Before:
  call ale#assert#SetUpLinterTest('elixir', 'mix')
  call ale#test#SetFilename('../test-files/elixir/mix_project/lib/app.ex')

After:
  call ale#assert#TearDownLinterTest()

Execute(The default mix command should be correct):
  AssertLinterCwd ale#path#Simplify(g:dir . '/../test-files/elixir/mix_project')
  AssertLinter 'mix', ale#Escape('mix') . ' compile'

Execute(Build mix commands with an umbrella root):
  call ale#test#SetFilename('../test-files/elixir/umbrella_project/apps/mix_project/lib/app.ex')

  AssertLinterCwd ale#path#Simplify(g:dir . '/../test-files/elixir/umbrella_project')
  AssertLinter 'mix', ale#Escape('mix') . ' compile'