add test to ensure all wrapper methods have the last "int opCode" par…

…ameter

test/Datadog.Trace.ClrProfiler.Managed.Tests/IntegrationSignatureTests.cs

@@ -0,0 +1,37 @@
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+using System.Linq;
+using System.Reflection;
+using Xunit;
+
+namespace Datadog.Trace.ClrProfiler.Managed.Tests
+{
+    public class IntegrationSignatureTests
+    {
+        [SuppressMessage("StyleCop.CSharp.SpacingRules", "SA1009:ClosingParenthesisMustBeSpacedCorrectly", Justification = "Reviewed.")]
+        public static IEnumerable<object[]> GetWrapperMethods()
+        {
+            var integrationsAssembly = typeof(Instrumentation).Assembly;
+
+            // find all methods in Datadog.Trace.ClrProfiler.Managed.dll with [InterceptMethod]
+            var integrations = from wrapperType in integrationsAssembly.GetTypes()
+                               from wrapperMethod in wrapperType.GetRuntimeMethods()
+                               let attributes = wrapperMethod.GetCustomAttributes<InterceptMethodAttribute>(inherit: false)
+                               where attributes.Any()
+                               select new object[] { wrapperMethod };
+
+            return integrations;
+        }
+
+        [Theory]
+        [MemberData(nameof(GetWrapperMethods))]
+        public void WrapperMethodHasOpCodeArgument(MethodInfo wrapperMethod)
+        {
+            // all wrapper methods should have an additional Int32
+            // parameter for the original method call's opcode
+            ParameterInfo lastParameter = wrapperMethod.GetParameters().Last();
+            Assert.Equal(typeof(int), lastParameter.ParameterType);
+            Assert.Equal("opCode", lastParameter.Name);
+        }
+    }
+}