Add mock classes for Bus, ObjectProxy, and ExportedObject.

dbus/dbus.gyp

Index: dbus/dbus.gyp
diff --git a/dbus/dbus.gyp b/dbus/dbus.gyp
index 143f672ed38bb7af88da5502c96c836778b1f95b..c17aecf06ac5ec9b611933ed80d48cb059668b13 100644
--- a/dbus/dbus.gyp
+++ b/dbus/dbus.gyp
@@ -17,8 +17,8 @@
       'sources': [
         'bus.cc',
         'bus.h',
-        'exported_object.h',
         'exported_object.cc',
+        'exported_object.h',
         'message.cc',
         'message.h',
         'object_proxy.cc',
@@ -27,20 +27,43 @@
       ],
     },
     {
+      # This target contains mocks that can be used to write unit tests
+      # without issuing actual D-Bus calls.
+      'target_name': 'dbus_test_support',
+      'type': 'static_library',
+      'dependencies': [
+        '../build/linux/system.gyp:dbus',
+        '../testing/gmock.gyp:gmock',
+        'dbus',
+      ],
+      'sources': [
+        'mock_bus.cc',
+        'mock_bus.h',
+        'mock_object_proxy.cc',
+        'mock_object_proxy.h',
+      ],
+      'include_dirs': [
+        '..',
+      ],
+    },
+    {
       'target_name': 'dbus_unittests',
       'type': 'executable',
       'dependencies': [
-        'dbus',
         '../base/base.gyp:test_support_base',
-        '../testing/gtest.gyp:gtest',
         '../build/linux/system.gyp:dbus',
+        '../testing/gmock.gyp:gmock',
+        '../testing/gtest.gyp:gtest',
+        'dbus',
+        'dbus_test_support',
       ],
       'sources': [
         '../base/test/run_all_unittests.cc',
         'bus_unittest.cc',
-        'message_unittest.cc',
         'end_to_end_async_unittest.cc',
         'end_to_end_sync_unittest.cc',
+        'message_unittest.cc',
+        'mock_unittest.cc',
         'test_service.cc',
         'test_service.h',
       ],