Analyzer and Code Fix testing should allow alternate test failure messages

[KathleenDollard]

There is no current way to alter the message produced by the Analyzer and Code Fix on failure.

Analyzer and Code Fix testing from the templates has a fixed message

This presents a problem for me because I use sample code files and do not know which sample code file failed without a debug breakpoint to evaluate real-time values.

I would like CodeFixVerifier to accept a delegate to create the message. This is the easiest way to give the person writing the tests adequate control over the message.

An alternate message string is not sufficient because there are many reasons someone might have extra information to deliver to the person looking at test failures.

[CyrusNajmabadi]

Moving to the sdk team. CodeFixVerifier is not part of roslyn itself.

[sharwell]

Can you give an example here?

I'm concerned that customizing the error message will make it more difficult for a user to ask for help and us be able to make sense of the error that was presented. If possible, I would prefer to update the library to deliver clearer messages to all users.