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') \ . ' language-server --protocol=lsp' Execute(The executable should be configurable): let g:ale_dart_analysis_server_executable = 'foobar' AssertLinter 'foobar', ale#Escape('foobar') \ . ' language-server --protocol=lsp' Execute(Should be able to disable new language-server command): let g:ale_dart_analysis_server_enable_language_server = 0 AssertLinter 'dart', ale#Escape('dart') \ . ' ./snapshots/analysis_server.dart.snapshot --lsp'