Fix #1168 - Make the ruby linter executable configurable

ale_linters/ruby/ruby.vim

@@ -1,10 +1,22 @@
 " Author: Brandon Roehl - https://github.com/BrandonRoehl
 " Description: Ruby MRI for Ruby files
 
+call ale#Set('ruby_ruby_executable', 'ruby')
+
+function! ale_linters#ruby#ruby#GetExecutable(buffer) abort
+    return ale#Var(a:buffer, 'ruby_ruby_executable')
+endfunction
+
+function! ale_linters#ruby#ruby#GetCommand(buffer) abort
+    let l:executable = ale_linters#ruby#ruby#GetExecutable(a:buffer)
+
+    return ale#Escape(l:executable) . ' -w -c -T1 %t'
+endfunction
+
 call ale#linter#Define('ruby', {
 \   'name': 'ruby',
-\   'executable': 'ruby',
+\   'executable_callback': 'ale_linters#ruby#ruby#GetExecutable',
+\   'command_callback': 'ale_linters#ruby#ruby#GetCommand',
 \   'output_stream': 'stderr',
-\   'command': 'ruby -w -c -T1 %t',
 \   'callback': 'ale#handlers#ruby#HandleSyntaxErrors',
 \})

doc/ale-ruby.txt

@@ -58,10 +58,10 @@ g:ale_ruby_reek_show_wiki_link                 *g:ale_ruby_reek_show_wiki_link*
 ===============================================================================
 rubocop                                                      *ale-ruby-rubocop*
 
-g:ale_ruby_rubocop_executable                   g:ale_ruby_rubocop_executable
-                                                b:ale_ruby_rubocop_executable
+g:ale_ruby_rubocop_executable                   *g:ale_ruby_rubocop_executable*
+                                                *b:ale_ruby_rubocop_executable*
   Type: String
-  Default: 'rubocop'
+  Default: `'rubocop'`
 
   Override the invoked rubocop binary. This is useful for running rubocop
   from binstubs or a bundle.
@@ -75,5 +75,16 @@ g:ale_ruby_rubocop_options                         *g:ale_ruby_rubocop_options*
   This variable can be change to modify flags given to rubocop.
 
 
+===============================================================================
+ruby                                                            *ale-ruby-ruby*
+
+g:ale_ruby_ruby_executable                         *g:ale_ruby_ruby_executable*
+                                                   *b:ale_ruby_ruby_executable*
+  Type: String
+  Default: `'ruby'`
+
+  This variable can be changed to use a different executable for ruby.
+
+
 ===============================================================================
   vim:tw=78:ts=2:sts=2:sw=2:ft=help:norl:

doc/ale.txt

@@ -170,6 +170,7 @@ CONTENTS                                                         *ale-contents*
       rails_best_practices................|ale-ruby-rails_best_practices|
       reek................................|ale-ruby-reek|
       rubocop.............................|ale-ruby-rubocop|
+      ruby................................|ale-ruby-ruby|
     rust..................................|ale-rust-options|
       cargo...............................|ale-rust-cargo|
       rls.................................|ale-rust-rls|

test/command_callback/test_ruby_command_callback.vader

@@ -0,0 +1,25 @@
+Before:
+  Save g:ale_ruby_ruby_executable
+
+  unlet! g:ale_ruby_ruby_executable
+
+  runtime ale_linters/ruby/ruby.vim
+
+After:
+  Restore
+
+  call ale#linter#Reset()
+
+Execute(The default command should be correct):
+  AssertEqual 'ruby', ale_linters#ruby#ruby#GetExecutable(bufnr(''))
+  AssertEqual
+  \ ale#Escape('ruby') . ' -w -c -T1 %t',
+  \ ale_linters#ruby#ruby#GetCommand(bufnr(''))
+
+Execute(The executable should be configurable):
+  let g:ale_ruby_ruby_executable = 'foobar'
+
+  AssertEqual 'foobar', ale_linters#ruby#ruby#GetExecutable(bufnr(''))
+  AssertEqual
+  \ ale#Escape('foobar') . ' -w -c -T1 %t',
+  \ ale_linters#ruby#ruby#GetCommand(bufnr(''))