make options for credo configurable (#2337)

* Add credo --strict option

If a user sets 'let g:ale_elixir_credo_strict=1' it will run credo with
--strict instead of suggest.  The default (0) is to run as suggest.

* Added credo docs

ale_linters/elixir/credo.vim

@@ -37,11 +37,22 @@ function! ale_linters#elixir#credo#Handle(buffer, lines) abort
     return l:output
 endfunction
 
+function! ale_linters#elixir#credo#GetMode() abort
+    if get(g:, 'ale_elixir_credo_strict', 0)
+        return '--strict'
+    else
+        return 'suggest'
+    endif
+endfunction
+
 function! ale_linters#elixir#credo#GetCommand(buffer) abort
     let l:project_root = ale#handlers#elixir#FindMixProjectRoot(a:buffer)
+    let l:mode = ale_linters#elixir#credo#GetMode()
 
     return ale#path#CdString(l:project_root)
-    \ . ' mix help credo && mix credo suggest --format=flycheck --read-from-stdin %s'
+    \ . 'mix help credo && '
+    \ . 'mix credo ' . ale_linters#elixir#credo#GetMode()
+    \ . ' --format=flycheck --read-from-stdin %s'
 endfunction
 
 call ale#linter#Define('elixir', {

doc/ale-elixir.txt

@@ -72,6 +72,18 @@ g:ale_elixir_elixir_ls_config                   *g:ale_elixir_elixir_ls_config*
     \ }
 <
   Consult the ElixirLS documentation for more information about settings.
+===============================================================================
+credo                                                        *ale-elixir-credo*
+
+Credo (https://github.com/rrrene/credo)
+
+g:ale_elixir_credo_strict                           *g:ale_elixir_credo_strict*
+
+  Type: Integer
+  Default: 0
+
+  Tells credo to run in strict mode or suggest mode.  Set variable to 1 to
+  enable --strict mode.
 
 ===============================================================================
   vim:tw=78:ts=2:sts=2:sw=2:ft=help:norl:

doc/ale.txt

@@ -119,6 +119,7 @@ ALE supports the following key features for linting:
       mix_format..........................|ale-elixir-mix-format|
       dialyxir............................|ale-elixir-dialyxir|
       elixir-ls...........................|ale-elixir-elixir-ls|
+      credo...............................|ale-elixir-credo|
     elm...................................|ale-elm-options|
       elm-format..........................|ale-elm-elm-format|
       elm-make............................|ale-elm-elm-make|
@@ -2256,6 +2257,7 @@ documented in additional help files.
     mix_format............................|ale-elixir-mix-format|
     dialyxir..............................|ale-elixir-dialyxir|
     elixir-ls.............................|ale-elixir-elixir-ls|
+    credo.................................|ale-elixir-credo|
   elm.....................................|ale-elm-options|
     elm-format............................|ale-elm-elm-format|
     elm-make..............................|ale-elm-elm-make|

test/command_callback/test_elixir_credo.vader

@@ -0,0 +1,28 @@
+Before:
+  call ale#assert#SetUpLinterTest('elixir', 'credo')
+  call ale#test#SetFilename('elixir_paths/mix_project/lib/app.ex')
+
+
+After:
+  unlet! g:ale_elixir_credo_strict
+
+  call ale#assert#TearDownLinterTest()
+
+Execute(Builds credo command with --strict mode when set to 1):
+  let g:ale_elixir_credo_strict = 1
+
+  AssertLinter 'mix',
+  \ ale#path#CdString(ale#path#Simplify(g:dir . '/elixir_paths/mix_project'))
+  \ . 'mix help credo && mix credo --strict --format=flycheck --read-from-stdin %s'
+
+Execute(Builds credo command with suggest mode by default):
+  AssertLinter 'mix',
+  \ ale#path#CdString(ale#path#Simplify(g:dir . '/elixir_paths/mix_project'))
+  \ . 'mix help credo && mix credo suggest --format=flycheck --read-from-stdin %s'
+
+Execute(Builds credo command with suggest mode when set to 0):
+  let g:ale_elixir_credo_strict = 0
+
+  AssertLinter 'mix',
+  \ ale#path#CdString(ale#path#Simplify(g:dir . '/elixir_paths/mix_project'))
+  \ . 'mix help credo && mix credo suggest --format=flycheck --read-from-stdin %s'