Before: runtime ale_linters/pyrex/cython.vim After: call ale#linter#Reset() Execute(The cython handler should handle warnings and errors): AssertEqual \ [ \ { \ 'lnum': 42, \ 'col': 7, \ 'text': 'some warning', \ 'type': 'W', \ }, \ { \ 'lnum': 777, \ 'col': 21, \ 'text': 'some error', \ 'type': 'E', \ }, \ ], \ ale_linters#pyrex#cython#Handle(347, [ \ 'warning: file:42:7: some warning', \ 'file:777:21: some error', \ ])