How can I make Code Contracts ignore a specific assembly reference?

Question

I'm making an extension to Visual Studio. Within the code I'm using Code Contracts to make assertions and checks. I set the warning option level to high.

What I would like to do is maintain that warning level while ignoring any checks made on EnvDTE references.

Consider the following code example:

public static string GetAbsoluteOutputFolder(EnvDTE.Project project)
{
    if (project == null) throw new ArgumentNullException("project");

    var path =
        project.ConfigurationManager.ActiveConfiguration.Properties.Item("OutputPath").Value.ToString();
    //...
}

With my current settings, CC would require me to add the following checks before assigning the path variable:

Contract.Assume(project.ConfigurationManager != null);
Contract.Assume(project.ConfigurationManager.ActiveConfiguration != null);
Contract.Assume(project.ConfigurationManager.ActiveConfiguration.Properties != null);

Therefore what I'd like to do here is to tell CC to "trust" EnvDTE and ignore these types and their properties.

I thought the "Be optimistic on external API" CC option served this very purpose; turns out it doesn't.

Is there a way to make it behave the way I want that would not require a lower warning level?

EDIT: I want a solution that would work at project level and that would still allow "regular" checks to be performed.

Answer 1

Can´t provide a detailed solution but this should be solvable by using either the Baseline Feature or System.Diagnostics.CodeAnalysis.SuppressMessage on assembly level:

[assembly: System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Contracts", "Whatever")]

You can use the "Target" Property of the SuppressMessageAttribute to only ignore the Message on specific Types / Methods / Namespaces:

[SuppressMessage("Microsoft.Contracts", 
                 "CC1055", 
                 Scope="Member", 
                 Target="YouNamespace.EnvDTE.Project")]

Note that the Parameters i used are just a good bet, you´ll have to figure out the correct Scope, MessageId and Target yourself :) On a sidenote, i think the Attribute is Conditional("CODE_ANALYSIS").

The official suggested solution to this problem is to create some sort of wrapper, in your case probably a repository that would create or contain your EnvDTE.Project objects. Then you can add the required Contract.Ensures there.

Answer 2

I don't think it's possible to solve the problem but since C# 6.0 there is a workaround which at least eases the pain a bit:

Instead of

Contract.Assume(project.ConfigurationManager != null);
Contract.Assume(project.ConfigurationManager.ActiveConfiguration != null);
Contract.Assume(project.ConfigurationManager.ActiveConfiguration.Properties != null);

you can now write

Contract.Assume(project.ConfigurationManager?.ActiveConfiguration?.Properties != null);

Answer 3

Have you tried something with : [assembly: Contracts.ContractVerification(false)] at the assembly level ?

You should be able to do it dynamically : https://msdn.microsoft.com/en-us/library/bb458043.aspx

Hope this helps,