Currently, when you have failed test, the filename+linenumber you get is where the assertion failed. This is suboptimal in situations where you do your assertions in some common test helper, e.g. assertMyCustomFormat(...).
I have created myself a function to work around this problem (see below), but it would be great if Go could do this out of the box. It would make the test failure output a little more wordy, but it is a time saver.