Add a unit test for run_test_cases.py.

tools/isolate/run_test_cases_test.py

+#!/usr/bin/env python
+# Copyright (c) 2012 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 logging
+import os
+import re
+import subprocess
+import sys
+import unittest
+
+ROOT_DIR = os.path.dirname(os.path.abspath(__file__))
+
+sys.path.append(os.path.join(ROOT_DIR, 'data', 'gtest_fake'))
+import gtest_fake
+
+
+class TraceTestCases(unittest.TestCase):
+  def test_simple(self):
+    target = os.path.join(ROOT_DIR, 'data', 'gtest_fake', 'gtest_fake.py')
+    cmd = [
+        sys.executable,
+        os.path.join(ROOT_DIR, 'run_test_cases.py'),
+        '--no-dump',
+        target,
+    ]
+    proc = subprocess.Popen(
+        cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+    # pylint is confused.
+    out, err = proc.communicate() or ('', '')
+    self.assertEquals(0, proc.returncode)
+    expected = (
+      'Note: Google Test filter = Baz.Fail\n'
+      '\n'
+      '%(test_output)s\n'
+      '%(test_footer)s\n'
+      '\n'
+      'Success:    3 75.00%%\n'
+      'Flaky:      0  0.00%%\n'
+      'Fail:       1 25.00%%\n') % {
+        'test_output': gtest_fake.get_test_output('Baz.Fail'),
+        'test_footer': gtest_fake.get_footer(1),
+      }
+
+    self.assertTrue(
+        out.startswith(expected),
+        '\n'.join(['XXX', expected, 'XXX', out[:len(expected)], 'XXX']))
+    remaining_actual = out[len(expected):]
+    regexp = (
+        r'\d+\.\ds Done running 4 tests with 6 executions. \d+\.\d test/s'
+        + '\n')
+    self.assertTrue(re.match(regexp, remaining_actual), remaining_actual)
+    # Progress junk went to stderr.
+    self.assertTrue(err.startswith('\r'), err)
+
+
+if __name__ == '__main__':
+  VERBOSE = '-v' in sys.argv
+  logging.basicConfig(level=logging.DEBUG if VERBOSE else logging.ERROR)
+  unittest.main()