[expect_tests] Add show_missing flag to coverage.report.

recipe_engine/third_party/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.
 
 from cStringIO import StringIO
 import os
 import socket
 import threading
 
 import coverage
@@ skipping 66 matching lines @@
   def report(self, verbose, threshold, omit=None):
     fail = False
 
     if self.enabled:
       if self.html_report:
         self.cov.html_report(directory=self.html_report, omit=omit)
 
       outf = StringIO()
 
       try:
-        coverage_percent = self.cov.report(file=outf, omit=omit)
+        coverage_percent = self.cov.report(
+          file=outf, omit=omit, 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%'
 
@@ skipping 12 matching lines @@
         print ('FATAL: Test coverage %.f%% is not the required %.f%% threshold'
                % (int(coverage_percent), int(threshold)))
 
     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)