Before: Save g:ale_go_goimports_executable Save g:ale_go_goimports_options " Use an invalid global executable, so we don't match it. let g:ale_go_goimports_executable = 'xxxinvalid' let g:ale_go_goimports_options = '' call ale#test#SetDirectory('/testplugin/test/fixers') After: Restore call ale#test#RestoreDirectory() Execute(The goimports callback should return 0 with bad executable): call ale#test#SetFilename('../go_files/testfile.go') AssertEqual \ 0, \ ale#fixers#goimports#Fix(bufnr(''))