Fix #775 - Run eslint.js via node on Windows for eslint --fix

autoload/ale/fixers/eslint.vim

@@ -28,8 +28,16 @@ function! ale#fixers#eslint#Fix(buffer) abort
         return 0
     endif
 
+    if ale#Has('win32') && l:executable =~? 'eslint\.js$'
+        " For Windows, if we detect an eslint.js script, we need to execute
+        " it with node, or the file can be opened with a text editor.
+        let l:head = 'node ' . ale#Escape(l:executable)
+    else
+        let l:head = ale#Escape(l:executable)
+    endif
+
     return {
-    \   'command': ale#Escape(l:executable)
+    \   'command': l:head
     \       . ' --config ' . ale#Escape(l:config)
     \       . ' --fix %t',
     \   'read_temporary_file': 1,

test/fixers/test_eslint_fixer_callback.vader

@@ -0,0 +1,34 @@
+Before:
+  call ale#test#SetDirectory('/testplugin/test/fixers')
+
+After:
+  let g:ale_has_override = {}
+  call ale#test#RestoreDirectory()
+
+Execute(The path to eslint.js should be run on Unix):
+  call ale#test#SetFilename('../eslint-test-files/react-app/subdir/testfile.js')
+
+  AssertEqual
+  \ {
+  \   'read_temporary_file': 1,
+  \   'command':
+  \     ale#Escape(simplify(g:dir . '/../eslint-test-files/react-app/node_modules/eslint/bin/eslint.js'))
+  \     . ' --config ' . ale#Escape(simplify(g:dir . '/../eslint-test-files/react-app/.eslintrc.js'))
+  \     . ' --fix %t',
+  \ },
+  \ ale#fixers#eslint#Fix(bufnr(''))
+
+Execute(The eslint fixer with eslint.js should be run with node on Windows):
+  call ale#test#SetFilename('../eslint-test-files/react-app/subdir/testfile.js')
+  let g:ale_has_override['win32'] = 1
+
+  " We have to execute the file with node.
+  AssertEqual
+  \ {
+  \   'read_temporary_file': 1,
+  \   'command': 'node '
+  \     . ale#Escape(simplify(g:dir . '/../eslint-test-files/react-app/node_modules/eslint/bin/eslint.js'))
+  \     . ' --config ' . ale#Escape(simplify(g:dir . '/../eslint-test-files/react-app/.eslintrc.js'))
+  \     . ' --fix %t',
+  \ },
+  \ ale#fixers#eslint#Fix(bufnr(''))