func Diff(b1, b2 []byte) ([]byte, error)
Diff returns the output of running diff on b1 and b2.
func FindTests(t *testing.T, directory, pattern string) ([]string, func())
FindTests finds all files matching the given pattern. It changes the working directory to `directory`, and returns a function to call to change back to the current directory. This allows tests to assert on alias finding between absolute and relative labels.
func Tdiff(t *testing.T, a, b []byte)
Tdiff logs the Diff output to t.Error.