Separate expected and actual strings

From email:

> When a test fails due to expect() failing there is both expected and actual results available. One of
> the worst hacks in the IntelliJ code is parsing the error message to extract expected and actual
> string values. We need that to populate the really cool comparison tool IJ has. Would it be difficult
> for the TestErrorEvent to separate those values?

Unfortunately, this is not currently included in the TestFailure exception internally and it would be a fair amount of work to pipe it through. Feel free to file an issue for it, thought, and we can add it in later on.

Start by tracing how TestErrorEvent receives information from the TestFailure exception and where expect() failures are converted into error events. Determine the existing event and exception paths before changing them. Done means expected and actual string values are available separately to consumers such as IntelliJ, without parsing the formatted error message.

Written by the indexing model from the issue text.