Fix #760 - Report problems with configuration files for rubocop

ale_linters/ruby/rubocop.vim

@@ -14,11 +14,19 @@ function! ale_linters#ruby#rubocop#GetCommand(buffer) abort
 endfunction
 
 function! ale_linters#ruby#rubocop#Handle(buffer, lines) abort
-    if len(a:lines) == 0
+    if empty(a:lines)
         return []
     endif
 
+    try
         let l:errors = json_decode(a:lines[0])
+    catch
+        return [{
+        \   'lnum': 1,
+        \   'text': 'rubocop configuration error (type :ALEDetail for more information)',
+        \   'detail': join(a:lines, "\n"),
+        \}]
+    endtry
 
     let l:output = []
 
@@ -51,4 +59,5 @@ call ale#linter#Define('ruby', {
 \   'executable_callback': 'ale#handlers#rubocop#GetExecutable',
 \   'command_callback': 'ale_linters#ruby#rubocop#GetCommand',
 \   'callback': 'ale_linters#ruby#rubocop#Handle',
+\   'output_stream': 'both',
 \})

test/handler/test_rubocop_handler.vader

@@ -1,6 +1,11 @@
-Execute(The rubocop handler should parse lines correctly):
+Before:
   runtime ale_linters/ruby/rubocop.vim
 
+After:
+  unlet! g:lines
+  call ale#linter#Reset()
+
+Execute(The rubocop handler should parse lines correctly):
   AssertEqual
   \ [
   \   {
@@ -36,5 +41,19 @@ Execute(The rubocop handler should parse lines correctly):
   \     '{"metadata":{"rubocop_version":"0.47.1","ruby_engine":"ruby","ruby_version":"2.1.5","ruby_patchlevel":"273","ruby_platform":"x86_64-linux-gnu"},"files":[{"path":"my_great_file.rb","offenses":[{"severity":"convention","message":"Prefer single-quoted strings...","cop_name":"Style/SomeCop","corrected":false,"location":{"line":83,"column":29,"length":7}},{"severity":"fatal","message":"Some error","cop_name":"Style/SomeOtherCop","corrected":false,"location":{"line":12,"column":2,"length":1}},{"severity":"warning","message":"Regular warning","cop_name":"Style/WarningCop","corrected":false,"location":{"line":10,"column":5,"length":8}},{"severity":"error","message":"Another error","cop_name":"Style/SpaceBeforeBlockBraces","corrected":false,"location":{"line":11,"column":1,"length":1}}]}],"summary":{"offense_count":4,"target_file_count":1,"inspected_file_count":1}}'
   \ ])
 
-After:
-  call ale#linter#Reset()
+Execute(Parse errors should be handled for rubocop):
+  let g:lines = [
+  \ '/my/project/.rubocop.yml: Layout/MultilineOperationIndentation has the wrong namespace - should be Style',
+  \ '/my/project/.rubocop.yml: Layout/AlignHash has the wrong namespace - should be Style',
+  \ '{"metadata":{"rubocop_version":"0.48.1","ruby_engine":"ruby","ruby_version":"2.4.1","ruby_patchlevel":"111","ruby_platform":"x86_64-darwin16"},"files":[]}',
+  \]
+
+  AssertEqual
+  \ [
+  \   {
+  \     'lnum': 1,
+  \     'text': 'rubocop configuration error (type :ALEDetail for more information)',
+  \     'detail': join(g:lines, "\n"),
+  \   },
+  \ ],
+  \ ale_linters#ruby#rubocop#Handle(347, g:lines)