Diagnostics.md

Obligatory rules for exceptions that should be serializable

The following rules are oblige, if you write exceptions that are used in an environment that uses serialization.

SE1010 - Missing Serializable Attribute

An exception that should be serializable, have to be marked with the Serializable-Attribute.

Yields an SerializationException during serialization

namespace SomeNamespace {
    public sealed class CustomError : Exception{
        public CustomError(){}
        public CustomError(string message):base(message){}
        public CustomError(string message, Exception inner):base(message,inner){}
        private CustomError(SerializationInfo info, StreamingContext context) : base(info,context){}
    }
}

Fixes the problem

namespace SomeNamespace {
    [Serializable]
    public sealed class CustomErrorException : Exception{
        public CustomErrorException(){}
        public CustomErrorException(string message):base(message){}
        public CustomErrorException(string message, Exception inner):base(message,inner){}
        private CustomErrorException(SerializationInfo info, StreamingContext context) : base(info,context){}
    }
}

SE1050 - Missing serialization constructor

A serializable exception should have a serialization constructor. That's a constructor that:

• accepts a SerializationInfo object as first parameter
• accepts a StreamingContext object as seconds parameter
• is private if exception is sealed
• is protected if exception is not sealed

The constructor can also be public, but it is recommended to make it proteced or private.

Yields an SerializationException during deserialization

namespace SomeNamespace {
    [Serializable]
    public sealed class CustomError : Exception{
        public CustomError(){}
        public CustomError(string message):base(message){}
        public CustomError(string message, Exception inner):base(message,inner){}
    }
}

Fixes the problem

namespace SomeNamespace {
    [Serializable]
    public sealed class CustomErrorException : Exception{
        public CustomErrorException(){}
        public CustomErrorException(string message):base(message){}
        public CustomErrorException(string message, Exception inner):base(message,inner){}
        private CustomErrorException(SerializationInfo info, StreamingContext context) : base(info,context){}
    }
}

Recommended rules for serializable exceptions

Its recommended to obay the following rules, but they are not oblige. Most devellopers expect the rules to be followed, because:

• Principle of Least surprise - each Exceptions offers the same interface and looks the same way.
• Its easier to use them in mocks an fakes (did you ever try to user SQLExceptions in your code? Have fun!).

SE2010 - Missing parameterless constructor

Per convention, each Exception should have a parameterless constructor.

Not recommended

namespace SomeNamespace {
    [Serializable]
    public sealed class CustomErrorException : Exception{
        public CustomErrorException(string message):base(message){}
        public CustomErrorException(string message, Exception inner):base(message,inner){}
        private CustomErrorException(SerializationInfo info, StreamingContext context) : base(info,context){}
    }
}

Recommended

namespace SomeNamespace {
    [Serializable]
    public sealed class CustomErrorException : Exception{
        public CustomErrorException(){}
        public CustomErrorException(string message):base(message){}
        public CustomErrorException(string message, Exception inner):base(message,inner){}
        private CustomErrorException(SerializationInfo info, StreamingContext context) : base(info,context){}
    }
}

SE2020 - Missing constructor with single parameter of type String

Per convention, each Exception should have a constructor that accepts a message.

Not recommended

namespace SomeNamespace {
    [Serializable]
    public sealed class CustomErrorException : Exception{
        public CustomErrorException(){}
        public CustomErrorException(string message, Exception inner):base(message,inner){}
        private CustomErrorException(SerializationInfo info, StreamingContext context) : base(info,context){}
    }
}

Recommended

namespace SomeNamespace {
    [Serializable]
    public sealed class CustomErrorException : Exception{
        public CustomErrorException(){}
        public CustomErrorException(string message):base(message){}
        public CustomErrorException(string message, Exception inner):base(message,inner){}
        private CustomErrorException(SerializationInfo info, StreamingContext context) : base(info,context){}
    }
}

SE2030 - Missing constructor that accepts String and Exception parameter

Per convention, each Exception should have a constructor that accepts a message and an inner exception.

Not recommended

namespace SomeNamespace {
    [Serializable]
    public sealed class CustomErrorException : Exception{
        public CustomErrorException(){}
        public CustomErrorException(string message):base(message){}
        private CustomErrorException(SerializationInfo info, StreamingContext context) : base(info,context){}
    }
}

Recommended

namespace SomeNamespace {
    [Serializable]
    public sealed class CustomErrorException : Exception{
        public CustomErrorException(){}
        public CustomErrorException(string message):base(message){}
        public CustomErrorException(string message, Exception inner):base(message,inner){}
        private CustomErrorException(SerializationInfo info, StreamingContext context) : base(info,context){}
    }
}

SE3010 - Exception classes should end with Exception

Per convention, each Exception should end with Exception.

Not Recommended

namespace SomeNamespace {
    [Serializable]
    public sealed class CustomError : Exception{
        public CustomError(){}
        public CustomError(string message):base(message){}
        public CustomError(string message, Exception inner):base(message,inner){}
        private CustomError(SerializationInfo info, StreamingContext context) : base(info,context){}
    }
}

Recommended

namespace SomeNamespace {
    [Serializable]
    public sealed class CustomErrorException : Exception{
        public CustomErrorException(){}
        public CustomErrorException(string message):base(message){}
        public CustomErrorException(string message, Exception inner):base(message,inner){}
        private CustomErrorException(SerializationInfo info, StreamingContext context) : base(info,context){}
    }
}