diff --git a/services/surfaceflinger/DisplayHardware/ComposerHal.h b/services/surfaceflinger/DisplayHardware/ComposerHal.h
index 4372362..77675fb 100644
--- a/services/surfaceflinger/DisplayHardware/ComposerHal.h
+++ b/services/surfaceflinger/DisplayHardware/ComposerHal.h
@@ -26,6 +26,7 @@
 #include <android/frameworks/vr/composer/1.0/IVrComposerClient.h>
 #include <android/hardware/graphics/composer/2.1/IComposer.h>
 #include <composer-command-buffer/2.1/ComposerCommandBuffer.h>
+#include <ui/GraphicBuffer.h>
 #include <utils/StrongPointer.h>
 
 namespace android {
diff --git a/services/surfaceflinger/tests/unittests/Android.bp b/services/surfaceflinger/tests/unittests/Android.bp
index 72e0a0f..6151466 100644
--- a/services/surfaceflinger/tests/unittests/Android.bp
+++ b/services/surfaceflinger/tests/unittests/Android.bp
@@ -20,6 +20,7 @@
     srcs: [
         ":libsurfaceflinger_sources",
         "DisplayTransactionTest.cpp",
+        "MockComposer.cpp",
     ],
     static_libs: [
         "libgmock",
diff --git a/services/surfaceflinger/tests/unittests/MockComposer.cpp b/services/surfaceflinger/tests/unittests/MockComposer.cpp
new file mode 100644
index 0000000..318519b
--- /dev/null
+++ b/services/surfaceflinger/tests/unittests/MockComposer.cpp
@@ -0,0 +1,29 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "MockComposer.h"
+
+namespace android {
+namespace Hwc2 {
+namespace mock {
+
+// Explicit default instantiation is recommended.
+Composer::Composer() = default;
+Composer::~Composer() = default;
+
+} // namespace mock
+} // namespace Hwc2
+} // namespace android
diff --git a/services/surfaceflinger/tests/unittests/MockComposer.h b/services/surfaceflinger/tests/unittests/MockComposer.h
new file mode 100644
index 0000000..248afcf
--- /dev/null
+++ b/services/surfaceflinger/tests/unittests/MockComposer.h
@@ -0,0 +1,111 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <gmock/gmock.h>
+
+#include "DisplayHardware/ComposerHal.h"
+
+namespace android {
+
+class GraphicBuffer;
+
+namespace Hwc2 {
+namespace mock {
+
+using android::hardware::graphics::common::V1_0::ColorMode;
+using android::hardware::graphics::common::V1_0::ColorTransform;
+using android::hardware::graphics::common::V1_0::Dataspace;
+using android::hardware::graphics::common::V1_0::Hdr;
+using android::hardware::graphics::common::V1_0::PixelFormat;
+using android::hardware::graphics::common::V1_0::Transform;
+
+using android::hardware::graphics::composer::V2_1::Config;
+using android::hardware::graphics::composer::V2_1::Display;
+using android::hardware::graphics::composer::V2_1::Error;
+using android::hardware::graphics::composer::V2_1::IComposer;
+using android::hardware::graphics::composer::V2_1::IComposerCallback;
+using android::hardware::graphics::composer::V2_1::IComposerClient;
+using android::hardware::graphics::composer::V2_1::Layer;
+
+class Composer : public Hwc2::Composer {
+public:
+    Composer();
+    ~Composer() override;
+
+    MOCK_METHOD0(getCapabilities, std::vector<IComposer::Capability>());
+    MOCK_METHOD0(dumpDebugInfo, std::string());
+    MOCK_METHOD1(registerCallback, void(const sp<IComposerCallback>&));
+    MOCK_METHOD0(isRemote, bool());
+    MOCK_METHOD0(resetCommands, void());
+    MOCK_METHOD0(executeCommands, Error());
+    MOCK_METHOD0(getMaxVirtualDisplayCount, uint32_t());
+    MOCK_CONST_METHOD0(isUsingVrComposer, bool());
+    MOCK_METHOD4(createVirtualDisplay, Error(uint32_t, uint32_t, PixelFormat*, Display*));
+    MOCK_METHOD1(destroyVirtualDisplay, Error(Display));
+    MOCK_METHOD1(acceptDisplayChanges, Error(Display));
+    MOCK_METHOD2(createLayer, Error(Display, Layer* outLayer));
+    MOCK_METHOD2(destroyLayer, Error(Display, Layer));
+    MOCK_METHOD2(getActiveConfig, Error(Display, Config*));
+    MOCK_METHOD3(getChangedCompositionTypes,
+                 Error(Display, std::vector<Layer>*, std::vector<IComposerClient::Composition>*));
+    MOCK_METHOD2(getColorModes, Error(Display, std::vector<ColorMode>*));
+    MOCK_METHOD4(getDisplayAttribute,
+                 Error(Display, Config config, IComposerClient::Attribute, int32_t*));
+    MOCK_METHOD2(getDisplayConfigs, Error(Display, std::vector<Config>*));
+    MOCK_METHOD2(getDisplayName, Error(Display, std::string*));
+    MOCK_METHOD4(getDisplayRequests,
+                 Error(Display, uint32_t*, std::vector<Layer>*, std::vector<uint32_t>*));
+    MOCK_METHOD2(getDisplayType, Error(Display, IComposerClient::DisplayType*));
+    MOCK_METHOD2(getDozeSupport, Error(Display, bool*));
+    MOCK_METHOD5(getHdrCapabilities, Error(Display, std::vector<Hdr>*, float*, float*, float*));
+    MOCK_METHOD3(getReleaseFences, Error(Display, std::vector<Layer>*, std::vector<int>*));
+    MOCK_METHOD2(presentDisplay, Error(Display, int*));
+    MOCK_METHOD2(setActiveConfig, Error(Display, Config));
+    MOCK_METHOD6(setClientTarget,
+                 Error(Display, uint32_t, const sp<GraphicBuffer>&, int, Dataspace,
+                       const std::vector<IComposerClient::Rect>&));
+    MOCK_METHOD2(setColorMode, Error(Display, ColorMode));
+    MOCK_METHOD3(setColorTransform, Error(Display, const float*, ColorTransform));
+    MOCK_METHOD3(setOutputBuffer, Error(Display, const native_handle_t*, int));
+    MOCK_METHOD2(setPowerMode, Error(Display, IComposerClient::PowerMode));
+    MOCK_METHOD2(setVsyncEnabled, Error(Display, IComposerClient::Vsync));
+    MOCK_METHOD1(setClientTargetSlotCount, Error(Display));
+    MOCK_METHOD3(validateDisplay, Error(Display, uint32_t*, uint32_t*));
+    MOCK_METHOD5(presentOrValidateDisplay, Error(Display, uint32_t*, uint32_t*, int*, uint32_t*));
+    MOCK_METHOD4(setCursorPosition, Error(Display, Layer, int32_t, int32_t));
+    MOCK_METHOD5(setLayerBuffer, Error(Display, Layer, uint32_t, const sp<GraphicBuffer>&, int));
+    MOCK_METHOD3(setLayerSurfaceDamage,
+                 Error(Display, Layer, const std::vector<IComposerClient::Rect>&));
+    MOCK_METHOD3(setLayerBlendMode, Error(Display, Layer, IComposerClient::BlendMode));
+    MOCK_METHOD3(setLayerColor, Error(Display, Layer, const IComposerClient::Color&));
+    MOCK_METHOD3(setLayerCompositionType, Error(Display, Layer, IComposerClient::Composition));
+    MOCK_METHOD3(setLayerDataspace, Error(Display, Layer, Dataspace));
+    MOCK_METHOD3(setLayerDisplayFrame, Error(Display, Layer, const IComposerClient::Rect&));
+    MOCK_METHOD3(setLayerPlaneAlpha, Error(Display, Layer, float));
+    MOCK_METHOD3(setLayerSidebandStream, Error(Display, Layer, const native_handle_t*));
+    MOCK_METHOD3(setLayerSourceCrop, Error(Display, Layer, const IComposerClient::FRect&));
+    MOCK_METHOD3(setLayerTransform, Error(Display, Layer, Transform));
+    MOCK_METHOD3(setLayerVisibleRegion,
+                 Error(Display, Layer, const std::vector<IComposerClient::Rect>&));
+    MOCK_METHOD3(setLayerZOrder, Error(Display, Layer, uint32_t));
+    MOCK_METHOD4(setLayerInfo, Error(Display, Layer, uint32_t, uint32_t));
+};
+
+} // namespace mock
+} // namespace Hwc2
+} // namespace android