

diff --git a/mono/tests/Makefile.am b/mono/tests/Makefile.am
index 58b826ef15a..f4182ec0e34 100755
--- a/mono/tests/Makefile.am
+++ b/mono/tests/Makefile.am
@@ -463,6 +463,7 @@ TESTS_CS_SRC=		\
 	assemblyresolve_event2.2.cs	\
 	appdomain-unload-callback.cs	\
 	appdomain-unload-doesnot-raise-pending-events.cs	\
+	appdomain-unload-asmload.cs	\
 	unload-appdomain-on-shutdown.cs	\
 	bug-47295.cs	\
 	loader.cs	\
diff --git a/mono/tests/appdomain-unload-asmload.cs b/mono/tests/appdomain-unload-asmload.cs
new file mode 100644
index 00000000000..5f79890ca53
--- /dev/null
+++ b/mono/tests/appdomain-unload-asmload.cs
@@ -0,0 +1,57 @@
+using System;
+using System.Threading.Tasks;
+
+/* This is a regression test that checks that after an AssemblyLoad event fires
+ * in a domain, the domain can be unloaded.  In bug # 56694, a
+ * System.Reflection.Assembly object from the unloaded domain was kept alive
+ * and crashed the GC.  */
+namespace AppDomainUnloadAsmLoad
+{
+	class Program
+	{
+		static void Main(string[] args)
+		{
+			// Need some threads in play
+			new Program().Run().Wait();
+		}
+
+		private async Task Run()
+		{
+			var appDomain = AppDomain.CreateDomain("Test subdomain", null, AppDomain.CurrentDomain.SetupInformation);
+			try
+			{
+				var driver = (AppDomainTestDriver)appDomain.CreateInstanceAndUnwrap(typeof(AppDomainTestDriver).Assembly.FullName,
+												    typeof(AppDomainTestDriver).FullName);
+				driver.Test();
+			}
+			finally
+			{
+				AppDomain.Unload(appDomain);
+			}
+		}
+	}
+
+	class AppDomainTestDriver : MarshalByRefObject
+	{
+		static AppDomainTestDriver()
+		{
+			// Needs a callback so that the runtime fires the
+			// AssembyLoad event for this domain and materializes a System.Reflection.Assembly
+			AppDomain.CurrentDomain.AssemblyLoad += CurrentDomain_AssemblyLoad;
+		}
+
+		private static void CurrentDomain_AssemblyLoad(object sender, AssemblyLoadEventArgs args)
+		{
+		}
+
+		internal void Test()
+		{
+			/* this can be any class from any assembly that hasn't
+			 * already been loaded into the test domain.
+			 * System.Xml.dll is good because all the tests link
+			 * against it, but it's not otherwise used by this
+			 * domain. */
+			var foo = default(System.Xml.XmlException);
+		}
+    }
+}
-- 
2.25.1