Before: Save g:ale_ocaml_ocp_indent_executable Save g:ale_ocaml_ocpindent_options " Use an invalid global executable let g:ale_ocaml_ocp_indent_executable = 'xxxinvalid' let g:ale_ocaml_ocp_indent_options = '' call ale#test#SetDirectory('/testplugin/test/fixers') After: Restore call ale#test#RestoreDirectory() Execute(The ocp_indent callback should return the correct default values): call ale#test#SetFilename('../ocaml-test-files/ocp_inden_testfile.re') AssertEqual \ { \ 'command': ale#Escape('xxxinvalid') \ }, \ ale#fixers#ocp_indent#Fix(bufnr('')) Execute(The ocp_indent callback should include custom ocp_indent options): let g:ale_ocaml_ocp_indent_config = "base=4, type=4" call ale#test#SetFilename('../ocaml-test-files/ocp_inden_testfile.re') AssertEqual \ { \ 'command': ale#Escape('xxxinvalid') \ . ' --config=' . ale#Escape(g:ale_ocaml_ocp_indent_config) \ }, \ ale#fixers#ocp_indent#Fix(bufnr(''))