add a unit test for PossibleIssue_ArgumentCheckOfOptionalParameter

Source/NSubstitute.Acceptance.Specs/FieldReports/PossibleIssue_ArgumentCheckOfOptionalParameter.cs

@@ -0,0 +1,20 @@
+using NUnit.Framework;
+
+namespace NSubstitute.Acceptance.Specs.FieldReports
+{
+    public class PossibleIssue_ArgumentCheckOfOptionalParameter
+    {
+        public interface IInterface
+        {
+            void MethodWithOptionalParameter(object obligatory, object optional = null);
+        }
+
+        [Test]
+        public void PassArgumentCheckForOptionalParameter()
+        {
+            var substitute = Substitute.For<IInterface>();
+            substitute.MethodWithOptionalParameter(new object());
+            substitute.ReceivedWithAnyArgs().MethodWithOptionalParameter(Arg.Any<object>());
+        }
+    }
+}

Source/NSubstitute.Acceptance.Specs/NSubstitute.Acceptance.Specs.csproj

@@ -73,6 +73,7 @@
     <Compile Include="AutoValuesForSubs.cs" />
     <Compile Include="FieldReports\CallingIntoNewSubWithinReturns.cs" />
     <Compile Include="FieldReports\Issue110_CustomExceptions.cs" />
+    <Compile Include="FieldReports\PossibleIssue_ArgumentCheckOfOptionalParameter.cs" />
     <Compile Include="ReturnsAndDoes.cs" />
     <Compile Include="ExceptionsWhenCheckingReceivedCalls.cs" />
     <Compile Include="ExceptionsWhenCheckingSequencesOfCalls.cs" />