Copy expect_tests from build

expect_tests/cover.py

Index: expect_tests/cover.py
diff --git a/expect_tests/cover.py b/expect_tests/cover.py
new file mode 100644
index 0000000000000000000000000000000000000000..961a847733c31a593eff7a72fd6ad4c679a99b5e
--- /dev/null
+++ b/expect_tests/cover.py
@@ -0,0 +1,85 @@
+# 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 coverage
+
+# This is instead of a contextmanager because it causes old pylints to crash :(
+class _Cover(object):
+  def __init__(self, enabled, maybe_kwargs):
+    self.enabled = enabled
+    self.kwargs = maybe_kwargs or {}
+    self.c = None
+
+  def __call__(self, **kwargs):
+    new_kwargs = self.kwargs
+    if self.enabled:
+      new_kwargs = new_kwargs.copy()
+      new_kwargs.update(kwargs)
+    return _Cover(self.enabled, new_kwargs)
+
+  def __enter__(self):
+    if self.enabled:
+      if self.c is None:
+        self.c = coverage.coverage(**self.kwargs)
+        self.c._warn_no_data = False
+      self.c.start()
+
+  def __exit__(self, *_):
+    if self.enabled:
+      self.c.stop()
+      self.c.save()
+
+
+class CoverageContext(object):
+  def __init__(self, name, cover_branches, html_report, enabled=True):
+    self.opts = None
+    self.cov = None
+    self.enabled = enabled
+
+    self.html_report = html_report
+
+    if enabled:
+      self.opts = {
+        'data_file': '.%s_coverage' % name,
+        'data_suffix': True,
+        'branch': cover_branches,
+      }
+      self.cov = coverage.coverage(**self.opts)
+      self.cov.erase()
+
+  def cleanup(self):
+    if self.enabled:
+      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()
+      fail = self.cov.report(file=outf) != 100.0
+      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 not at 100%.'
+
+    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)