Before: Save b:ale_groovy_npmgroovylint_fix_options call ale#assert#SetUpFixerTest('groovy', 'npm-groovy-lint') After: Restore call ale#assert#TearDownFixerTest() Execute(The callback should return the correct default values): AssertFixer { \ 'read_temporary_file': 1, \ 'command': ale#Escape('npm-groovy-lint') . ' --fix %t', \ } Execute(The callback should include custom options): let b:ale_groovy_npmgroovylint_fix_options = '--format' AssertFixer { \ 'read_temporary_file': 1, \ 'command': ale#Escape('npm-groovy-lint') . ' --format %t', \ }