Changed behavior when no files require coverage.

build/android/emma_coverage_stats.py

 #!/usr/bin/python
 # Copyright 2015 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.
 
 """Generates incremental code coverage reports for Java code in Chromium.
 
 Usage:
 
   build/android/coverage.py -v --out <output file path> --emma-dir
@@ skipping 432 matching lines @@
       that we should compute coverage information on lines 1 - 3 for file1.
     out_file_path: A string representing the location to write the JSON report.
     coverage_dir: A string representing the file path where the EMMA
       HTML coverage files are located (i.e. folder where index.html is located).
   """
   with open(line_coverage_file) as f:
     potential_files_for_coverage = json.load(f)
   files_for_coverage = {f: lines
                         for f, lines in potential_files_for_coverage.iteritems()
                         if _EmmaCoverageStats.NeedsCoverage(f)}
-  if not files_for_coverage:
+
+  coverage_results = {}
+  if files_for_coverage:
+    code_coverage = _EmmaCoverageStats(coverage_dir, files_for_coverage.keys())
+    coverage_results = code_coverage.GetCoverageDict(
+        files_for_coverage)
+  else:
     logging.info('No Java files requiring coverage were included in %s.',
                  line_coverage_file)
-    return
-
-  code_coverage = _EmmaCoverageStats(coverage_dir, files_for_coverage.keys())
-  coverage_results = code_coverage.GetCoverageDict(
-      files_for_coverage)
 
   with open(out_file_path, 'w+') as out_status_file:
     json.dump(coverage_results, out_status_file)
 
 
 def main():
   argparser = argparse.ArgumentParser()
   argparser.add_argument('--out', required=True, type=str,
                          help='Report output file path.')
   argparser.add_argument('--emma-dir', required=True, type=str,
                          help='EMMA HTML report directory.')
   argparser.add_argument('--lines-for-coverage-file', required=True, type=str,
                          help='File containing a JSON object. Should contain a '
                          'dict mapping file names to lists of line numbers of '
                          'code for which coverage information is desired.')
   argparser.add_argument('-v', '--verbose', action='count',
                          help='Print verbose log information.')
   args = argparser.parse_args()
   run_tests_helper.SetLogLevel(args.verbose)
   GenerateCoverageReport(args.lines_for_coverage_file, args.out, args.emma_dir)
 
 
 if __name__ == '__main__':
   sys.exit(main())