stretchr/testify — pull request #39 by xsleonard (2014-02-15 17:28:07+00:00)
Title: ExactError, asserts that err is not nil and its string matches

I had misunderstood assert.Error(), assuming it was doing this already (mistook msgAndArgs as the err.Error() string), until I noticed tests passing that shouldn't have.

ExactError() asserts that an error is non-nil and that err.Error() matches the 2nd argument.