Before: call ale#assert#SetUpLinterTest('haskell', 'stack_build') After: call ale#assert#TearDownLinterTest() Execute(The linter should not be executed when there's no stack.yaml file): AssertLinterNotExecuted Execute(The linter should be executed when there is a stack.yaml file): call ale#test#SetFilename('../test-files/stack/test.hs') AssertLinter 'stack', 'stack build --fast'