Before:
  call ale#assert#SetUpLinterTest('dart', 'analysis_server')

After:
  call ale#assert#TearDownLinterTest()

Execute(The default command should be correct):
  AssertLinter 'dart', ale#Escape('dart')
  \   . ' ./snapshots/analysis_server.dart.snapshot --lsp'

Execute(The executable should be configurable):
  let g:ale_dart_analysis_server_executable = 'foobar'

  AssertLinter 'foobar', ale#Escape('foobar')
  \   . ' ./snapshots/analysis_server.dart.snapshot --lsp'