Globs: Change Glob-not-found warning

The new message suggests users to remove unmatched files from the
respective section of their .coafile. This feedback is more explicit
and  can help to avoid user confusion.

Closes coala#4146

coalib/collecting/Collectors.py

@@ -60,13 +60,14 @@ def icollect(file_paths, ignored_globs=None, match_cache={}):
 
 
 def collect_files(file_paths, log_printer, ignored_file_paths=None,
-                  limit_file_paths=None):
+                  limit_file_paths=None, section_name=''):
     """
     Evaluate globs in file paths and return all matching files
 
     :param file_paths:         File path or list of such that can include globs
     :param ignored_file_paths: List of globs that match to-be-ignored files
     :param limit_file_paths:   List of globs that the files are limited to
+    :param section_name:       Name of currently executing section
     :return:                   List of paths of all matching files
     """
     limit_fnmatch = (functools.partial(fnmatch, globs=limit_file_paths)
@@ -82,7 +83,10 @@ def collect_files(file_paths, log_printer, ignored_file_paths=None,
         collected_files, file_globs_with_files = [], []
 
     _warn_if_unused_glob(log_printer, file_paths, file_globs_with_files,
-                         "No files matching '{}' were found.")
+                         'No files matching \'{}\' were found. '
+                         'If this rule is not required, you can remove it '
+                         'from section [' + section_name + '] in your '
+                         '.coafile to deactivate this warning.')
     limited_files = list(filter(limit_fnmatch, collected_files))
     return limited_files
 
@@ -174,9 +178,9 @@ def collect_bears(bear_dirs, bear_globs, kinds, log_printer,
 
     if warn_if_unused_glob:
         _warn_if_unused_glob(log_printer, bear_globs, bear_globs_with_bears,
-                             "No bears matching '{}' were found. Make sure you "
-                             'have coala-bears installed or you have typed the '
-                             'name correctly.')
+                             'No bears matching \'{}\' were found. Make sure '
+                             'you have coala-bears installed or you have typed '
+                             'the name correctly.')
     return bears_found
 
 

coalib/processes/Processing.py

@@ -356,7 +356,8 @@ def instantiate_processes(section,
         glob_list(section.get('files', '')),
         log_printer,
         ignored_file_paths=glob_list(section.get('ignore', '')),
-        limit_file_paths=glob_list(section.get('limit_files', '')))
+        limit_file_paths=glob_list(section.get('limit_files', '')),
+        section_name=section.name)
 
     # This stores all matched files irrespective of whether coala is run
     # only on changed files or not. Global bears require all the files

tests/collecting/CollectorsTest.py

@@ -27,10 +27,17 @@ def test_file_empty(self):
         self.assertRaises(TypeError, collect_files)
 
     def test_file_invalid(self):
-        self.assertEqual(collect_files(['invalid_path'],
-                                       self.log_printer), [])
+        self.assertEqual(collect_files(file_paths=['invalid_path'],
+                                       log_printer=self.log_printer,
+                                       ignored_file_paths=None,
+                                       limit_file_paths=None,
+                                       section_name='section'), [])
         self.assertEqual([log.message for log in self.log_printer.logs],
-                         ["No files matching 'invalid_path' were found."])
+                         ['No files matching \'invalid_path\' were found. '
+                          'If this rule is not required, you can remove it '
+                          'from section [section] in your .coafile to '
+                          'deactivate this warning.'
+                          ])
 
     def test_file_collection(self):
         self.assertEqual(collect_files([os.path.join(self.collectors_test_dir,
@@ -212,7 +219,7 @@ def test_bear_invalid(self):
                                        ['invalid kind'],
                                        self.log_printer), ([],))
         self.assertEqual([log.message for log in self.log_printer.logs],
-                         ["No bears matching 'invalid_name' were found. Make "
+                         ['No bears matching \'invalid_name\' were found. Make '
                           'sure you have coala-bears installed or you have '
                           'typed the name correctly.'])