[Telemetry] Add test to prevents adding new dependencies to telemetry.

tools/telemetry/telemetry/telemetry_dependencies_unittest.py

Index: tools/telemetry/telemetry/telemetry_dependencies_unittest.py
diff --git a/tools/telemetry/telemetry/telemetry_dependencies_unittest.py b/tools/telemetry/telemetry/telemetry_dependencies_unittest.py
new file mode 100644
index 0000000000000000000000000000000000000000..45603b9ff30ea937c8cb1cda8f11f16b6d7afa6d
--- /dev/null
+++ b/tools/telemetry/telemetry/telemetry_dependencies_unittest.py
@@ -0,0 +1,57 @@
+# 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.
+
+import json
+import os
+import unittest
+
+from telemetry.util import path
+from telemetry.util import find_dependencies
+
+
+_TELEMETRY_DEPS_PATH = os.path.join(
+    path.GetTelemetryDir(), 'telemetry', 'TELEMETRY_DEPS')
+
+
+def _GetCurrentTelemetryDependencies():
+  parser = find_dependencies.FindDependenciesCommand.CreateParser()
+  find_dependencies.FindDependenciesCommand.AddCommandLineArgs(parser, None)
+  options, args = parser.parse_args([''])
+  options.positional_args = args
+  return find_dependencies.FindDependencies([], options=options)
+
+
+def _GetRestrictedTelemetryDeps():
+  with open(_TELEMETRY_DEPS_PATH, 'r') as f:
+    telemetry_deps = json.load(f)
+
+  # Normalize paths in telemetry_deps since TELEMETRY_DEPS file only contain
+  # the relative path in chromium/src/.
+  def NormalizePath(p):
+    p = p.replace('/', os.path.sep)
+    return os.path.realpath(os.path.join(path.GetChromiumSrcDir(), p))
+
+  telemetry_deps['file_deps'] = [
+      NormalizePath(p) for p in telemetry_deps['file_deps']]
+  telemetry_deps['directory_deps'] = [
+      NormalizePath(p) for p in telemetry_deps['directory_deps']]
+  return telemetry_deps
+
+
+class TelemetryDependenciesTest(unittest.TestCase):
+
+  def testNoNewTelemetryDependencies(self):
+    telemetry_deps = _GetRestrictedTelemetryDeps()
+    current_dependencies = _GetCurrentTelemetryDependencies()
+    extra_dep_paths = []
+    for dep_path in current_dependencies:
+      if not (dep_path in telemetry_deps['file_deps'] or
+              any(path.IsSubpath(dep_path, d)
+                  for d in telemetry_deps['directory_deps'])):
+        extra_dep_paths.append(dep_path)
+    if extra_dep_paths:
+      self.fail(
+          'Your patch adds new dependencies to telemetry. Please contact '
+          'aiolos@,dtu@, or nednguyen@ on how to proceed with this change. '
+          'Extra dependencies:\n%s' % '\n'.join(extra_dep_paths))