.NET Framework Contracts for Interfaces


Example

Using Code Contracts it is possible to apply a contract to an interface. This is done by declaring an abstract class that implments the interfaces. The interface should be tagged with the ContractClassAttribute and the contract definition (the abstract class) should be tagged with the ContractClassForAttribute

C# Example...

[ContractClass(typeof(MyInterfaceContract))]
public interface IMyInterface
{
    string DoWork(string input);
}
//Never inherit from this contract defintion class
[ContractClassFor(typeof(IMyInterface))]
internal abstract class MyInterfaceContract : IMyInterface
{
    private MyInterfaceContract() { }

    public string DoWork(string input)
    {
        Contract.Requires(!string.IsNullOrEmpty(input));
        Contract.Ensures(!string.IsNullOrEmpty(Contract.Result<string>()));
        throw new NotSupportedException();
    }
}
public class MyInterfaceImplmentation : IMyInterface
{
    public string DoWork(string input)
    {
        return input;
    }
}

Static Analysis Result...

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