Do not cache methods with out parameters, fixes #13

Author: pergerch

src/SpatialFocus.MethodCache.Fody/Extensions/MethodDefinitionExtension.cs

@@ -65,13 +65,15 @@ public static bool IsEligibleForWeaving(this MethodDefinition methodDefinition,
 				return false;
 			}
 
+			bool hasOutParameter = methodDefinition.Parameters.Any(x => x.IsOut);
+
 			bool isSpecialName = methodDefinition.IsSpecialName || methodDefinition.IsGetter || methodDefinition.IsSetter ||
 				methodDefinition.IsConstructor;
 
 			bool hasCompilerGeneratedAttribute =
 				methodDefinition.CustomAttributes.Any(attribute => attribute.AttributeType.Resolve().Equals(typeDefinition));
 
-			return !isSpecialName && !hasCompilerGeneratedAttribute;
+			return !hasOutParameter && !isSpecialName && !hasCompilerGeneratedAttribute;
 		}
 
 		public static CustomAttribute TryGetCacheAttribute(this MethodDefinition methodDefinition, References references)

src/SpatialFocus.MethodCache.TestAssembly/BasicTestClass.cs

@@ -22,6 +22,12 @@ public int Add(int a, int b)
 			return a + b;
 		}
 
+		public int AddAndSubtract(int a, int b, out int difference)
+		{
+			difference = a - b;
+			return a + b;
+		}
+
 		[NoCache]
 		public int UncachedAdd(int a, int b)
 		{

src/SpatialFocus.MethodCache.Tests/MemoryCacheBasicTests.cs

@@ -111,5 +111,20 @@ public void BasicTest6DerivedClass()
 			Assert.Equal(1, mockMemoryCache.CountSets);
 			Assert.Equal(1, mockMemoryCache.CountGets);
 		}
+
+		[Fact]
+		public void BasicTest7NotWeavingMethodWithOutParameter()
+		{
+			using MockMemoryCache mockMemoryCache = MockMemoryCache.Default;
+
+			dynamic instance = TestHelpers.CreateInstance<BasicTestClass>(MemoryCacheBasicTests.TestResult.Assembly, mockMemoryCache);
+
+			dynamic result = instance.AddAndSubtract(1, 2, out int difference);
+
+			Assert.Equal(3, result);
+			Assert.Equal(-1, difference);
+			Assert.Equal(0, mockMemoryCache.CountSets);
+			Assert.Equal(0, mockMemoryCache.CountGets);
+		}
 	}
 }