Fix #923 Use package.json as a last resort for eslint --fix

autoload/ale/fixers/eslint.vim

@@ -9,7 +9,6 @@ function! s:FindConfig(buffer) abort
         \   '.eslintrc.yml',
         \   '.eslintrc.json',
         \   '.eslintrc',
-        \   'package.json',
         \]
             let l:config = ale#path#Simplify(l:path . '/' . l:basename)
 
@@ -19,7 +18,7 @@ function! s:FindConfig(buffer) abort
         endfor
     endfor
 
-    return ''
+    return ale#path#FindNearestFile(a:buffer, 'package.json')
 endfunction
 
 function! ale#fixers#eslint#Fix(buffer) abort

test/fixers/test_eslint_fixer_callback.vader

@@ -17,7 +17,7 @@ Execute(The path to eslint.js should be run on Unix):
   \     . ' --fix %t',
   \ },
   \ ale#fixers#eslint#Fix(bufnr(''))
-  \
+
 Execute(The lower priority configuration file in a nested directory should be preferred):
   call ale#test#SetFilename('../eslint-test-files/react-app/subdir-with-config/testfile.js')
 
@@ -30,3 +30,28 @@ Execute(The lower priority configuration file in a nested directory should be pr
   \     . ' --fix %t',
   \ },
   \ ale#fixers#eslint#Fix(bufnr(''))
+
+Execute(package.json should be used as a last resort):
+  call ale#test#SetFilename('../eslint-test-files/react-app/subdir-with-package-json/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(''))
+
+  call ale#test#SetFilename('../eslint-test-files/package.json')
+
+  AssertEqual
+  \ {
+  \   'read_temporary_file': 1,
+  \   'command':
+  \     ale#Escape(simplify(g:dir . '/../eslint-test-files/node_modules/.bin/eslint'))
+  \     . ' --config ' . ale#Escape(simplify(g:dir . '/../eslint-test-files/package.json'))
+  \     . ' --fix %t',
+  \ },
+  \ ale#fixers#eslint#Fix(bufnr(''))