DoInstead with Delegate with function returning enum values: Returns wrong enum value

[Lars]

I have a problem when trying to use a DoInstead of a method that returns an enum value.

The mocked function is indeed called as expected. However, the return value (an enum) is not returned correctly. Instead it always returns the first value of the enum.

Using Progress Telerik.JustMock 2019.2.620.1 (with license).

Here is a way to reproduce it (Console application, VS2017, Link to Telerik.JustMock dll):

 

namespace TelerikJustMockBug
{
    using System;
    using Telerik.JustMock;

    class Program
    {
        delegate CompletionCode MockedReadWriteDelegate(byte[] buffer, int count, out int retCount);

        static void Main(string[] args)
        {
            new Program().Run();
        }

        private void Run()
        {
            ClassToMock session = Mock.Create<ClassToMock>();

            Mock.Arrange(() => new ClassToMock()).Returns(session);

            Mock.Arrange(() => session.Read(Arg.IsAny<byte[]>(), Arg.AnyInt, out Arg.Ref(Arg.AnyInt).Value)).DoInstead(new MockedReadWriteDelegate(this.MockedRead));

            ClassToMock c = new ClassToMock();
            CompletionCode result = c.Read(new byte[2], 2, out int retCount);

            if (retCount != 5)
            {
                throw new Exception("retCount was not set correctly");
            }

            if (result != CompletionCode.NOT_SUCCESS)
            {
                // this exception is thrown in my case with 'Wrong result: 0'
                throw new Exception($"Wrong result: {result.ToString()}");
            }
        }

        private CompletionCode MockedRead(byte[] buffer, int count, out int retCount)
        {
            retCount = 5;
            return CompletionCode.NOT_SUCCESS;
        }

        public enum CompletionCode
        {
            SUCCESS = 1,
            NOT_SUCCESS = 2
        }

        public class ClassToMock
        {
            public CompletionCode Read(byte[] buffer, int count, out int retCount)
            {
                throw new Exception("Real implementation - should never be called due to mocking");
            }
        }
    }
}

[Lars]

I found the solution myself.

Instead of "DoInstead" a "Returns" is needed.

[Ivo]

Hello Lars,

I would like to confirm that this is the right solution. By design JustMock ignores the return values in DoInstead clauses, so Returns is the right choice in such case.

If you have any other questions, please feel free to write back to us.

Regards,
Ivo
Progress Telerik