Before:
call ale#assert#SetUpLinterTest('python', 'prospector')
After:
call ale#assert#TearDownLinterTest()
Execute(Setting executable to 'pipenv' appends 'run prospector'):
let g:ale_python_prospector_executable = 'path/to/pipenv'
AssertLinter 'path/to/pipenv',
\ ale#Escape('path/to/pipenv') . ' run prospector'
\ . ' --messages-only --absolute-paths --zero-exit --output-format json %s'