How to run tests in this repo

[lance6716]

HI, I want to contribute a feature to errcheck, that is "statement returned error variables must be checked in next statement". This is my commit https://github.com/lance6716/errcheck/commit/43c9b804f2fa62ecd9865c9f440552ecfcd07621

Now I want to add tests to existing test files, but I'm not familiar with the structure of lint repo. Could someone help me to understand how to write a proper test? Thanks.