Fix #1178 - Don't use the output from eslint_d for fixing files when the output is an error message

autoload/ale/fixers/eslint.vim

@@ -22,6 +22,17 @@ function! ale#fixers#eslint#ProcessFixDryRunOutput(buffer, output) abort
     return []
 endfunction
 
+function! ale#fixers#eslint#ProcessEslintDOutput(buffer, output) abort
+    " If the output is an error message, don't use it.
+    for l:line in a:output[:10]
+        if l:line =~# '^Error:'
+            return []
+        endif
+    endfor
+
+    return a:output
+endfunction
+
 function! ale#fixers#eslint#ApplyFixForVersion(buffer, version_output) abort
     let l:executable = ale#handlers#eslint#GetExecutable(a:buffer)
     let l:version = ale#semver#GetVersion(l:executable, a:version_output)
@@ -37,6 +48,7 @@ function! ale#fixers#eslint#ApplyFixForVersion(buffer, version_output) abort
         return {
         \   'command': ale#node#Executable(a:buffer, l:executable)
         \       . ' --stdin-filename %s --stdin --fix-to-stdout',
+        \   'process_with': 'ale#fixers#eslint#ProcessEslintDOutput',
         \}
     endif
 

test/fixers/test_eslint_fixer_callback.vader

@@ -101,6 +101,7 @@ Execute(--fix-to-stdout should be used for eslint_d):
   \   'command':
   \     ale#Escape(ale#path#Winify(g:dir . '/../eslint-test-files/app-with-eslint-d/node_modules/.bin/eslint_d'))
   \     . ' --stdin-filename %s --stdin --fix-to-stdout',
+  \   'process_with': 'ale#fixers#eslint#ProcessEslintDOutput',
   \ },
   \ ale#fixers#eslint#ApplyFixForVersion(bufnr(''), ['v3.19.0 (eslint_d v4.2.0)'])
 
@@ -110,6 +111,7 @@ Execute(--fix-to-stdout should be used for eslint_d):
   \   'command':
   \     ale#Escape(ale#path#Winify(g:dir . '/../eslint-test-files/app-with-eslint-d/node_modules/.bin/eslint_d'))
   \     . ' --stdin-filename %s --stdin --fix-to-stdout',
+  \   'process_with': 'ale#fixers#eslint#ProcessEslintDOutput',
   \ },
   \ ale#fixers#eslint#ApplyFixForVersion(bufnr(''), ['4.9.0'])
 
@@ -150,3 +152,21 @@ Execute(The --fix-dry-run post-processor should handle JSON output correctly):
   AssertEqual
   \ ['foo', 'bar'],
   \ ale#fixers#eslint#ProcessFixDryRunOutput(bufnr(''), ['[{"output": "foo\nbar"}]'])
+
+Execute(The eslint_d post-processor should permit regular JavaScript content):
+  AssertEqual
+  \ [
+  \   'const x = ''Error: foo''',
+  \   'const y = 3',
+  \ ],
+  \ ale#fixers#eslint#ProcessEslintDOutput(bufnr(''), [
+  \   'const x = ''Error: foo''',
+  \   'const y = 3',
+  \ ])
+
+Execute(The eslint_d post-processor should handle error messages correctly):
+  AssertEqual
+  \ [],
+  \ ale#fixers#eslint#ProcessEslintDOutput(bufnr(''), [
+  \   'Error: No ESLint configuration found.',
+  \ ])