Reland of expect_tests > coverage: no data, no fail (patchset #1 id:1 of https://codereview.chromium

expect_tests/cover.py

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import ConfigParser
 from cStringIO import StringIO
 import os
 import socket
 import sys
 import threading
@@ skipping 92 matching lines @@
       self.cov.combine()
 
   def report(self, verbose):
     fail = False
 
     if self.enabled:
       if self.html_report:
         self.cov.html_report(directory=self.html_report)
 
       outf = StringIO()
-      coverage_percent = self.cov.report(file=outf, show_missing=True)
+
+      try:
+        coverage_percent = self.cov.report(file=outf, show_missing=True)
+      except coverage.CoverageException as ce:
+        if ce.message != 'No data to report.':
+          raise
+        # If we have no data to report, this means that coverage has found no
+        # tests in the module. Earlier version of coverage used to return 100 in
+        # this case, so we simulate it to keep backward compatibility.
+        coverage_percent = 100.0
+        if verbose:
+          print 'No data to report, setting coverage to 100%'
+
       fail = coverage_percent < self.expected_coverage_min
       summary = outf.getvalue().replace('%- 15s' % 'Name', 'Coverage Report', 1)
       if verbose:
         print
         print summary
       elif fail:
         print
         lines = summary.splitlines()
         lines[2:-2] = [l for l in lines[2:-2]
                        if not l.strip().endswith('100%')]
         print '\n'.join(lines)
         print
         print ('FATAL: Test coverage is %.1f%%, target is %d%%.' %
                (coverage_percent, self.expected_coverage_min))
       else:
         print ('Code coverage is %.1f%%, target is %d%%.' %
                (coverage_percent, self.expected_coverage_min))
     return not fail
 
   def create_subprocess_context(self):
     # Can't have this method be the contextmanager because otherwise
     # self (and self.cov) will get pickled to the subprocess, and we don't want
     # that :(
     return _Cover(self.enabled, self.opts)