IgnoreResultAction: Add Multiline comment support

Adds support for using multiline comment delimiters, if the
language does not have singleline delimiters.
If no delimiters are found, emits a warning.

Closes #coala#3441

coalib/results/result_actions/IgnoreResultAction.py

@@ -5,6 +5,7 @@
 from os.path import exists
 from os.path import isfile
 import shutil
+import logging
 
 from coala_utils.decorators import enforce_signature
 
@@ -36,10 +37,11 @@ def apply(self, result, original_file_dict, file_diff_dict, language: str,
         """
         Add ignore comment
         """
-        comment_delimiter = Language[
-            language].get_default_version().comment_delimiter
-        ignore_comment = (str(comment_delimiter) + ' Ignore ' + result.origin +
-                          '\n')
+
+        ignore_comment = self.get_ignore_comment(result.origin, language)
+
+        if not ignore_comment:
+            return file_diff_dict
 
         source_range = next(filter(lambda sr: exists(sr.file),
                                    result.affected_code))
@@ -65,3 +67,41 @@ def apply(self, result, original_file_dict, file_diff_dict, language: str,
             file.writelines(ignore_diff.modified)
 
         return file_diff_dict
+
+    def get_ignore_comment(self, origin, language):
+        r"""
+        Returns a string of Ignore Comment, depending on the language
+        Supports Single Line Comments
+
+        >>> IgnoreResultAction().get_ignore_comment("Bear", "css")
+        '/* Ignore Bear */\n'
+
+        And Multiline Comments
+
+        >>> IgnoreResultAction().get_ignore_comment("Bear", "c")
+        '// Ignore Bear\n'
+        """
+        try:
+            comment_delimiter = Language[
+                language].get_default_version().comment_delimiter
+            ignore_comment = (str(comment_delimiter) + ' Ignore ' +
+                              origin + '\n')
+        except AttributeError:
+            # singleline comments not supported by language
+            try:
+                multiline_comment_delimiter = Language[
+                    language].get_default_version().multiline_comment_delimiters
+                start_comment, end_comment = next(iter(
+                                        multiline_comment_delimiter.items()))
+                ignore_comment = (str(start_comment) + ' Ignore ' +
+                                  origin + ' ' +
+                                  str(end_comment) + '\n')
+            except AttributeError:
+                # multiline comments also not supported by language
+                logging.warning(
+                    'coala does not support Ignore in "{language}". Consider'
+                    ' opening an issue at https://github.com/coala/coala/issues'
+                    ' so we can add support for this language.'.format(
+                        language=language))
+                ignore_comment = None
+        return ignore_comment

docs/Developers/Newcomers_Guide.rst

@@ -141,6 +141,15 @@ Now you can start working on it.
 
 .. note::
 
+	As stated before, you should never work on an issue without any
+	assignment. Fortunately, cobot is here to help you! So, if you are
+	interested in picking up an issue just write in the gitter chat the 
+	following command::
+
+		cobot assign <issue_link> 
+
+    Take care to write the full link to the issue 
+
     Before starting to write your first commit, check out this
     link: `Writing good commits <http://coala.io/commit>`_.
 

tests/results/result_actions/IgnoreResultActionTest.py

@@ -71,9 +71,23 @@ def test_ignore(self):
 
             # Apply a second patch, old patch has to stay!
             uut.apply(Result.from_values('else', 'msg', f_a, 1),
-                      file_dict, file_diff_dict, 'c')
+                      file_dict, file_diff_dict, 'css')
             self.assertEqual(
                 file_diff_dict[f_a].modified,
-                ['1  // Ignore else\n', '2  // Ignore origin\n', '3\n'])
+                ['1  /* Ignore else */\n', '2  // Ignore origin\n', '3\n'])
             with open(f_a, 'r') as f:
                 self.assertEqual(file_diff_dict[f_a].modified, f.readlines())
+
+            import logging
+            logger = logging.getLogger()
+
+            with unittest.mock.patch('subprocess.call'):
+                with self.assertLogs(logger, 'WARNING') as log:
+                    uut.apply(Result.from_values('else', 'msg', f_a, 1),
+                              file_dict, file_diff_dict, 'dothraki')
+
+                    self.assertEqual(1, len(log.output))
+                    self.assertIn(
+                        'coala does not support Ignore in "dothraki".',
+                        log.output[0]
+                    )