visionmedia/mocha — pull request #949 by bajtos (2013-08-13 08:39:22+00:00)
Title: Preserve custom messages in diff output

When the developer adds extra information to assertion, e.g.

expect('actual', 'description').to.equal('expected'); // Chai style

this extra message ('description') is preserved in the output
even in case when Mocha overwrites the original assertion message with
a string diff.

See also chaijs/chai#189.