Add distinction between reported and ignored errors

This allows us to properly exit if no errors were reported (due to,
for example, # noqa).

flake8/checker.py

@@ -163,8 +163,9 @@ class Manager(object):
 
     def _handle_results(self, filename, results):
         style_guide = self.style_guide
+        reported_results_count = 0
         for (error_code, line_number, column, text, physical_line) in results:
-            style_guide.handle_error(
+            reported_results_count += style_guide.handle_error(
                 code=error_code,
                 filename=filename,
                 line_number=line_number,
@@ -172,6 +173,7 @@ class Manager(object):
                 text=text,
                 physical_line=physical_line,
             )
+        return reported_results_count
 
     def _run_checks_from_queue(self):
         LOG.info('Running checks in parallel')
@@ -221,17 +223,24 @@ class Manager(object):
         ]
 
     def report(self):
+        # type: () -> (int, int)
         """Report all of the errors found in the managed file checkers.
 
         This iterates over each of the checkers and reports the errors sorted
         by line number.
+
+        :returns:
+            A tuple of the total results found and the results reported.
+        :rtype:
+            tuple(int, int)
         """
-        results_found = 0
+        results_reported = results_found = 0
         for checker in self.checkers:
             results = sorted(checker.results, key=lambda tup: (tup[2], tup[3]))
-            self._handle_results(checker.filename, results)
+            results_reported += self._handle_results(checker.filename,
+                                                     results)
             results_found += len(results)
-        return results_found
+        return (results_found, results_reported)
 
     def run_parallel(self):
         """Run the checkers in parallel."""

flake8/main/cli.py

@@ -403,7 +403,11 @@ class Application(object):
         number of errors, warnings, and other messages found.
         """
         LOG.info('Reporting errors')
-        self.result_count = self.file_checker_manager.report()
+        results = self.file_checker_manager.report()
+        self.total_result_count, self.result_count = results
+        LOG.info('Found a total of %d results and reported %d',
+                 self.total_result_count,
+                 self.result_count)
 
     def _run(self, argv):
         # type: (Union[NoneType, List[str]]) -> NoneType

flake8/style_guide.py

@@ -233,8 +233,29 @@ class StyleGuide(object):
 
     def handle_error(self, code, filename, line_number, column_number, text,
                      physical_line=None):
-        # type: (str, str, int, int, str) -> NoneType
-        """Handle an error reported by a check."""
+        # type: (str, str, int, int, str) -> int
+        """Handle an error reported by a check.
+
+        :param str code:
+            The error code found, e.g., E123.
+        :param str filename:
+            The file in which the error was found.
+        :param int line_number:
+            The line number (where counting starts at 1) at which the error
+            occurs.
+        :param int column_number:
+            The column number (where counting starts at 1) at which the error
+            occurs.
+        :param str text:
+            The text of the error message.
+        :param str physical_line:
+            The actual physical line causing the error.
+        :returns:
+            1 if the error was reported. 0 if it was ignored. This is to allow
+            for counting of the number of errors found that were not ignored.
+        :rtype:
+            int
+        """
         error = Error(code, filename, line_number, column_number, text,
                       physical_line)
         if error.filename is None or error.filename == '-':
@@ -247,6 +268,8 @@ class StyleGuide(object):
                 is_included_in_diff):
             self.formatter.handle(error)
             self.listener.notify(error.code, error)
+            return 1
+        return 0
 
     def add_diff_ranges(self, diffinfo):
         """Update the StyleGuide to filter out information not in the diff.