Add more test coverage for System.Reflection.Pointer (dotnet/corefx#2…

…8143)

* Test that null object reference is properly converted to a null pointer value (this requires special handling)
* Test `Delegate.DynamicInvoke`. This one also uses `System.Reflection.Pointer` and on .NET Native is handled by separate code paths.

Commit migrated from dotnet/corefx@b287402

src/libraries/System.Runtime/tests/System/Reflection/PointerTests.cs

@@ -23,6 +23,10 @@ public void Method(byte* ptr, int expected)
         }
     }
 
+    unsafe delegate void MethodDelegate(byte* ptr, int expected);
+
+    unsafe delegate bool* ReturnDelegate(int expected);
+
     public unsafe class PointerTests
     {
         [Fact]
@@ -90,6 +94,16 @@ public void PointerFieldSetValue(int value)
             Assert.Equal(value, unchecked((int)obj.field));
         }
 
+        [Fact]
+        [SkipOnTargetFramework(TargetFrameworkMonikers.UapAot, "Bug that will be fixed along with the rest of UAPAOT issues here")]
+        public void PointerFieldSetNullValue()
+        {
+            var obj = new PointerHolder();
+            FieldInfo field = typeof(PointerHolder).GetField("field");
+            field.SetValue(obj, null);
+            Assert.Equal(0, unchecked((int)obj.field));
+        }
+
         [Theory]
         [MemberData(nameof(Pointers))]
         public void IntPtrFieldSetValue(int value)
@@ -184,6 +198,15 @@ public void PointerMethodParameter(int value)
             method.Invoke(obj, new[] { Pointer.Box(unchecked((void*)value), typeof(byte*)), value });
         }
 
+        [Fact]
+        [SkipOnTargetFramework(TargetFrameworkMonikers.UapAot, "Pointers through Invoke not implemented: https://github.com/dotnet/corert/issues/2113")]
+        public void PointerNullMethodParameter()
+        {
+            var obj = new PointerHolder();
+            MethodInfo method = typeof(PointerHolder).GetMethod("Method");
+            method.Invoke(obj, new object[] { null, 0 });
+        }
+
         [Theory]
         [MemberData(nameof(Pointers))]
         [SkipOnTargetFramework(TargetFrameworkMonikers.UapAot, "Pointers through Invoke not implemented: https://github.com/dotnet/corert/issues/2113")]
@@ -219,5 +242,60 @@ public void PointerMethodReturn(int value)
             void* actualPointer = Pointer.Unbox(actualValue);
             Assert.Equal(value, unchecked((int)actualPointer));
         }
+
+        [Theory]
+        [MemberData(nameof(Pointers))]
+        [SkipOnTargetFramework(TargetFrameworkMonikers.UapAot, "Pointers through Invoke not implemented: https://github.com/dotnet/corert/issues/2113")]
+        public void PointerMethodDelegateParameter(int value)
+        {
+            var obj = new PointerHolder();
+            MethodDelegate d = obj.Method;
+            d.DynamicInvoke(Pointer.Box(unchecked((void*)value), typeof(byte*)), value);
+        }
+
+        [Fact]
+        [SkipOnTargetFramework(TargetFrameworkMonikers.UapAot, "Pointers through Invoke not implemented: https://github.com/dotnet/corert/issues/2113")]
+        public void PointerNullMethodDelegateParameter()
+        {
+            var obj = new PointerHolder();
+            MethodDelegate d = obj.Method;
+            d.DynamicInvoke(null, 0);
+        }
+
+        [Theory]
+        [MemberData(nameof(Pointers))]
+        [SkipOnTargetFramework(TargetFrameworkMonikers.UapAot, "Pointers through Invoke not implemented: https://github.com/dotnet/corert/issues/2113")]
+        public void IntPtrMethodDelegateParameter(int value)
+        {
+            var obj = new PointerHolder();
+            MethodDelegate d = obj.Method;
+            d.DynamicInvoke((IntPtr)value, value);
+        }
+
+        [Theory]
+        [MemberData(nameof(Pointers))]
+        [SkipOnTargetFramework(TargetFrameworkMonikers.UapAot, "Pointers through Invoke not implemented: https://github.com/dotnet/corert/issues/2113")]
+        public void PointerMethodDelegateParameter_InvalidType(int value)
+        {
+            var obj = new PointerHolder();
+            MethodDelegate d = obj.Method;
+            AssertExtensions.Throws<ArgumentException>(null, () =>
+            {
+                d.DynamicInvoke(Pointer.Box(unchecked((void*)value), typeof(long*)), value);
+            });
+        }
+
+        [Theory]
+        [MemberData(nameof(Pointers))]
+        [SkipOnTargetFramework(TargetFrameworkMonikers.UapAot, "Pointers through Invoke not implemented: https://github.com/dotnet/corert/issues/2113")]
+        public void PointerMethodDelegateReturn(int value)
+        {
+            var obj = new PointerHolder();
+            ReturnDelegate d = obj.Return;
+            object actualValue = d.DynamicInvoke(value);
+            Assert.IsType<Pointer>(actualValue);
+            void* actualPointer = Pointer.Unbox(actualValue);
+            Assert.Equal(value, unchecked((int)actualPointer));
+        }
     }
 }