1 files changed, 98 insertions, 0 deletions
diff --git a/catapult/telemetry/telemetry/testing/simple_mock.py b/catapult/telemetry/telemetry/testing/simple_mock.py
new file mode 100644
index 00000000..dbd02b68
--- /dev/null
+++ b/catapult/telemetry/telemetry/testing/simple_mock.py
@@ -0,0 +1,98 @@
+# Copyright 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.
+"""A very very simple mock object harness."""
+
+DONT_CARE = ''
+
+class MockFunctionCall(object):
+  def __init__(self, name):
+    self.name = name
+    self.args = tuple()
+    self.return_value = None
+    self.when_called_handlers = []
+
+  def WithArgs(self, *args):
+    self.args = args
+    return self
+
+  def WillReturn(self, value):
+    self.return_value = value
+    return self
+
+  def WhenCalled(self, handler):
+    self.when_called_handlers.append(handler)
+
+  def VerifyEquals(self, got):
+    if self.name != got.name:
+      raise Exception('Self %s, got %s' % (repr(self), repr(got)))
+    if len(self.args) != len(got.args):
+      raise Exception('Self %s, got %s' % (repr(self), repr(got)))
+    for i in range(len(self.args)):
+      self_a = self.args[i]
+      got_a = got.args[i]
+      if self_a == DONT_CARE:
+        continue
+      if self_a != got_a:
+        raise Exception('Self %s, got %s' % (repr(self), repr(got)))
+
+  def __repr__(self):
+    def arg_to_text(a):
+      if a == DONT_CARE:
+        return '_'
+      return repr(a)
+    args_text = ', '.join([arg_to_text(a) for a in self.args])
+    if self.return_value in (None, DONT_CARE):
+      return '%s(%s)' % (self.name, args_text)
+    return '%s(%s)->%s' % (self.name, args_text, repr(self.return_value))
+
+class MockTrace(object):
+  def __init__(self):
+    self.expected_calls = []
+    self.next_call_index = 0
+
+class MockObject(object):
+  def __init__(self, parent_mock=None):
+    if parent_mock:
+      self._trace = parent_mock._trace # pylint: disable=protected-access
+    else:
+      self._trace = MockTrace()
+
+  def __setattr__(self, name, value):
+    if (not hasattr(self, '_trace') or
+        hasattr(value, 'is_hook')):
+      object.__setattr__(self, name, value)
+      return
+    assert isinstance(value, MockObject)
+    object.__setattr__(self, name, value)
+
+  def SetAttribute(self, name, value):
+    setattr(self, name, value)
+
+  def ExpectCall(self, func_name, *args):
+    assert self._trace.next_call_index == 0
+    if not hasattr(self, func_name):
+      self._install_hook(func_name)
+
+    call = MockFunctionCall(func_name)
+    self._trace.expected_calls.append(call)
+    call.WithArgs(*args)
+    return call
+
+  def _install_hook(self, func_name):
+    def handler(*args, **_):
+      got_call = MockFunctionCall(
+        func_name).WithArgs(*args).WillReturn(DONT_CARE)
+      if self._trace.next_call_index >= len(self._trace.expected_calls):
+        raise Exception(
+          'Call to %s was not expected, at end of programmed trace.' %
+          repr(got_call))
+      expected_call = self._trace.expected_calls[
+        self._trace.next_call_index]
+      expected_call.VerifyEquals(got_call)
+      self._trace.next_call_index += 1
+      for h in expected_call.when_called_handlers:
+        h(*args)
+      return expected_call.return_value
+    handler.is_hook = True
+    setattr(self, func_name, handler)