diff --git a/services/surfaceflinger/tests/unittests/Android.bp b/services/surfaceflinger/tests/unittests/Android.bp
index d046f76..1cd8731 100644
--- a/services/surfaceflinger/tests/unittests/Android.bp
+++ b/services/surfaceflinger/tests/unittests/Android.bp
@@ -42,6 +42,7 @@
         "DisplayTransactionTest.cpp",
         "EventControlThreadTest.cpp",
         "EventThreadTest.cpp",
+        "HWComposerTest.cpp",
         "OneShotTimerTest.cpp",
         "LayerHistoryTest.cpp",
         "LayerHistoryTestV2.cpp",
diff --git a/services/surfaceflinger/tests/unittests/CompositionTest.cpp b/services/surfaceflinger/tests/unittests/CompositionTest.cpp
index 888e009..b41131b 100644
--- a/services/surfaceflinger/tests/unittests/CompositionTest.cpp
+++ b/services/surfaceflinger/tests/unittests/CompositionTest.cpp
@@ -116,8 +116,6 @@
 
     void setupComposer(int virtualDisplayCount) {
         mComposer = new Hwc2::mock::Composer();
-        EXPECT_CALL(*mComposer, getCapabilities())
-                .WillOnce(Return(std::vector<IComposer::Capability>()));
         EXPECT_CALL(*mComposer, getMaxVirtualDisplayCount()).WillOnce(Return(virtualDisplayCount));
         mFlinger.setupComposer(std::unique_ptr<Hwc2::Composer>(mComposer));
 
diff --git a/services/surfaceflinger/tests/unittests/DisplayTransactionTest.cpp b/services/surfaceflinger/tests/unittests/DisplayTransactionTest.cpp
index dddad92..232255f 100644
--- a/services/surfaceflinger/tests/unittests/DisplayTransactionTest.cpp
+++ b/services/surfaceflinger/tests/unittests/DisplayTransactionTest.cpp
@@ -201,8 +201,6 @@
 
 void DisplayTransactionTest::injectMockComposer(int virtualDisplayCount) {
     mComposer = new Hwc2::mock::Composer();
-    EXPECT_CALL(*mComposer, getCapabilities())
-            .WillOnce(Return(std::vector<IComposer::Capability>()));
     EXPECT_CALL(*mComposer, getMaxVirtualDisplayCount()).WillOnce(Return(virtualDisplayCount));
     mFlinger.setupComposer(std::unique_ptr<Hwc2::Composer>(mComposer));
 
diff --git a/services/surfaceflinger/tests/unittests/HWComposerTest.cpp b/services/surfaceflinger/tests/unittests/HWComposerTest.cpp
new file mode 100644
index 0000000..c6fe205
--- /dev/null
+++ b/services/surfaceflinger/tests/unittests/HWComposerTest.cpp
@@ -0,0 +1,176 @@
+/*
+ * Copyright 2020 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.
+ */
+
+// TODO(b/129481165): remove the #pragma below and fix conversion issues
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wconversion"
+
+#undef LOG_TAG
+#define LOG_TAG "LibSurfaceFlingerUnittests"
+
+#include <vector>
+
+#include <gmock/gmock.h>
+#include <gui/LayerMetadata.h>
+#include <log/log.h>
+
+#include "DisplayHardware/HWComposer.h"
+#include "mock/DisplayHardware/MockComposer.h"
+
+// TODO(b/129481165): remove the #pragma below and fix conversion issues
+#pragma clang diagnostic pop // ignored "-Wconversion"
+
+namespace android {
+namespace {
+
+using ::testing::_;
+using ::testing::DoAll;
+using ::testing::ElementsAreArray;
+using ::testing::Return;
+using ::testing::SetArgPointee;
+using ::testing::StrictMock;
+
+struct MockHWC2ComposerCallback : public HWC2::ComposerCallback {
+    ~MockHWC2ComposerCallback() = default;
+
+    MOCK_METHOD3(onHotplugReceived,
+                 void(int32_t sequenceId, hwc2_display_t display, HWC2::Connection connection));
+    MOCK_METHOD2(onRefreshReceived, void(int32_t sequenceId, hwc2_display_t display));
+    MOCK_METHOD4(onVsyncReceived,
+                 void(int32_t sequenceId, hwc2_display_t display, int64_t timestamp,
+                      std::optional<hwc2_vsync_period_t> vsyncPeriod));
+    MOCK_METHOD3(onVsyncPeriodTimingChangedReceived,
+                 void(int32_t sequenceId, hwc2_display_t display,
+                      const hwc_vsync_period_change_timeline_t& updatedTimeline));
+    MOCK_METHOD2(onSeamlessPossible, void(int32_t sequenceId, hwc2_display_t display));
+};
+
+struct HWComposerTest : public testing::Test {
+    Hwc2::mock::Composer* mHal = new StrictMock<Hwc2::mock::Composer>();
+};
+
+struct HWComposerSetConfigurationTest : public HWComposerTest {
+    StrictMock<MockHWC2ComposerCallback> mCallback;
+};
+
+TEST_F(HWComposerSetConfigurationTest, loadsLayerMetadataSupport) {
+    const std::string kMetadata1Name = "com.example.metadata.1";
+    constexpr bool kMetadata1Mandatory = false;
+    const std::string kMetadata2Name = "com.example.metadata.2";
+    constexpr bool kMetadata2Mandatory = true;
+
+    EXPECT_CALL(*mHal, getMaxVirtualDisplayCount()).WillOnce(Return(0));
+    EXPECT_CALL(*mHal, getCapabilities())
+            .WillOnce(Return(std::vector<Hwc2::IComposer::Capability>{}));
+    EXPECT_CALL(*mHal, getLayerGenericMetadataKeys(_))
+            .WillOnce(DoAll(SetArgPointee<0>(
+                                    std::vector<Hwc2::IComposerClient::LayerGenericMetadataKey>{
+                                            {kMetadata1Name, kMetadata1Mandatory},
+                                            {kMetadata2Name, kMetadata2Mandatory},
+                                    }),
+                            Return(hardware::graphics::composer::V2_4::Error::NONE)));
+    EXPECT_CALL(*mHal, registerCallback(_));
+    EXPECT_CALL(*mHal, isVsyncPeriodSwitchSupported()).WillOnce(Return(false));
+
+    impl::HWComposer hwc{std::unique_ptr<Hwc2::Composer>(mHal)};
+    hwc.setConfiguration(&mCallback, 123);
+
+    const auto& supported = hwc.getSupportedLayerGenericMetadata();
+    EXPECT_EQ(2u, supported.size());
+    EXPECT_EQ(1u, supported.count(kMetadata1Name));
+    EXPECT_EQ(kMetadata1Mandatory, supported.find(kMetadata1Name)->second);
+    EXPECT_EQ(1u, supported.count(kMetadata2Name));
+    EXPECT_EQ(kMetadata2Mandatory, supported.find(kMetadata2Name)->second);
+}
+
+TEST_F(HWComposerSetConfigurationTest, handlesUnsupportedCallToGetLayerGenericMetadataKeys) {
+    EXPECT_CALL(*mHal, getMaxVirtualDisplayCount()).WillOnce(Return(0));
+    EXPECT_CALL(*mHal, getCapabilities())
+            .WillOnce(Return(std::vector<Hwc2::IComposer::Capability>{}));
+    EXPECT_CALL(*mHal, getLayerGenericMetadataKeys(_))
+            .WillOnce(Return(hardware::graphics::composer::V2_4::Error::UNSUPPORTED));
+    EXPECT_CALL(*mHal, registerCallback(_));
+    EXPECT_CALL(*mHal, isVsyncPeriodSwitchSupported()).WillOnce(Return(false));
+
+    impl::HWComposer hwc{std::unique_ptr<Hwc2::Composer>(mHal)};
+    hwc.setConfiguration(&mCallback, 123);
+
+    const auto& supported = hwc.getSupportedLayerGenericMetadata();
+    EXPECT_EQ(0u, supported.size());
+}
+
+struct HWComposerLayerTest : public testing::Test {
+    static constexpr hwc2_display_t kDisplayId = static_cast<hwc2_display_t>(1001);
+    static constexpr hwc2_layer_t kLayerId = static_cast<hwc2_layer_t>(1002);
+
+    HWComposerLayerTest(const std::unordered_set<HWC2::Capability>& capabilities)
+          : mCapabilies(capabilities) {}
+
+    ~HWComposerLayerTest() override { EXPECT_CALL(*mHal, destroyLayer(kDisplayId, kLayerId)); }
+
+    std::unique_ptr<Hwc2::mock::Composer> mHal{new StrictMock<Hwc2::mock::Composer>()};
+    const std::unordered_set<HWC2::Capability> mCapabilies;
+    HWC2::impl::Layer mLayer{*mHal, mCapabilies, kDisplayId, kLayerId};
+};
+
+struct HWComposerLayerGenericMetadataTest : public HWComposerLayerTest {
+    static const std::string kLayerGenericMetadata1Name;
+    static constexpr bool kLayerGenericMetadata1Mandatory = false;
+    static const std::vector<uint8_t> kLayerGenericMetadata1Value;
+    static const std::string kLayerGenericMetadata2Name;
+    static constexpr bool kLayerGenericMetadata2Mandatory = true;
+    static const std::vector<uint8_t> kLayerGenericMetadata2Value;
+
+    HWComposerLayerGenericMetadataTest() : HWComposerLayerTest({}) {}
+};
+
+const std::string HWComposerLayerGenericMetadataTest::kLayerGenericMetadata1Name =
+        "com.example.metadata.1";
+
+const std::vector<uint8_t> HWComposerLayerGenericMetadataTest::kLayerGenericMetadata1Value = {1u,
+                                                                                              2u,
+                                                                                              3u};
+
+const std::string HWComposerLayerGenericMetadataTest::kLayerGenericMetadata2Name =
+        "com.example.metadata.2";
+
+const std::vector<uint8_t> HWComposerLayerGenericMetadataTest::kLayerGenericMetadata2Value = {45u,
+                                                                                              67u};
+
+TEST_F(HWComposerLayerGenericMetadataTest, forwardsSupportedMetadata) {
+    EXPECT_CALL(*mHal,
+                setLayerGenericMetadata(kDisplayId, kLayerId, kLayerGenericMetadata1Name,
+                                        kLayerGenericMetadata1Mandatory,
+                                        kLayerGenericMetadata1Value))
+            .WillOnce(Return(hardware::graphics::composer::V2_4::Error::NONE));
+    auto result = mLayer.setLayerGenericMetadata(kLayerGenericMetadata1Name,
+                                                 kLayerGenericMetadata1Mandatory,
+                                                 kLayerGenericMetadata1Value);
+    EXPECT_EQ(HWC2::Error::None, result);
+
+    EXPECT_CALL(*mHal,
+                setLayerGenericMetadata(kDisplayId, kLayerId, kLayerGenericMetadata2Name,
+                                        kLayerGenericMetadata2Mandatory,
+                                        kLayerGenericMetadata2Value))
+            .WillOnce(Return(hardware::graphics::composer::V2_4::Error::UNSUPPORTED));
+    result = mLayer.setLayerGenericMetadata(kLayerGenericMetadata2Name,
+                                            kLayerGenericMetadata2Mandatory,
+                                            kLayerGenericMetadata2Value);
+    EXPECT_EQ(HWC2::Error::Unsupported, result);
+}
+
+} // namespace
+} // namespace android
diff --git a/services/surfaceflinger/tests/unittests/RefreshRateSelectionTest.cpp b/services/surfaceflinger/tests/unittests/RefreshRateSelectionTest.cpp
index cffdc14..d8e8724 100644
--- a/services/surfaceflinger/tests/unittests/RefreshRateSelectionTest.cpp
+++ b/services/surfaceflinger/tests/unittests/RefreshRateSelectionTest.cpp
@@ -153,8 +153,6 @@
 
 void RefreshRateSelectionTest::setupComposer(int virtualDisplayCount) {
     mComposer = new Hwc2::mock::Composer();
-    EXPECT_CALL(*mComposer, getCapabilities())
-            .WillOnce(Return(std::vector<IComposer::Capability>()));
     EXPECT_CALL(*mComposer, getMaxVirtualDisplayCount()).WillOnce(Return(virtualDisplayCount));
     mFlinger.setupComposer(std::unique_ptr<Hwc2::Composer>(mComposer));