diff --git a/automotive/vehicle/aidl/impl/fake_impl/userhal/Android.bp b/automotive/vehicle/aidl/impl/fake_impl/userhal/Android.bp
new file mode 100644
index 0000000..2e95531
--- /dev/null
+++ b/automotive/vehicle/aidl/impl/fake_impl/userhal/Android.bp
@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2021 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.
+ */
+
+package {
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
+cc_library {
+    name: "FakeUserHal",
+    vendor: true,
+    srcs: ["src/*.cpp"],
+    local_include_dirs: ["include"],
+    export_include_dirs: ["include"],
+    defaults: ["VehicleHalDefaults"],
+    static_libs: [
+        "VehicleHalUtils",
+    ],
+    export_static_lib_headers: ["VehicleHalUtils"],
+}
diff --git a/automotive/vehicle/aidl/impl/fake_impl/userhal/include/FakeUserHal.h b/automotive/vehicle/aidl/impl/fake_impl/userhal/include/FakeUserHal.h
new file mode 100644
index 0000000..1424c81
--- /dev/null
+++ b/automotive/vehicle/aidl/impl/fake_impl/userhal/include/FakeUserHal.h
@@ -0,0 +1,132 @@
+/*
+ * Copyright (C) 2021 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.
+ */
+
+#ifndef android_hardware_automotive_vehicle_aidl_impl_fake_impl_userhal_include_FakeUserHal_H_
+#define android_hardware_automotive_vehicle_aidl_impl_fake_impl_userhal_include_FakeUserHal_H_
+
+#include <android-base/format.h>
+#include <android-base/result.h>
+#include <android-base/thread_annotations.h>
+
+#include <VehicleHalTypes.h>
+#include <VehicleObjectPool.h>
+
+#include <memory>
+#include <mutex>
+
+namespace android {
+namespace hardware {
+namespace automotive {
+namespace vehicle {
+namespace fake {
+
+constexpr char kUserHalDumpOption[] = "--user-hal";
+
+// Class used to emulate a real User HAL behavior through lshal debug requests.
+class FakeUserHal final {
+  public:
+    explicit FakeUserHal(std::shared_ptr<VehiclePropValuePool> valuePool) : mValuePool(valuePool) {}
+
+    ~FakeUserHal() = default;
+
+    // Checks if the emulator can handle the property.
+    static bool isSupported(int32_t prop);
+
+    // Lets the emulator set the property.
+    //
+    // @return updated property and StatusCode
+    android::base::Result<VehiclePropValuePool::RecyclableType> onSetProperty(
+            const ::aidl::android::hardware::automotive::vehicle::VehiclePropValue& value);
+
+    // Gets the property value from the emulator.
+    //
+    // @return property value and StatusCode
+    android::base::Result<VehiclePropValuePool::RecyclableType> onGetProperty(
+            const ::aidl::android::hardware::automotive::vehicle::VehiclePropValue& value) const;
+
+    // Shows the User HAL emulation help.
+    std::string showDumpHelp() const;
+
+    // Dump its contents.
+    std::string dump(std::string indent) const;
+
+  private:
+    const std::shared_ptr<VehiclePropValuePool> mValuePool;
+    mutable std::mutex mLock;
+    VehiclePropValuePool::RecyclableType mInitialUserResponseFromCmd GUARDED_BY(mLock);
+    VehiclePropValuePool::RecyclableType mSwitchUserResponseFromCmd GUARDED_BY(mLock);
+    VehiclePropValuePool::RecyclableType mCreateUserResponseFromCmd GUARDED_BY(mLock);
+    VehiclePropValuePool::RecyclableType mSetUserIdentificationAssociationResponseFromCmd
+            GUARDED_BY(mLock);
+
+    // INITIAL_USER_INFO is called by Android when it starts, and it's expecting a property change
+    // indicating what the initial user should be.
+    //
+    // During normal circumstances, the emulator will reply right away, passing a response if
+    // InitialUserInfoResponseAction::DEFAULT (so Android could use its own logic to decide which
+    // user to boot).
+    //
+    // But during development / testing, the behavior can be changed using lshal dump, which must
+    // use the areaId to indicate what should happen next.
+    //
+    // So, the behavior of set(INITIAL_USER_INFO) is:
+    //
+    // - if it has an areaId, store the property into mInitialUserResponseFromCmd (as it was called
+    // by lshal).
+    // - else if mInitialUserResponseFromCmd is not set, return a response with the same request id
+    // and InitialUserInfoResponseAction::DEFAULT
+    // - else the behavior is defined by the areaId on mInitialUserResponseFromCmd:
+    // - if it's 1, reply with mInitialUserResponseFromCmd and the right request id
+    // - if it's 2, reply with mInitialUserResponseFromCmd but a wrong request id (so Android can
+    // test this error scenario)
+    // - if it's 3, then don't send a property change (so Android can emulate a timeout)
+    android::base::Result<VehiclePropValuePool::RecyclableType> onSetInitialUserInfoResponse(
+            const ::aidl::android::hardware::automotive::vehicle::VehiclePropValue& value);
+
+    // Used to emulate SWITCH_USER - see onSetInitialUserInfoResponse() for usage.
+    android::base::Result<VehiclePropValuePool::RecyclableType> onSetSwitchUserResponse(
+            const ::aidl::android::hardware::automotive::vehicle::VehiclePropValue& value);
+
+    // Used to emulate CREATE_USER - see onSetInitialUserInfoResponse() for usage.
+    android::base::Result<VehiclePropValuePool::RecyclableType> onSetCreateUserResponse(
+            const ::aidl::android::hardware::automotive::vehicle::VehiclePropValue& value);
+
+    // Used to emulate set USER_IDENTIFICATION_ASSOCIATION - see onSetInitialUserInfoResponse() for
+    // usage.
+    android::base::Result<VehiclePropValuePool::RecyclableType> onSetUserIdentificationAssociation(
+            const ::aidl::android::hardware::automotive::vehicle::VehiclePropValue& value);
+
+    // Used to emulate get USER_IDENTIFICATION_ASSOCIATION - see onSetInitialUserInfoResponse() for
+    // usage.
+    android::base::Result<VehiclePropValuePool::RecyclableType> onGetUserIdentificationAssociation(
+            const ::aidl::android::hardware::automotive::vehicle::VehiclePropValue& value) const;
+
+    // Creates a default USER_IDENTIFICATION_ASSOCIATION when it was not set by lshal.
+    static android::base::Result<VehiclePropValuePool::RecyclableType>
+    defaultUserIdentificationAssociation(
+            const ::aidl::android::hardware::automotive::vehicle::VehiclePropValue& request);
+
+    android::base::Result<VehiclePropValuePool::RecyclableType> sendUserHalResponse(
+            VehiclePropValuePool::RecyclableType response, int32_t requestId);
+};
+
+}  // namespace fake
+}  // namespace vehicle
+}  // namespace automotive
+}  // namespace hardware
+}  // namespace android
+
+#endif  // android_hardware_automotive_vehicle_aidl_impl_fake_impl_userhal_include_FakeUserHal_H_
diff --git a/automotive/vehicle/aidl/impl/fake_impl/userhal/include/UserHalHelper.h b/automotive/vehicle/aidl/impl/fake_impl/userhal/include/UserHalHelper.h
new file mode 100644
index 0000000..5be13be
--- /dev/null
+++ b/automotive/vehicle/aidl/impl/fake_impl/userhal/include/UserHalHelper.h
@@ -0,0 +1,88 @@
+/*
+ * Copyright (C) 2021 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.
+ */
+
+#ifndef android_hardware_automotive_vehicle_aidl_impl_fake_impl_userhal_include_UserHalHelper_H_
+#define android_hardware_automotive_vehicle_aidl_impl_fake_impl_userhal_include_UserHalHelper_H_
+
+#include <UserHalTypes.h>
+#include <VehicleHalTypes.h>
+#include <VehicleObjectPool.h>
+#include <android-base/result.h>
+
+#include <functional>
+#include <memory>
+
+namespace android {
+namespace hardware {
+namespace automotive {
+namespace vehicle {
+namespace fake {
+namespace user_hal_helper {
+
+// Verify whether the |value| can be casted to the type |T| and return the casted value on success.
+// Otherwise, return the error.
+template <typename T>
+::android::base::Result<T> verifyAndCast(int32_t value);
+
+// Below functions parse VehiclePropValues to the respective User HAL request structs. On success,
+// these functions return the User HAL struct. Otherwise, they return the error.
+::android::base::Result<::aidl::android::hardware::automotive::vehicle::InitialUserInfoRequest>
+toInitialUserInfoRequest(
+        const ::aidl::android::hardware::automotive::vehicle::VehiclePropValue& propValue);
+::android::base::Result<::aidl::android::hardware::automotive::vehicle::SwitchUserRequest>
+toSwitchUserRequest(
+        const ::aidl::android::hardware::automotive::vehicle::VehiclePropValue& propValue);
+::android::base::Result<::aidl::android::hardware::automotive::vehicle::CreateUserRequest>
+toCreateUserRequest(
+        const ::aidl::android::hardware::automotive::vehicle::VehiclePropValue& propValue);
+::android::base::Result<::aidl::android::hardware::automotive::vehicle::RemoveUserRequest>
+toRemoveUserRequest(
+        const ::aidl::android::hardware::automotive::vehicle::VehiclePropValue& propValue);
+::android::base::Result<
+        ::aidl::android::hardware::automotive::vehicle::UserIdentificationGetRequest>
+toUserIdentificationGetRequest(
+        const ::aidl::android::hardware::automotive::vehicle::VehiclePropValue& propValue);
+::android::base::Result<
+        ::aidl::android::hardware::automotive::vehicle::UserIdentificationSetRequest>
+toUserIdentificationSetRequest(
+        const ::aidl::android::hardware::automotive::vehicle::VehiclePropValue& propValue);
+
+// Below functions convert the User HAL structs to VehiclePropValues. On success, these functions
+// return the pointer to VehiclePropValue. Otherwise, they return the error.
+::android::base::Result<VehiclePropValuePool::RecyclableType> toVehiclePropValue(
+        VehiclePropValuePool& pool,
+        const ::aidl::android::hardware::automotive::vehicle::SwitchUserRequest& request);
+VehiclePropValuePool::RecyclableType toVehiclePropValue(
+        VehiclePropValuePool& pool,
+        const ::aidl::android::hardware::automotive::vehicle::InitialUserInfoResponse& response);
+VehiclePropValuePool::RecyclableType toVehiclePropValue(
+        VehiclePropValuePool& pool,
+        const ::aidl::android::hardware::automotive::vehicle::SwitchUserResponse& response);
+VehiclePropValuePool::RecyclableType toVehiclePropValue(
+        VehiclePropValuePool& pool,
+        const ::aidl::android::hardware::automotive::vehicle::CreateUserResponse& response);
+VehiclePropValuePool::RecyclableType toVehiclePropValue(
+        VehiclePropValuePool& pool,
+        const ::aidl::android::hardware::automotive::vehicle::UserIdentificationResponse& response);
+
+}  // namespace user_hal_helper
+}  // namespace fake
+}  // namespace vehicle
+}  // namespace automotive
+}  // namespace hardware
+}  // namespace android
+
+#endif  // android_hardware_automotive_vehicle_aidl_impl_fake_impl_userhal_include_UserHalHelper_H_
diff --git a/automotive/vehicle/aidl/impl/fake_impl/userhal/include/UserHalTypes.h b/automotive/vehicle/aidl/impl/fake_impl/userhal/include/UserHalTypes.h
new file mode 100644
index 0000000..b5e17b3
--- /dev/null
+++ b/automotive/vehicle/aidl/impl/fake_impl/userhal/include/UserHalTypes.h
@@ -0,0 +1,37 @@
+/*
+ * Copyright (C) 2021 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.
+ */
+
+#ifndef android_hardware_automotive_vehicle_aidl_impl_fake_impl_userhal_include_UserHalTypes_H_
+#define android_hardware_automotive_vehicle_aidl_impl_fake_impl_userhal_include_UserHalTypes_H_
+
+#include <aidl/android/hardware/automotive/vehicle/CreateUserRequest.h>
+#include <aidl/android/hardware/automotive/vehicle/CreateUserResponse.h>
+#include <aidl/android/hardware/automotive/vehicle/CreateUserStatus.h>
+#include <aidl/android/hardware/automotive/vehicle/InitialUserInfoRequest.h>
+#include <aidl/android/hardware/automotive/vehicle/InitialUserInfoRequestType.h>
+#include <aidl/android/hardware/automotive/vehicle/InitialUserInfoResponse.h>
+#include <aidl/android/hardware/automotive/vehicle/RemoveUserRequest.h>
+#include <aidl/android/hardware/automotive/vehicle/SwitchUserMessageType.h>
+#include <aidl/android/hardware/automotive/vehicle/SwitchUserRequest.h>
+#include <aidl/android/hardware/automotive/vehicle/SwitchUserResponse.h>
+#include <aidl/android/hardware/automotive/vehicle/SwitchUserStatus.h>
+#include <aidl/android/hardware/automotive/vehicle/UserIdentificationGetRequest.h>
+#include <aidl/android/hardware/automotive/vehicle/UserIdentificationResponse.h>
+#include <aidl/android/hardware/automotive/vehicle/UserIdentificationSetRequest.h>
+#include <aidl/android/hardware/automotive/vehicle/UserInfo.h>
+#include <aidl/android/hardware/automotive/vehicle/UsersInfo.h>
+
+#endif  // android_hardware_automotive_vehicle_aidl_impl_fake_impl_userhal_include_UserHalTypes_H_
diff --git a/automotive/vehicle/aidl/impl/fake_impl/userhal/src/FakeUserHal.cpp b/automotive/vehicle/aidl/impl/fake_impl/userhal/src/FakeUserHal.cpp
new file mode 100644
index 0000000..9b60053
--- /dev/null
+++ b/automotive/vehicle/aidl/impl/fake_impl/userhal/src/FakeUserHal.cpp
@@ -0,0 +1,374 @@
+/*
+ * Copyright (C) 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.
+ */
+#define LOG_TAG "FakeUserHal"
+
+#include "FakeUserHal.h"
+
+#include "UserHalHelper.h"
+
+#include <VehicleUtils.h>
+#include <utils/Log.h>
+#include <utils/SystemClock.h>
+
+namespace android {
+namespace hardware {
+namespace automotive {
+namespace vehicle {
+namespace fake {
+
+namespace {
+
+using ::aidl::android::hardware::automotive::vehicle::CreateUserResponse;
+using ::aidl::android::hardware::automotive::vehicle::CreateUserStatus;
+using ::aidl::android::hardware::automotive::vehicle::InitialUserInfoResponse;
+using ::aidl::android::hardware::automotive::vehicle::InitialUserInfoResponseAction;
+using ::aidl::android::hardware::automotive::vehicle::StatusCode;
+using ::aidl::android::hardware::automotive::vehicle::SwitchUserMessageType;
+using ::aidl::android::hardware::automotive::vehicle::SwitchUserResponse;
+using ::aidl::android::hardware::automotive::vehicle::SwitchUserStatus;
+using ::aidl::android::hardware::automotive::vehicle::VehicleProperty;
+using ::aidl::android::hardware::automotive::vehicle::VehiclePropValue;
+using ::android::base::Error;
+using ::android::base::Result;
+
+constexpr int32_t INITIAL_USER_INFO = toInt(VehicleProperty::INITIAL_USER_INFO);
+constexpr int32_t SWITCH_USER = toInt(VehicleProperty::SWITCH_USER);
+constexpr int32_t CREATE_USER = toInt(VehicleProperty::CREATE_USER);
+constexpr int32_t REMOVE_USER = toInt(VehicleProperty::REMOVE_USER);
+constexpr int32_t USER_IDENTIFICATION_ASSOCIATION =
+        toInt(VehicleProperty::USER_IDENTIFICATION_ASSOCIATION);
+
+Result<int32_t> getRequestId(const VehiclePropValue& value) {
+    if (value.value.int32Values.size() < 1) {
+        return Error(toInt(StatusCode::INVALID_ARG))
+               << "no int32Values on property: " << value.toString();
+    }
+    return value.value.int32Values[0];
+}
+
+Result<SwitchUserMessageType> getSwitchUserMessageType(const VehiclePropValue& value) {
+    if (value.value.int32Values.size() < 2) {
+        return Error(toInt(StatusCode::INVALID_ARG))
+               << "missing switch user message type on property: " << value.toString();
+    }
+    return user_hal_helper::verifyAndCast<SwitchUserMessageType>(value.value.int32Values[1]);
+}
+
+}  // namespace
+
+bool FakeUserHal::isSupported(int32_t prop) {
+    switch (prop) {
+        case INITIAL_USER_INFO:
+        case SWITCH_USER:
+        case CREATE_USER:
+        case REMOVE_USER:
+        case USER_IDENTIFICATION_ASSOCIATION:
+            return true;
+        default:
+            return false;
+    }
+}
+
+Result<VehiclePropValuePool::RecyclableType> FakeUserHal::onSetProperty(
+        const VehiclePropValue& value) {
+    ALOGV("onSetProperty(): %s", value.toString().c_str());
+
+    switch (value.prop) {
+        case INITIAL_USER_INFO:
+            return onSetInitialUserInfoResponse(value);
+        case SWITCH_USER:
+            return onSetSwitchUserResponse(value);
+        case CREATE_USER:
+            return onSetCreateUserResponse(value);
+        case REMOVE_USER:
+            ALOGI("REMOVE_USER is FYI only, nothing to do...");
+            return nullptr;
+        case USER_IDENTIFICATION_ASSOCIATION:
+            return onSetUserIdentificationAssociation(value);
+        default:
+            return Error(toInt(StatusCode::INVALID_ARG))
+                   << "Unsupported property: " << value.toString();
+    }
+}
+
+Result<VehiclePropValuePool::RecyclableType> FakeUserHal::onGetProperty(
+        const VehiclePropValue& value) const {
+    ALOGV("onGetProperty(%s)", value.toString().c_str());
+    switch (value.prop) {
+        case INITIAL_USER_INFO:
+        case SWITCH_USER:
+        case CREATE_USER:
+        case REMOVE_USER:
+            ALOGE("onGetProperty(): %d is only supported on SET", value.prop);
+            return Error(toInt(StatusCode::INVALID_ARG)) << "only supported on SET";
+        case USER_IDENTIFICATION_ASSOCIATION:
+            return onGetUserIdentificationAssociation(value);
+        default:
+            ALOGE("onGetProperty(): %d is not supported", value.prop);
+            return Error(toInt(StatusCode::INVALID_ARG)) << "not supported by User HAL";
+    }
+}
+
+Result<VehiclePropValuePool::RecyclableType> FakeUserHal::onGetUserIdentificationAssociation(
+        const VehiclePropValue& value) const {
+    std::scoped_lock<std::mutex> lockGuard(mLock);
+
+    if (mSetUserIdentificationAssociationResponseFromCmd == nullptr) {
+        return defaultUserIdentificationAssociation(value);
+    }
+    ALOGI("get(USER_IDENTIFICATION_ASSOCIATION): returning %s",
+          mSetUserIdentificationAssociationResponseFromCmd->toString().c_str());
+    auto newValue = mValuePool->obtain(*mSetUserIdentificationAssociationResponseFromCmd);
+    auto requestId = getRequestId(value);
+    if (requestId.ok()) {
+        // Must use the same requestId
+        newValue->value.int32Values[0] = *requestId;
+    } else {
+        ALOGE("get(USER_IDENTIFICATION_ASSOCIATION): no requestId on %s", value.toString().c_str());
+        return requestId.error();
+    }
+    return newValue;
+}
+
+Result<VehiclePropValuePool::RecyclableType> FakeUserHal::onSetInitialUserInfoResponse(
+        const VehiclePropValue& value) {
+    std::scoped_lock<std::mutex> lockGuard(mLock);
+
+    auto requestId = getRequestId(value);
+    if (!requestId.ok()) {
+        ALOGE("Failed to get requestId on set(INITIAL_USER_INFO): %s",
+              requestId.error().message().c_str());
+        return requestId.error();
+    }
+
+    if (value.areaId != 0) {
+        ALOGD("set(INITIAL_USER_INFO) called from lshal; storing it: %s", value.toString().c_str());
+        mInitialUserResponseFromCmd = mValuePool->obtain(value);
+        return nullptr;
+    }
+
+    ALOGD("set(INITIAL_USER_INFO) called from Android: %s", value.toString().c_str());
+    if (mInitialUserResponseFromCmd != nullptr) {
+        ALOGI("replying INITIAL_USER_INFO with lshal value: %s",
+              mInitialUserResponseFromCmd->toString().c_str());
+        return sendUserHalResponse(std::move(mInitialUserResponseFromCmd), *requestId);
+    }
+
+    // Returns default response
+    auto updatedValue = user_hal_helper::toVehiclePropValue(
+            *mValuePool, InitialUserInfoResponse{
+                                 .requestId = *requestId,
+                                 .action = InitialUserInfoResponseAction::DEFAULT,
+                         });
+    ALOGI("no lshal response; replying with InitialUserInfoResponseAction::DEFAULT: %s",
+          updatedValue->toString().c_str());
+    return updatedValue;
+}
+
+Result<VehiclePropValuePool::RecyclableType> FakeUserHal::onSetSwitchUserResponse(
+        const VehiclePropValue& value) {
+    std::scoped_lock<std::mutex> lockGuard(mLock);
+
+    auto requestId = getRequestId(value);
+    if (!requestId.ok()) {
+        ALOGE("Failed to get requestId on set(SWITCH_USER): %s",
+              requestId.error().message().c_str());
+        return requestId.error();
+    }
+
+    auto messageType = getSwitchUserMessageType(value);
+    if (!messageType.ok()) {
+        ALOGE("Failed to get messageType on set(SWITCH_USER): %s",
+              messageType.error().message().c_str());
+        return messageType.error();
+    }
+
+    if (value.areaId != 0) {
+        if (*messageType == SwitchUserMessageType::VEHICLE_REQUEST) {
+            // User HAL can also request a user switch, so we need to check it first
+            ALOGD("set(SWITCH_USER) called from lshal to emulate a vehicle request: %s",
+                  value.toString().c_str());
+            return mValuePool->obtain(value);
+        }
+        // Otherwise, we store it
+        ALOGD("set(SWITCH_USER) called from lshal; storing it: %s", value.toString().c_str());
+        mSwitchUserResponseFromCmd = mValuePool->obtain(value);
+        return nullptr;
+    }
+    ALOGD("set(SWITCH_USER) called from Android: %s", value.toString().c_str());
+
+    if (mSwitchUserResponseFromCmd != nullptr) {
+        ALOGI("replying SWITCH_USER with lshal value:  %s",
+              mSwitchUserResponseFromCmd->toString().c_str());
+        return sendUserHalResponse(std::move(mSwitchUserResponseFromCmd), *requestId);
+    }
+
+    if (*messageType == SwitchUserMessageType::LEGACY_ANDROID_SWITCH ||
+        *messageType == SwitchUserMessageType::ANDROID_POST_SWITCH) {
+        ALOGI("request is %s; ignoring it", toString(*messageType).c_str());
+        return nullptr;
+    }
+
+    // Returns default response
+    auto updatedValue = user_hal_helper::toVehiclePropValue(
+            *mValuePool, SwitchUserResponse{
+                                 .requestId = *requestId,
+                                 .messageType = SwitchUserMessageType::VEHICLE_RESPONSE,
+                                 .status = SwitchUserStatus::SUCCESS,
+                         });
+    ALOGI("no lshal response; replying with VEHICLE_RESPONSE / SUCCESS: %s",
+          updatedValue->toString().c_str());
+    return updatedValue;
+}
+
+Result<VehiclePropValuePool::RecyclableType> FakeUserHal::onSetCreateUserResponse(
+        const VehiclePropValue& value) {
+    std::scoped_lock<std::mutex> lockGuard(mLock);
+
+    auto requestId = getRequestId(value);
+    if (!requestId.ok()) {
+        ALOGE("Failed to get requestId on set(CREATE_USER): %s",
+              requestId.error().message().c_str());
+        return requestId.error();
+    }
+
+    if (value.areaId != 0) {
+        ALOGD("set(CREATE_USER) called from lshal; storing it: %s", value.toString().c_str());
+        mCreateUserResponseFromCmd = mValuePool->obtain(value);
+        return nullptr;
+    }
+    ALOGD("set(CREATE_USER) called from Android: %s", value.toString().c_str());
+
+    if (mCreateUserResponseFromCmd != nullptr) {
+        ALOGI("replying CREATE_USER with lshal value:  %s",
+              mCreateUserResponseFromCmd->toString().c_str());
+        return sendUserHalResponse(std::move(mCreateUserResponseFromCmd), *requestId);
+    }
+
+    // Returns default response
+    auto updatedValue = user_hal_helper::toVehiclePropValue(
+            *mValuePool, CreateUserResponse{
+                                 .requestId = *requestId,
+                                 .status = CreateUserStatus::SUCCESS,
+                         });
+    ALOGI("no lshal response; replying with SUCCESS: %s", updatedValue->toString().c_str());
+    return updatedValue;
+}
+
+Result<VehiclePropValuePool::RecyclableType> FakeUserHal::onSetUserIdentificationAssociation(
+        const VehiclePropValue& value) {
+    std::scoped_lock<std::mutex> lockGuard(mLock);
+
+    auto requestId = getRequestId(value);
+    if (!requestId.ok()) {
+        ALOGE("Failed to get requestId on set(USER_IDENTIFICATION_ASSOCIATION): %s",
+              requestId.error().message().c_str());
+        return requestId.error();
+    }
+
+    if (value.areaId != 0) {
+        ALOGD("set(USER_IDENTIFICATION_ASSOCIATION) called from lshal; storing it: %s",
+              value.toString().c_str());
+        mSetUserIdentificationAssociationResponseFromCmd = mValuePool->obtain(value);
+        return nullptr;
+    }
+    ALOGD("set(USER_IDENTIFICATION_ASSOCIATION) called from Android: %s", value.toString().c_str());
+
+    if (mSetUserIdentificationAssociationResponseFromCmd != nullptr) {
+        ALOGI("replying USER_IDENTIFICATION_ASSOCIATION with lshal value:  %s",
+              mSetUserIdentificationAssociationResponseFromCmd->toString().c_str());
+        // Not moving response so it can be used on GET requests
+        auto copy = mValuePool->obtain(*mSetUserIdentificationAssociationResponseFromCmd);
+        return sendUserHalResponse(std::move(copy), *requestId);
+    }
+    // Returns default response
+    return defaultUserIdentificationAssociation(value);
+}
+
+Result<VehiclePropValuePool::RecyclableType> FakeUserHal::defaultUserIdentificationAssociation(
+        const VehiclePropValue& request) {
+    // TODO(b/159498909): return a response with NOT_ASSOCIATED_ANY_USER for all requested types
+    ALOGE("no lshal response for %s; replying with NOT_AVAILABLE", request.toString().c_str());
+    return Error(toInt(StatusCode::NOT_AVAILABLE)) << "not set by lshal";
+}
+
+Result<VehiclePropValuePool::RecyclableType> FakeUserHal::sendUserHalResponse(
+        VehiclePropValuePool::RecyclableType response, int32_t requestId) {
+    switch (response->areaId) {
+        case 1:
+            ALOGD("returning response with right request id");
+            response->value.int32Values[0] = requestId;
+            break;
+        case 2:
+            ALOGD("returning response with wrong request id");
+            response->value.int32Values[0] = -requestId;
+            break;
+        case 3:
+            ALOGD("not generating a property change event because of lshal prop: %s",
+                  response->toString().c_str());
+            return Error(toInt(StatusCode::NOT_AVAILABLE))
+                   << "not generating a property change event because of lshal prop: "
+                   << response->toString();
+        default:
+            ALOGE("invalid action on lshal response: %s", response->toString().c_str());
+            return Error(toInt(StatusCode::INTERNAL_ERROR))
+                   << "invalid action on lshal response: " << response->toString();
+    }
+
+    ALOGD("updating property to: %s", response->toString().c_str());
+    return response;
+}
+
+std::string FakeUserHal::showDumpHelp() const {
+    return fmt::format("{}: dumps state used for user management\n", kUserHalDumpOption);
+}
+
+std::string FakeUserHal::dump(std::string indent) const {
+    std::scoped_lock<std::mutex> lockGuard(mLock);
+
+    std::string info;
+    if (mInitialUserResponseFromCmd != nullptr) {
+        info += fmt::format("{}InitialUserInfo response: {}\n", indent,
+                            mInitialUserResponseFromCmd->toString());
+    } else {
+        info += fmt::format("{}No InitialUserInfo response\n", indent);
+    }
+    if (mSwitchUserResponseFromCmd != nullptr) {
+        info += fmt::format("{}SwitchUser response: {}\n", indent,
+                            mSwitchUserResponseFromCmd->toString());
+    } else {
+        info += fmt::format("{}No SwitchUser response\n", indent);
+    }
+    if (mCreateUserResponseFromCmd != nullptr) {
+        info += fmt::format("{}CreateUser response: {}\n", indent,
+                            mCreateUserResponseFromCmd->toString());
+    } else {
+        info += fmt::format("{}No CreateUser response\n", indent);
+    }
+    if (mSetUserIdentificationAssociationResponseFromCmd != nullptr) {
+        info += fmt::format("{}SetUserIdentificationAssociation response: {}\n", indent,
+                            mSetUserIdentificationAssociationResponseFromCmd->toString());
+    } else {
+        info += fmt::format("{}No SetUserIdentificationAssociation response\n", indent);
+    }
+    return info;
+}
+
+}  // namespace fake
+}  // namespace vehicle
+}  // namespace automotive
+}  // namespace hardware
+}  // namespace android
diff --git a/automotive/vehicle/aidl/impl/fake_impl/userhal/src/UserHalHelper.cpp b/automotive/vehicle/aidl/impl/fake_impl/userhal/src/UserHalHelper.cpp
new file mode 100644
index 0000000..4fd93ae
--- /dev/null
+++ b/automotive/vehicle/aidl/impl/fake_impl/userhal/src/UserHalHelper.cpp
@@ -0,0 +1,403 @@
+/*
+ * Copyright (C) 2021 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.
+ */
+
+#define LOG_TAG "UserHalHelper"
+
+#include "UserHalHelper.h"
+
+#include <VehicleUtils.h>
+#include <log/log.h>
+#include <utils/SystemClock.h>
+
+#include <vector>
+
+namespace android {
+namespace hardware {
+namespace automotive {
+namespace vehicle {
+namespace fake {
+namespace user_hal_helper {
+
+namespace {
+
+using ::aidl::android::hardware::automotive::vehicle::CreateUserRequest;
+using ::aidl::android::hardware::automotive::vehicle::CreateUserResponse;
+using ::aidl::android::hardware::automotive::vehicle::CreateUserStatus;
+using ::aidl::android::hardware::automotive::vehicle::InitialUserInfoRequest;
+using ::aidl::android::hardware::automotive::vehicle::InitialUserInfoRequestType;
+using ::aidl::android::hardware::automotive::vehicle::InitialUserInfoResponse;
+using ::aidl::android::hardware::automotive::vehicle::RemoveUserRequest;
+using ::aidl::android::hardware::automotive::vehicle::SwitchUserMessageType;
+using ::aidl::android::hardware::automotive::vehicle::SwitchUserRequest;
+using ::aidl::android::hardware::automotive::vehicle::SwitchUserResponse;
+using ::aidl::android::hardware::automotive::vehicle::SwitchUserStatus;
+using ::aidl::android::hardware::automotive::vehicle::UserIdentificationAssociationSetValue;
+using ::aidl::android::hardware::automotive::vehicle::UserIdentificationAssociationType;
+using ::aidl::android::hardware::automotive::vehicle::UserIdentificationGetRequest;
+using ::aidl::android::hardware::automotive::vehicle::UserIdentificationResponse;
+using ::aidl::android::hardware::automotive::vehicle::UserIdentificationSetAssociation;
+using ::aidl::android::hardware::automotive::vehicle::UserIdentificationSetRequest;
+using ::aidl::android::hardware::automotive::vehicle::UserInfo;
+using ::aidl::android::hardware::automotive::vehicle::UsersInfo;
+using ::aidl::android::hardware::automotive::vehicle::VehicleProperty;
+using ::aidl::android::hardware::automotive::vehicle::VehiclePropValue;
+using ::android::base::Error;
+using ::android::base::Result;
+
+constexpr const char kSeparator[] = "||";
+constexpr size_t kNumFieldsPerUserInfo = 2;
+constexpr size_t kNumFieldsPerSetAssociation = 2;
+
+Result<void> verifyPropValue(const VehiclePropValue& propValue, VehicleProperty vehicleProperty,
+                             size_t minInt32Values) {
+    auto prop = verifyAndCast<VehicleProperty>(propValue.prop);
+    if (!prop.ok()) {
+        return Error() << "Invalid vehicle property: " << prop.error();
+    }
+    if (*prop != vehicleProperty) {
+        return Error() << "Mismatching " << toString(vehicleProperty) << " request, received "
+                       << toString(*prop) << " property";
+    }
+    if (propValue.value.int32Values.size() < minInt32Values) {
+        return Error() << "Int32Values must have at least " << minInt32Values
+                       << " values, received " << propValue.value.int32Values.size();
+    }
+    return {};
+}
+
+Result<void> parseUserInfo(const std::vector<int32_t>& int32Values, size_t startPos,
+                           UserInfo* userInfo) {
+    if (int32Values.size() < startPos + kNumFieldsPerUserInfo) {
+        return Error() << "Int32Values must have at least " << startPos + 2 << " values, received "
+                       << int32Values.size();
+    }
+    userInfo->userId = int32Values[startPos];
+    int32_t intUserFlags = int32Values[startPos + 1];
+    const int32_t combinedFlags = UserInfo::USER_FLAG_SYSTEM | UserInfo::USER_FLAG_GUEST |
+                                  UserInfo::USER_FLAG_EPHEMERAL | UserInfo::USER_FLAG_ADMIN |
+                                  UserInfo::USER_FLAG_DISABLED | UserInfo::USER_FLAG_PROFILE;
+
+    if ((intUserFlags & ~combinedFlags) != 0) {
+        return Error() << "Invalid user flags: " << intUserFlags << ", must be '|' of UserFlags";
+    }
+    userInfo->flags = intUserFlags;
+    return {};
+}
+
+Result<void> parseUsersInfo(const std::vector<int32_t>& int32Values, size_t startPos,
+                            UsersInfo* usersInfo) {
+    if (int32Values.size() < startPos + 3) {
+        return Error() << "Int32Values must have at least " << startPos + 3 << " values, received "
+                       << int32Values.size();
+    }
+    auto ret = parseUserInfo(int32Values, startPos, &usersInfo->currentUser);
+    if (!ret.ok()) {
+        return ret;
+    }
+    usersInfo->numberUsers = int32Values[startPos + 2];
+    usersInfo->existingUsers.resize(usersInfo->numberUsers);
+    for (size_t i = 0; i < static_cast<size_t>(usersInfo->numberUsers); ++i) {
+        ret = parseUserInfo(int32Values, startPos + 3 + (kNumFieldsPerUserInfo * i),
+                            &usersInfo->existingUsers[i]);
+        if (!ret.ok()) {
+            return Error() << "Failed to parse existing user '" << i << "' info: " << ret.error();
+        }
+    }
+    return {};
+}
+
+Result<void> parseUserAssociationTypes(
+        const std::vector<int32_t>& int32Values, size_t startPos, size_t numberAssociationTypes,
+        std::vector<UserIdentificationAssociationType>* associationTypes) {
+    size_t minInt32Values = startPos + numberAssociationTypes;
+    if (int32Values.size() < minInt32Values) {
+        return Error() << "Int32Values must have at least " << minInt32Values
+                       << " values, received " << int32Values.size();
+    }
+    associationTypes->resize(numberAssociationTypes);
+    for (size_t i = 0; i < static_cast<size_t>(numberAssociationTypes); ++i) {
+        size_t pos = startPos + i;
+        auto type = verifyAndCast<UserIdentificationAssociationType>(int32Values[pos]);
+        if (!type.ok()) {
+            return Error() << "Invalid association type in query '" << i << "': " << type.error();
+        }
+        (*associationTypes)[i] = *type;
+    }
+    return {};
+}
+
+Result<void> parseUserAssociations(const std::vector<int32_t>& int32Values, size_t startPos,
+                                   size_t numberAssociations,
+                                   std::vector<UserIdentificationSetAssociation>* associations) {
+    size_t minInt32Values = startPos + (numberAssociations * kNumFieldsPerSetAssociation);
+    if (int32Values.size() < minInt32Values) {
+        return Error() << "Int32Values must have at least " << minInt32Values
+                       << " values, received " << int32Values.size();
+    }
+    associations->resize(numberAssociations);
+    for (size_t i = 0; i < static_cast<size_t>(numberAssociations); ++i) {
+        size_t pos = startPos + (kNumFieldsPerSetAssociation * i);
+        auto type = verifyAndCast<UserIdentificationAssociationType>(int32Values[pos]);
+        if (!type.ok()) {
+            return Error() << "Invalid association type in request '" << i << "': " << type.error();
+        }
+        (*associations)[i].type = *type;
+        auto value = verifyAndCast<UserIdentificationAssociationSetValue>(int32Values[pos + 1]);
+        if (!value.ok()) {
+            return Error() << "Invalid association set value in request '" << i
+                           << "': " << value.error();
+        }
+        (*associations)[i].value = *value;
+    }
+    return {};
+}
+
+}  // namespace
+
+template <typename T>
+Result<T> verifyAndCast(int32_t value) {
+    T castValue = static_cast<T>(value);
+    for (const auto& v : ::ndk::enum_range<T>()) {
+        if (castValue == v) {
+            return castValue;
+        }
+    }
+
+    return Error() << "Value " << value << " not in enum values";
+}
+
+Result<InitialUserInfoRequest> toInitialUserInfoRequest(const VehiclePropValue& propValue) {
+    auto ret = verifyPropValue(propValue, VehicleProperty::INITIAL_USER_INFO, /*minInt32Values=*/2);
+    if (!ret.ok()) {
+        return ret.error();
+    }
+    InitialUserInfoRequest request;
+    request.requestId = propValue.value.int32Values[0];
+    auto requestType = verifyAndCast<InitialUserInfoRequestType>(propValue.value.int32Values[1]);
+    if (!requestType.ok()) {
+        return Error() << "Invalid InitialUserInfoRequestType: " << requestType.error();
+    }
+    request.requestType = *requestType;
+    ret = parseUsersInfo(propValue.value.int32Values, 2, &request.usersInfo);
+    if (!ret.ok()) {
+        return Error() << "Failed to parse users info: " << ret.error();
+    }
+    return request;
+}
+
+Result<SwitchUserRequest> toSwitchUserRequest(const VehiclePropValue& propValue) {
+    auto ret = verifyPropValue(propValue, VehicleProperty::SWITCH_USER, /*minInt32Values=*/2);
+    if (!ret.ok()) {
+        return ret.error();
+    }
+    SwitchUserRequest request;
+    auto messageType = verifyAndCast<SwitchUserMessageType>(propValue.value.int32Values[1]);
+    if (!messageType.ok()) {
+        return Error() << "Invalid SwitchUserMessageType: " << messageType.error();
+    }
+    if (*messageType != SwitchUserMessageType::LEGACY_ANDROID_SWITCH &&
+        *messageType != SwitchUserMessageType::ANDROID_SWITCH &&
+        *messageType != SwitchUserMessageType::ANDROID_POST_SWITCH) {
+        return Error() << "Invalid " << toString(*messageType)
+                       << " message type from Android System";
+    }
+    request.requestId = propValue.value.int32Values[0];
+    request.messageType = *messageType;
+    ret = parseUserInfo(propValue.value.int32Values, /*startPos=*/2, &request.targetUser);
+    if (!ret.ok()) {
+        return Error() << "Failed to parse target user info: " << ret.error();
+    }
+    ret = parseUsersInfo(propValue.value.int32Values, /*startPos=*/4, &request.usersInfo);
+    if (!ret.ok()) {
+        return Error() << "Failed to parse users info: " << ret.error();
+    }
+    return request;
+}
+
+Result<CreateUserRequest> toCreateUserRequest(const VehiclePropValue& propValue) {
+    auto ret = verifyPropValue(propValue, VehicleProperty::CREATE_USER, /*minInt32Values=*/1);
+    if (!ret.ok()) {
+        return ret.error();
+    }
+    CreateUserRequest request;
+    request.requestId = propValue.value.int32Values[0];
+    ret = parseUserInfo(propValue.value.int32Values, /*startPos=*/1, &request.newUserInfo);
+    if (!ret.ok()) {
+        return Error() << "Failed to parse new user info: " << ret.error();
+    }
+    request.newUserName = propValue.value.stringValue;
+    ret = parseUsersInfo(propValue.value.int32Values, /*startPos=*/3, &request.usersInfo);
+    if (!ret.ok()) {
+        return Error() << "Failed to parse users info: " << ret.error();
+    }
+    return request;
+}
+
+Result<RemoveUserRequest> toRemoveUserRequest(const VehiclePropValue& propValue) {
+    auto ret = verifyPropValue(propValue, VehicleProperty::REMOVE_USER, /*minInt32Values=*/1);
+    if (!ret.ok()) {
+        return ret.error();
+    }
+    RemoveUserRequest request;
+    request.requestId = propValue.value.int32Values[0];
+    ret = parseUserInfo(propValue.value.int32Values, /*startPos=*/1, &request.removedUserInfo);
+    if (!ret.ok()) {
+        return Error() << "Failed to parse removed user info: " << ret.error();
+    }
+    ret = parseUsersInfo(propValue.value.int32Values, /*startPos=*/3, &request.usersInfo);
+    if (!ret.ok()) {
+        return Error() << "Failed to parse users info: " << ret.error();
+    }
+    return request;
+}
+
+Result<UserIdentificationGetRequest> toUserIdentificationGetRequest(
+        const VehiclePropValue& propValue) {
+    auto ret = verifyPropValue(propValue, VehicleProperty::USER_IDENTIFICATION_ASSOCIATION,
+                               /*minInt32Values=*/4);
+    if (!ret.ok()) {
+        return ret.error();
+    }
+    UserIdentificationGetRequest request;
+    request.requestId = propValue.value.int32Values[0];
+    ret = parseUserInfo(propValue.value.int32Values, /*startPos=*/1, &request.userInfo);
+    if (!ret.ok()) {
+        return Error() << "Failed to parse user info: " << ret.error();
+    }
+    request.numberAssociationTypes = propValue.value.int32Values[3];
+    ret = parseUserAssociationTypes(propValue.value.int32Values, 4, request.numberAssociationTypes,
+                                    &request.associationTypes);
+    if (!ret.ok()) {
+        return Error() << "Failed to parse UserIdentificationAssociationType: " << ret.error();
+    }
+    return request;
+}
+
+Result<UserIdentificationSetRequest> toUserIdentificationSetRequest(
+        const VehiclePropValue& propValue) {
+    auto ret = verifyPropValue(propValue, VehicleProperty::USER_IDENTIFICATION_ASSOCIATION,
+                               /*minInt32Values=*/4);
+    if (!ret.ok()) {
+        return ret.error();
+    }
+    UserIdentificationSetRequest request;
+    request.requestId = propValue.value.int32Values[0];
+    ret = parseUserInfo(propValue.value.int32Values, /*startPos=*/1, &request.userInfo);
+    if (!ret.ok()) {
+        return Error() << "Failed to parse user info: " << ret.error();
+    }
+    request.numberAssociations = propValue.value.int32Values[3];
+    ret = parseUserAssociations(propValue.value.int32Values, 4, request.numberAssociations,
+                                &request.associations);
+    if (!ret.ok()) {
+        return Error() << "Failed to parse UserIdentificationSetAssociation: " << ret.error();
+    }
+    return request;
+}
+
+Result<VehiclePropValuePool::RecyclableType> toVehiclePropValue(VehiclePropValuePool& pool,
+                                                                const SwitchUserRequest& request) {
+    if (request.messageType != SwitchUserMessageType::VEHICLE_REQUEST) {
+        return Errorf("Invalid %s message type %s from HAL",
+                      toString(VehicleProperty::SWITCH_USER).c_str(),
+                      toString(request.messageType).c_str());
+    }
+    int32_t switchUserProp = toInt(VehicleProperty::SWITCH_USER);
+    auto propValue = pool.obtain(getPropType(switchUserProp));
+    propValue->prop = switchUserProp;
+    propValue->timestamp = elapsedRealtimeNano();
+    propValue->value.int32Values.resize(3);
+    propValue->value.int32Values[0] = static_cast<int32_t>(request.requestId);
+    propValue->value.int32Values[1] = static_cast<int32_t>(request.messageType);
+    propValue->value.int32Values[2] = static_cast<int32_t>(request.targetUser.userId);
+    return propValue;
+}
+
+VehiclePropValuePool::RecyclableType toVehiclePropValue(VehiclePropValuePool& pool,
+                                                        const InitialUserInfoResponse& response) {
+    int32_t initialUserInfoProp = toInt(VehicleProperty::INITIAL_USER_INFO);
+    auto propValue = pool.obtain(getPropType(initialUserInfoProp));
+    propValue->prop = initialUserInfoProp;
+    propValue->timestamp = elapsedRealtimeNano();
+    propValue->value.int32Values.resize(4);
+    propValue->value.int32Values[0] = static_cast<int32_t>(response.requestId);
+    propValue->value.int32Values[1] = static_cast<int32_t>(response.action);
+    propValue->value.int32Values[2] = static_cast<int32_t>(response.userToSwitchOrCreate.userId);
+    propValue->value.int32Values[3] = response.userToSwitchOrCreate.flags;
+    propValue->value.stringValue = std::string(response.userLocales) + std::string(kSeparator) +
+                                   std::string(response.userNameToCreate);
+    return propValue;
+}
+
+VehiclePropValuePool::RecyclableType toVehiclePropValue(VehiclePropValuePool& pool,
+                                                        const SwitchUserResponse& response) {
+    int32_t switchUserProp = toInt(VehicleProperty::SWITCH_USER);
+    auto propValue = pool.obtain(getPropType(switchUserProp));
+    propValue->prop = switchUserProp;
+    propValue->timestamp = elapsedRealtimeNano();
+    propValue->value.int32Values.resize(3);
+    propValue->value.int32Values[0] = static_cast<int32_t>(response.requestId);
+    propValue->value.int32Values[1] = static_cast<int32_t>(response.messageType);
+    propValue->value.int32Values[2] = static_cast<int32_t>(response.status);
+    if (response.status == SwitchUserStatus::FAILURE) {
+        propValue->value.stringValue = response.errorMessage;
+    }
+    return propValue;
+}
+
+VehiclePropValuePool::RecyclableType toVehiclePropValue(VehiclePropValuePool& pool,
+                                                        const CreateUserResponse& response) {
+    int32_t createUserProp = toInt(VehicleProperty::CREATE_USER);
+    auto propValue = pool.obtain(getPropType(createUserProp));
+    propValue->prop = createUserProp;
+    propValue->timestamp = elapsedRealtimeNano();
+    propValue->value.int32Values.resize(2);
+    propValue->value.int32Values[0] = static_cast<int32_t>(response.requestId);
+    propValue->value.int32Values[1] = static_cast<int32_t>(response.status);
+    if (response.status == CreateUserStatus::FAILURE) {
+        propValue->value.stringValue = response.errorMessage;
+    }
+    return propValue;
+}
+
+VehiclePropValuePool::RecyclableType toVehiclePropValue(
+        VehiclePropValuePool& pool, const UserIdentificationResponse& response) {
+    int32_t userIdAssocProp = toInt(VehicleProperty::USER_IDENTIFICATION_ASSOCIATION);
+    auto propValue = pool.obtain(getPropType(userIdAssocProp));
+    propValue->prop = userIdAssocProp;
+    propValue->timestamp = elapsedRealtimeNano();
+    propValue->value.int32Values.resize(2 + (response.numberAssociation * 2));
+    propValue->value.int32Values[0] = static_cast<int32_t>(response.requestId);
+    propValue->value.int32Values[1] = static_cast<int32_t>(response.numberAssociation);
+    for (size_t i = 0; i < static_cast<size_t>(response.numberAssociation); ++i) {
+        size_t int32ValuesPos = 2 + (2 * i);
+        propValue->value.int32Values[int32ValuesPos] =
+                static_cast<int32_t>(response.associations[i].type);
+        propValue->value.int32Values[int32ValuesPos + 1] =
+                static_cast<int32_t>(response.associations[i].value);
+    }
+    if (!response.errorMessage.empty()) {
+        propValue->value.stringValue = response.errorMessage;
+    }
+    return propValue;
+}
+
+}  // namespace user_hal_helper
+}  // namespace fake
+}  // namespace vehicle
+}  // namespace automotive
+}  // namespace hardware
+}  // namespace android
diff --git a/automotive/vehicle/aidl/impl/fake_impl/userhal/test/Android.bp b/automotive/vehicle/aidl/impl/fake_impl/userhal/test/Android.bp
new file mode 100644
index 0000000..7d0a534
--- /dev/null
+++ b/automotive/vehicle/aidl/impl/fake_impl/userhal/test/Android.bp
@@ -0,0 +1,33 @@
+/*
+ * Copyright (C) 2021 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.
+ */
+
+package {
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
+cc_test {
+    name: "FakeUserHalTest",
+    vendor: true,
+    srcs: ["*.cpp"],
+    defaults: ["VehicleHalDefaults"],
+    static_libs: [
+        "FakeUserHal",
+        "VehicleHalUtils",
+        "libgtest",
+        "libgmock",
+    ],
+    test_suites: ["device-tests"],
+}
diff --git a/automotive/vehicle/aidl/impl/fake_impl/userhal/test/UserHalHelper_test.cpp b/automotive/vehicle/aidl/impl/fake_impl/userhal/test/UserHalHelper_test.cpp
new file mode 100644
index 0000000..2afb2e3
--- /dev/null
+++ b/automotive/vehicle/aidl/impl/fake_impl/userhal/test/UserHalHelper_test.cpp
@@ -0,0 +1,715 @@
+/*
+ * Copyright (C) 2021 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 "UserHalHelper.h"
+
+#include <VehicleUtils.h>
+#include <aidl/android/hardware/automotive/vehicle/InitialUserInfoResponseAction.h>
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+
+#include <cstdint>
+
+namespace android {
+namespace hardware {
+namespace automotive {
+namespace vehicle {
+namespace fake {
+namespace user_hal_helper {
+
+namespace {
+
+using ::testing::Eq;
+using ::testing::Gt;
+using ::testing::IsNull;
+using ::testing::NotNull;
+using ::testing::Pointee;
+
+using ::aidl::android::hardware::automotive::vehicle::CreateUserRequest;
+using ::aidl::android::hardware::automotive::vehicle::CreateUserResponse;
+using ::aidl::android::hardware::automotive::vehicle::CreateUserStatus;
+using ::aidl::android::hardware::automotive::vehicle::InitialUserInfoRequest;
+using ::aidl::android::hardware::automotive::vehicle::InitialUserInfoRequestType;
+using ::aidl::android::hardware::automotive::vehicle::InitialUserInfoResponse;
+using ::aidl::android::hardware::automotive::vehicle::InitialUserInfoResponseAction;
+using ::aidl::android::hardware::automotive::vehicle::RemoveUserRequest;
+using ::aidl::android::hardware::automotive::vehicle::SwitchUserMessageType;
+using ::aidl::android::hardware::automotive::vehicle::SwitchUserRequest;
+using ::aidl::android::hardware::automotive::vehicle::SwitchUserResponse;
+using ::aidl::android::hardware::automotive::vehicle::SwitchUserStatus;
+using ::aidl::android::hardware::automotive::vehicle::UserIdentificationAssociationSetValue;
+using ::aidl::android::hardware::automotive::vehicle::UserIdentificationAssociationType;
+using ::aidl::android::hardware::automotive::vehicle::UserIdentificationAssociationValue;
+using ::aidl::android::hardware::automotive::vehicle::UserIdentificationGetRequest;
+using ::aidl::android::hardware::automotive::vehicle::UserIdentificationResponse;
+using ::aidl::android::hardware::automotive::vehicle::UserIdentificationSetRequest;
+using ::aidl::android::hardware::automotive::vehicle::UserInfo;
+using ::aidl::android::hardware::automotive::vehicle::VehicleProperty;
+using ::aidl::android::hardware::automotive::vehicle::VehiclePropValue;
+
+constexpr int32_t INITIAL_USER_INFO = toInt(VehicleProperty::INITIAL_USER_INFO);
+constexpr int32_t SWITCH_USER = toInt(VehicleProperty::SWITCH_USER);
+constexpr int32_t CREATE_USER = toInt(VehicleProperty::CREATE_USER);
+constexpr int32_t REMOVE_USER = toInt(VehicleProperty::REMOVE_USER);
+constexpr int32_t USER_IDENTIFICATION_ASSOCIATION =
+        toInt(VehicleProperty::USER_IDENTIFICATION_ASSOCIATION);
+
+constexpr int32_t FIRST_BOOT_AFTER_OTA = toInt(InitialUserInfoRequestType::FIRST_BOOT_AFTER_OTA);
+constexpr int32_t LEGACY_ANDROID_SWITCH = toInt(SwitchUserMessageType::LEGACY_ANDROID_SWITCH);
+constexpr int32_t VEHICLE_REQUEST = toInt(SwitchUserMessageType::VEHICLE_REQUEST);
+
+constexpr int32_t NONE_USER = 0;
+constexpr int32_t GUEST_USER = toInt(UserInfo::USER_FLAG_GUEST);
+constexpr int32_t SYSTEM_USER = toInt(UserInfo::USER_FLAG_SYSTEM);
+constexpr int32_t SYSTEM_ADMIN_USER = SYSTEM_USER | toInt(UserInfo::USER_FLAG_ADMIN);
+// 0x1111 is not a valid UserFlags combination.
+constexpr int32_t INVALID_USER_FLAG = 0x1111;
+
+constexpr int32_t USER_ID_ASSOC_KEY_FOB = toInt(UserIdentificationAssociationType::KEY_FOB);
+constexpr int32_t USER_ID_ASSOC_CUSTOM_1 = toInt(UserIdentificationAssociationType::CUSTOM_1);
+
+constexpr int32_t USER_ID_ASSOC_SET_CURRENT_USER =
+        toInt(UserIdentificationAssociationSetValue::ASSOCIATE_CURRENT_USER);
+constexpr int32_t USER_ID_ASSOC_UNSET_CURRENT_USER =
+        toInt(UserIdentificationAssociationSetValue::DISASSOCIATE_CURRENT_USER);
+
+constexpr int32_t USER_ID_ASSOC_CURRENT_USER =
+        toInt(UserIdentificationAssociationValue::ASSOCIATED_CURRENT_USER);
+constexpr int32_t USER_ID_ASSOC_NO_USER =
+        toInt(UserIdentificationAssociationValue::NOT_ASSOCIATED_ANY_USER);
+
+}  // namespace
+
+TEST(UserHalHelperTest, TestToInitialUserInfoRequest) {
+    VehiclePropValue propValue{
+            .prop = INITIAL_USER_INFO,
+            .value = {.int32Values = {23, FIRST_BOOT_AFTER_OTA, 10, NONE_USER, 2, 0, SYSTEM_USER,
+                                      10, NONE_USER}},
+    };
+    InitialUserInfoRequest expected{
+            .requestId = 23,
+            .requestType = InitialUserInfoRequestType::FIRST_BOOT_AFTER_OTA,
+            .usersInfo = {{10, 0}, 2, {{0, SYSTEM_USER}, {10, 0}}},
+    };
+
+    auto actual = toInitialUserInfoRequest(propValue);
+
+    ASSERT_TRUE(actual.ok()) << actual.error().message();
+    EXPECT_THAT(actual.value(), Eq(expected));
+}
+
+TEST(UserHalHelperTest, TestToInitialUserInfoRequestUserFlagsBitCombination) {
+    // SYSTEM_ADMIN_USER is two UserFlags combined.
+    VehiclePropValue propValue{
+            .prop = INITIAL_USER_INFO,
+            .value = {.int32Values = {23, FIRST_BOOT_AFTER_OTA, 10, NONE_USER, 2, 0,
+                                      SYSTEM_ADMIN_USER, 10, NONE_USER}},
+    };
+    InitialUserInfoRequest expected{
+            .requestId = 23,
+            .requestType = InitialUserInfoRequestType::FIRST_BOOT_AFTER_OTA,
+            .usersInfo = {{10, 0}, 2, {{0, SYSTEM_ADMIN_USER}, {10, 0}}},
+    };
+
+    auto actual = toInitialUserInfoRequest(propValue);
+
+    ASSERT_TRUE(actual.ok()) << actual.error().message();
+    EXPECT_THAT(actual.value(), Eq(expected));
+}
+
+TEST(UserHalHelperTest, TestToInitialUserInfoRequestUserInvalidUserFlag) {
+    VehiclePropValue propValue{
+            .prop = INITIAL_USER_INFO,
+            .value = {.int32Values = {23, FIRST_BOOT_AFTER_OTA, 10, NONE_USER, 2, 0,
+                                      INVALID_USER_FLAG, 10, NONE_USER}},
+    };
+
+    auto actual = toInitialUserInfoRequest(propValue);
+
+    EXPECT_FALSE(actual.ok()) << "No error returned on invalid user flags";
+}
+
+TEST(UserHalHelperTest, TestFailsToInitialUserInfoRequestWithMismatchingPropType) {
+    VehiclePropValue propValue{
+            .prop = INT32_MAX,
+            .value = {.int32Values = {23, FIRST_BOOT_AFTER_OTA, 10, NONE_USER, 2, 0, SYSTEM_USER,
+                                      10, NONE_USER}},
+    };
+
+    auto actual = toInitialUserInfoRequest(propValue);
+
+    EXPECT_FALSE(actual.ok()) << "No error returned on mismatching property type";
+}
+
+TEST(UserHalHelperTest, TestFailsToInitialUserInfoRequestWithInvalidRequestType) {
+    VehiclePropValue propValue{
+            .prop = INITIAL_USER_INFO,
+            .value = {.int32Values = {23, INT32_MAX, 10, NONE_USER, 2, 0, SYSTEM_USER, 10,
+                                      NONE_USER}},
+    };
+
+    auto actual = toInitialUserInfoRequest(propValue);
+
+    EXPECT_FALSE(actual.ok()) << "No error returned on invalid request type";
+}
+
+TEST(UserHalHelperTest, TestFailsToInitialUserInfoRequestWithInvalidUserFlag) {
+    VehiclePropValue propValue{
+            .prop = INITIAL_USER_INFO,
+            .value = {.int32Values = {23, FIRST_BOOT_AFTER_OTA, 10, NONE_USER, 2, 0, SYSTEM_USER,
+                                      10, INT32_MAX}},
+    };
+
+    auto actual = toInitialUserInfoRequest(propValue);
+
+    EXPECT_FALSE(actual.ok()) << "No error returned on invalid user flags";
+}
+
+TEST(UserHalHelperTest, TestFailsToInitialUserInfoRequestWithIncompleteUsersInfo) {
+    VehiclePropValue propValueMissingSecondUserInfo{
+            .prop = INITIAL_USER_INFO,
+            .value = {.int32Values = {23, FIRST_BOOT_AFTER_OTA, 10, NONE_USER, 2, 0,
+                                      SYSTEM_USER /*Missing 2nd UserInfo*/}},
+    };
+
+    auto actual = toInitialUserInfoRequest(propValueMissingSecondUserInfo);
+
+    EXPECT_FALSE(actual.ok()) << "No error returned on missing second user info";
+
+    VehiclePropValue propValueMissingUsersInfo{
+            .prop = INITIAL_USER_INFO,
+            .value = {.int32Values = {23, FIRST_BOOT_AFTER_OTA, /*Missing UsersInfo*/}},
+    };
+
+    actual = toInitialUserInfoRequest(propValueMissingUsersInfo);
+
+    EXPECT_FALSE(actual.ok()) << "No error returned on missing users info";
+}
+
+TEST(UserHalHelperTest, TestToSwitchUserRequest) {
+    VehiclePropValue propValue{
+            .prop = SWITCH_USER,
+            .value = {.int32Values = {23, LEGACY_ANDROID_SWITCH, 0, SYSTEM_USER, 10, NONE_USER, 2,
+                                      0, SYSTEM_USER, 10, NONE_USER}},
+    };
+    SwitchUserRequest expected{
+            .requestId = 23,
+            .messageType = SwitchUserMessageType::LEGACY_ANDROID_SWITCH,
+            .targetUser = {0, SYSTEM_USER},
+            .usersInfo = {{10, 0}, 2, {{0, SYSTEM_USER}, {10, 0}}},
+    };
+
+    auto actual = toSwitchUserRequest(propValue);
+
+    ASSERT_TRUE(actual.ok()) << actual.error().message();
+    EXPECT_THAT(actual.value(), Eq(expected));
+}
+
+TEST(UserHalHelperTest, TestFailsToSwitchUserRequestWithMismatchingPropType) {
+    VehiclePropValue propValue{
+            .prop = INITIAL_USER_INFO,
+            .value = {.int32Values = {23, LEGACY_ANDROID_SWITCH, 0, SYSTEM_USER, 10, NONE_USER, 2,
+                                      0, SYSTEM_USER, 10, NONE_USER}},
+    };
+
+    auto actual = toSwitchUserRequest(propValue);
+
+    EXPECT_FALSE(actual.ok()) << "No error returned on mismatching property type";
+}
+
+TEST(UserHalHelperTest, TestFailsToSwitchUserRequestWithInvalidMessageType) {
+    VehiclePropValue propValueIncompatibleMessageType{
+            .prop = SWITCH_USER,
+            .value = {.int32Values = {23, VEHICLE_REQUEST, 0, SYSTEM_USER, 10, NONE_USER, 2, 0,
+                                      SYSTEM_USER, 10, NONE_USER}},
+    };
+
+    auto actual = toSwitchUserRequest(propValueIncompatibleMessageType);
+
+    EXPECT_FALSE(actual.ok()) << "No error returned on incompatible message type";
+
+    VehiclePropValue propValueInvalidMessageType{
+            .prop = SWITCH_USER,
+            .value = {.int32Values = {23, INT32_MAX, 0, SYSTEM_USER, 10, NONE_USER, 2, 0,
+                                      SYSTEM_USER, 10, NONE_USER}},
+    };
+
+    actual = toSwitchUserRequest(propValueInvalidMessageType);
+
+    EXPECT_FALSE(actual.ok()) << "No error returned on invalid message type";
+}
+
+TEST(UserHalHelperTest, TestFailsToSwitchUserRequestWithIncompleteUsersInfo) {
+    VehiclePropValue propValueMissingSecondUserInfo{
+            .prop = SWITCH_USER,
+            .value = {.int32Values = {23, LEGACY_ANDROID_SWITCH, 0, SYSTEM_USER, 10, NONE_USER, 2,
+                                      0, SYSTEM_USER,
+                                      /*Missing 2nd UserInfo*/}},
+    };
+
+    auto actual = toSwitchUserRequest(propValueMissingSecondUserInfo);
+
+    EXPECT_FALSE(actual.ok()) << "No error returned on missing second user info";
+
+    VehiclePropValue propValueMissingUsersInfo{
+            .prop = SWITCH_USER,
+            .value = {.int32Values = {23, LEGACY_ANDROID_SWITCH, 0, SYSTEM_USER,
+                                      /*Missing UsersInfo*/}},
+    };
+
+    actual = toSwitchUserRequest(propValueMissingUsersInfo);
+
+    EXPECT_FALSE(actual.ok()) << "No error returned on missing users info";
+
+    VehiclePropValue propValueMissingTargetUser{
+            .prop = SWITCH_USER,
+            .value = {.int32Values = {23, LEGACY_ANDROID_SWITCH, /*Missing target UserInfo*/}},
+    };
+
+    actual = toSwitchUserRequest(propValueMissingTargetUser);
+
+    EXPECT_FALSE(actual.ok()) << "No error returned on missing target user info";
+}
+
+TEST(UserHalHelperTest, TestToCreateUserRequest) {
+    VehiclePropValue propValue{
+            .prop = CREATE_USER,
+            .value = {.int32Values = {23, 11, GUEST_USER, 10, NONE_USER, 2, 0, SYSTEM_USER, 10,
+                                      NONE_USER},
+                      .stringValue = "Guest11"},
+    };
+    CreateUserRequest expected{
+            .requestId = 23,
+            .newUserInfo = {11, GUEST_USER},
+            .newUserName = "Guest11",
+            .usersInfo = {{10, 0}, 2, {{0, SYSTEM_USER}, {10, 0}}},
+    };
+
+    auto actual = toCreateUserRequest(propValue);
+
+    ASSERT_TRUE(actual.ok()) << actual.error().message();
+    EXPECT_THAT(actual.value(), Eq(expected));
+}
+
+TEST(UserHalHelperTest, TestFailsToCreateUserRequestWithMismatchingPropType) {
+    VehiclePropValue propValue{
+            .prop = INITIAL_USER_INFO,
+            .value = {.int32Values = {23, 11, GUEST_USER, 10, NONE_USER, 2, 0, SYSTEM_USER, 10,
+                                      NONE_USER},
+                      .stringValue = "Guest11"},
+    };
+
+    auto actual = toCreateUserRequest(propValue);
+
+    EXPECT_FALSE(actual.ok()) << "No error returned on mismatching property type";
+}
+
+TEST(UserHalHelperTest, TestFailsToCreateUserRequestWithIncompleteUsersInfo) {
+    VehiclePropValue propValueMissingSecondUserInfo{
+            .prop = CREATE_USER,
+            .value = {.int32Values = {23, 11, GUEST_USER, 10, NONE_USER, 2, 0,
+                                      SYSTEM_USER /*Missing 2nd UserInfo*/},
+                      .stringValue = "Guest11"},
+    };
+
+    auto actual = toCreateUserRequest(propValueMissingSecondUserInfo);
+
+    EXPECT_FALSE(actual.ok()) << "No error returned on missing second user info";
+
+    VehiclePropValue propValueMissingUsersInfo{
+            .prop = CREATE_USER,
+            .value = {.int32Values = {23, 11, GUEST_USER, /*Missing UsersInfo*/},
+                      .stringValue = "Guest11"},
+    };
+
+    actual = toCreateUserRequest(propValueMissingUsersInfo);
+
+    EXPECT_FALSE(actual.ok()) << "No error returned on missing users info";
+
+    VehiclePropValue propValueMissingCreateUserInfo{
+            .prop = CREATE_USER,
+            .value = {.int32Values = {23, /*Missing create UserInfo*/}, .stringValue = "Guest11"},
+    };
+
+    actual = toCreateUserRequest(propValueMissingCreateUserInfo);
+
+    EXPECT_FALSE(actual.ok()) << "No error returned on missing create user info";
+}
+
+TEST(UserHalHelperTest, TestToRemoveUserRequest) {
+    VehiclePropValue propValue{
+            .prop = REMOVE_USER,
+            .value = {.int32Values = {23, 10, NONE_USER, 10, NONE_USER, 2, 0, SYSTEM_USER, 10,
+                                      NONE_USER}},
+    };
+    RemoveUserRequest expected{
+            .requestId = 23,
+            .removedUserInfo = {10, 0},
+            .usersInfo = {{10, 0}, 2, {{0, SYSTEM_USER}, {10, 0}}},
+    };
+
+    auto actual = toRemoveUserRequest(propValue);
+
+    ASSERT_TRUE(actual.ok()) << actual.error().message();
+    EXPECT_THAT(actual.value(), Eq(expected));
+}
+
+TEST(UserHalHelperTest, TestFailsToRemoveUserRequestWithMismatchingPropType) {
+    VehiclePropValue propValue{
+            .prop = INITIAL_USER_INFO,
+            .value = {.int32Values = {23, 10, NONE_USER, 10, NONE_USER, 2, 0, SYSTEM_USER, 10,
+                                      NONE_USER}},
+    };
+
+    auto actual = toRemoveUserRequest(propValue);
+
+    EXPECT_FALSE(actual.ok()) << "No error returned on mismatching property type";
+}
+
+TEST(UserHalHelperTest, TestFailsToRemoveUserRequestWithIncompleteUsersInfo) {
+    VehiclePropValue propValueMissingSecondUserInfo{
+            .prop = REMOVE_USER,
+            .value = {.int32Values = {23, 10, NONE_USER, 10, NONE_USER, 2, 0,
+                                      SYSTEM_USER /*Missing 2nd UserInfo*/}},
+    };
+
+    auto actual = toRemoveUserRequest(propValueMissingSecondUserInfo);
+
+    EXPECT_FALSE(actual.ok()) << "No error returned on missing second user info";
+
+    VehiclePropValue propValueMissingUsersInfo{
+            .prop = REMOVE_USER,
+            .value = {.int32Values = {23, 10, NONE_USER, /*Missing UsersInfo*/}},
+    };
+
+    actual = toRemoveUserRequest(propValueMissingUsersInfo);
+
+    EXPECT_FALSE(actual.ok()) << "No error returned on missing users info";
+
+    VehiclePropValue propValueMissingRemoveUserInfo{
+            .prop = REMOVE_USER,
+            .value = {.int32Values = {23, /*Missing remove UserInfo*/}},
+    };
+
+    actual = toRemoveUserRequest(propValueMissingRemoveUserInfo);
+
+    EXPECT_FALSE(actual.ok()) << "No error returned on missing remove user info";
+}
+
+TEST(UserHalHelperTest, TestFailsToUserIdentificationGetRequest) {
+    VehiclePropValue propValue{
+            .prop = USER_IDENTIFICATION_ASSOCIATION,
+            .value = {.int32Values = {23, 10, NONE_USER, 2, USER_ID_ASSOC_KEY_FOB,
+                                      USER_ID_ASSOC_CUSTOM_1}},
+    };
+    UserIdentificationGetRequest expected{
+            .requestId = 23,
+            .userInfo = {10, 0},
+            .numberAssociationTypes = 2,
+            .associationTypes = {UserIdentificationAssociationType::KEY_FOB,
+                                 UserIdentificationAssociationType::CUSTOM_1},
+    };
+
+    auto actual = toUserIdentificationGetRequest(propValue);
+
+    ASSERT_TRUE(actual.ok()) << actual.error().message();
+    EXPECT_THAT(actual.value(), Eq(expected));
+}
+
+TEST(UserHalHelperTest, TestFailsToUserIdentificationGetRequestWithMismatchingPropType) {
+    VehiclePropValue propValue{
+            .prop = INITIAL_USER_INFO,
+            .value = {.int32Values = {23, 10, NONE_USER, 2, USER_ID_ASSOC_KEY_FOB,
+                                      USER_ID_ASSOC_CUSTOM_1}},
+    };
+
+    auto actual = toUserIdentificationGetRequest(propValue);
+
+    EXPECT_FALSE(actual.ok()) << "No error returned on mismatching property type";
+}
+
+TEST(UserHalHelperTest, TestFailsToUserIdentificationGetRequestWithInvalidAssociationTypes) {
+    VehiclePropValue propValue{
+            .prop = USER_IDENTIFICATION_ASSOCIATION,
+            .value = {.int32Values = {23, 10, NONE_USER, 1, INT32_MAX}},
+    };
+
+    auto actual = toUserIdentificationGetRequest(propValue);
+
+    EXPECT_FALSE(actual.ok()) << "No error returned on invalid association type";
+}
+
+TEST(UserHalHelperTest, TestFailsToUserIdentificationGetRequestWithIncompleteAssociationTypes) {
+    VehiclePropValue propValueMissingSecondAssociationType{
+            .prop = USER_IDENTIFICATION_ASSOCIATION,
+            .value = {.int32Values = {23, 10, NONE_USER, 2,
+                                      USER_ID_ASSOC_KEY_FOB /*Missing 2nd association type*/}},
+    };
+
+    auto actual = toUserIdentificationGetRequest(propValueMissingSecondAssociationType);
+
+    EXPECT_FALSE(actual.ok()) << "No error returned on missing second association type";
+
+    VehiclePropValue propValueMissingNumberAssociationTypes{
+            .prop = USER_IDENTIFICATION_ASSOCIATION,
+            .value = {.int32Values = {23, 10, NONE_USER, /*Missing number association types*/}},
+    };
+
+    actual = toUserIdentificationGetRequest(propValueMissingNumberAssociationTypes);
+
+    EXPECT_FALSE(actual.ok()) << "No error returned on missing number association types";
+}
+
+TEST(UserHalHelperTest, TestFailsToUserIdentificationGetRequestWithMissingUserInfo) {
+    VehiclePropValue propValue{
+            .prop = USER_IDENTIFICATION_ASSOCIATION,
+            .value = {.int32Values = {23, /*Missing user info*/}},
+    };
+
+    auto actual = toUserIdentificationGetRequest(propValue);
+
+    EXPECT_FALSE(actual.ok()) << "No error returned on missing UserInfo";
+}
+
+TEST(UserHalHelperTest, TestToUserIdentificationSetRequest) {
+    VehiclePropValue propValue{
+            .prop = USER_IDENTIFICATION_ASSOCIATION,
+            .value = {.int32Values = {23, 10, NONE_USER, 2, USER_ID_ASSOC_KEY_FOB,
+                                      USER_ID_ASSOC_SET_CURRENT_USER, USER_ID_ASSOC_CUSTOM_1,
+                                      USER_ID_ASSOC_UNSET_CURRENT_USER}},
+    };
+    UserIdentificationSetRequest expected{
+            .requestId = 23,
+            .userInfo = {10, 0},
+            .numberAssociations = 2,
+            .associations = {{UserIdentificationAssociationType::KEY_FOB,
+                              UserIdentificationAssociationSetValue::ASSOCIATE_CURRENT_USER},
+                             {UserIdentificationAssociationType::CUSTOM_1,
+                              UserIdentificationAssociationSetValue::DISASSOCIATE_CURRENT_USER}},
+    };
+
+    auto actual = toUserIdentificationSetRequest(propValue);
+
+    ASSERT_TRUE(actual.ok()) << actual.error().message();
+    EXPECT_THAT(actual.value(), Eq(expected));
+}
+
+TEST(UserHalHelperTest, TestFailsToUserIdentificationSetRequestWithMismatchingPropType) {
+    VehiclePropValue propValue{
+            .prop = INITIAL_USER_INFO,
+            .value = {.int32Values = {23, 10, NONE_USER, 2, USER_ID_ASSOC_KEY_FOB,
+                                      USER_ID_ASSOC_SET_CURRENT_USER, USER_ID_ASSOC_CUSTOM_1,
+                                      USER_ID_ASSOC_UNSET_CURRENT_USER}},
+    };
+
+    auto actual = toUserIdentificationSetRequest(propValue);
+
+    EXPECT_FALSE(actual.ok()) << "No error returned on mismatching property type";
+}
+
+TEST(UserHalHelperTest, TestFailsToUserIdentificationSetRequestWithInvalidAssociations) {
+    VehiclePropValue propValueInvalidAssociationType{
+            .prop = USER_IDENTIFICATION_ASSOCIATION,
+            .value = {.int32Values = {23, 10, NONE_USER, 1, INT32_MAX,
+                                      USER_ID_ASSOC_SET_CURRENT_USER}},
+    };
+
+    auto actual = toUserIdentificationSetRequest(propValueInvalidAssociationType);
+
+    EXPECT_FALSE(actual.ok()) << "No error returned on invalid association type";
+
+    VehiclePropValue propValueInvalidAssociationValue{
+            .prop = USER_IDENTIFICATION_ASSOCIATION,
+            .value = {.int32Values = {23, 10, NONE_USER, USER_ID_ASSOC_KEY_FOB, INT32_MAX}},
+    };
+
+    actual = toUserIdentificationSetRequest(propValueInvalidAssociationValue);
+
+    EXPECT_FALSE(actual.ok()) << "No error returned on missing number association types";
+}
+
+TEST(UserHalHelperTest, TestFailsToUserIdentificationSetRequestWithIncompleteAssociations) {
+    VehiclePropValue propValueMissingSecondAssociationType{
+            .prop = USER_IDENTIFICATION_ASSOCIATION,
+            .value = {.int32Values = {23, 10, NONE_USER, 2, USER_ID_ASSOC_KEY_FOB,
+                                      USER_ID_ASSOC_SET_CURRENT_USER,
+                                      /*Missing 2nd association*/}},
+    };
+
+    auto actual = toUserIdentificationSetRequest(propValueMissingSecondAssociationType);
+
+    EXPECT_FALSE(actual.ok()) << "No error returned on missing second association type";
+
+    VehiclePropValue propValueMissingNumberAssociationTypes{
+            .prop = USER_IDENTIFICATION_ASSOCIATION,
+            .value = {.int32Values = {23, 10, NONE_USER, /*Missing number associations*/}},
+    };
+
+    actual = toUserIdentificationSetRequest(propValueMissingNumberAssociationTypes);
+
+    EXPECT_FALSE(actual.ok()) << "No error returned on missing number association types";
+}
+
+TEST(UserHalHelperTest, TestFailsToUserIdentificationSetRequestWithMissingUserInfo) {
+    VehiclePropValue propValue{
+            .prop = USER_IDENTIFICATION_ASSOCIATION,
+            .value = {.int32Values = {23, /*Missing user info*/}},
+    };
+
+    auto actual = toUserIdentificationSetRequest(propValue);
+
+    EXPECT_FALSE(actual.ok()) << "No error returned on missing UserInfo";
+}
+
+TEST(UserHalHelperTest, TestSwitchUserRequestToVehiclePropValue) {
+    SwitchUserRequest request{
+            .requestId = 23,
+            .messageType = SwitchUserMessageType::VEHICLE_REQUEST,
+            .targetUser = {11, GUEST_USER},
+    };
+    VehiclePropValue expected{
+            .prop = SWITCH_USER,
+            .value = {.int32Values = {23,
+                                      static_cast<int32_t>(SwitchUserMessageType::VEHICLE_REQUEST),
+                                      11}},
+    };
+
+    VehiclePropValuePool pool;
+    auto result = toVehiclePropValue(pool, request);
+
+    ASSERT_TRUE(result.ok());
+    EXPECT_THAT(result.value()->timestamp, Gt(0));
+    // Don't rely on real timestamp in tests as the expected and actual objects won't have the same
+    // timestamps. Thus remove the timestamps before comparing them.
+    result.value()->timestamp = 0;
+    EXPECT_THAT(result.value(), Pointee(Eq(expected)));
+}
+
+TEST(UserHalHelperTest, TestFailsSwitchUserRequestToVehiclePropValueWithIncompatibleMessageType) {
+    SwitchUserRequest request{
+            .requestId = 23,
+            .messageType = SwitchUserMessageType::VEHICLE_RESPONSE,
+            .targetUser = {11, GUEST_USER},
+    };
+
+    VehiclePropValuePool pool;
+    auto result = toVehiclePropValue(pool, request);
+
+    EXPECT_FALSE(result.ok());
+}
+
+TEST(UserHalHelperTest, TestInitialUserInfoResponseToVehiclePropValue) {
+    InitialUserInfoResponse response{
+            .requestId = 23,
+            .action = InitialUserInfoResponseAction::CREATE,
+            .userToSwitchOrCreate = {11, GUEST_USER},
+            .userLocales = "en-US,pt-BR",
+            .userNameToCreate = "Owner",
+    };
+    VehiclePropValue expected{
+            .prop = INITIAL_USER_INFO,
+            .value = {.int32Values = {23,
+                                      static_cast<int32_t>(InitialUserInfoResponseAction::CREATE),
+                                      11, GUEST_USER},
+                      .stringValue = "en-US,pt-BR||Owner"},
+    };
+
+    VehiclePropValuePool pool;
+    auto actual = toVehiclePropValue(pool, response);
+
+    ASSERT_THAT(actual, NotNull());
+    EXPECT_THAT(actual->timestamp, Gt(0));
+    actual->timestamp = 0;
+    EXPECT_THAT(actual, Pointee(Eq(expected)));
+}
+
+TEST(UserHalHelperTest, TestSwitchUserResponseToVehiclePropValue) {
+    SwitchUserResponse response{
+            .requestId = 23,
+            .messageType = SwitchUserMessageType::VEHICLE_RESPONSE,
+            .status = SwitchUserStatus::FAILURE,
+            .errorMessage = "random error",
+    };
+    VehiclePropValue expected{
+            .prop = SWITCH_USER,
+            .value = {.int32Values = {23,
+                                      static_cast<int32_t>(SwitchUserMessageType::VEHICLE_RESPONSE),
+                                      static_cast<int32_t>(SwitchUserStatus::FAILURE)},
+                      .stringValue = "random error"},
+    };
+
+    VehiclePropValuePool pool;
+    auto actual = toVehiclePropValue(pool, response);
+
+    ASSERT_THAT(actual, NotNull());
+    EXPECT_THAT(actual->timestamp, Gt(0));
+    actual->timestamp = 0;
+    EXPECT_THAT(actual, Pointee(Eq(expected)));
+}
+
+TEST(UserHalHelperTest, TestCreateUserResponseToVehiclePropValue) {
+    CreateUserResponse response{
+            .requestId = 23,
+            .status = CreateUserStatus::FAILURE,
+            .errorMessage = "random error",
+    };
+    VehiclePropValue expected{
+            .prop = CREATE_USER,
+            .value = {.int32Values = {23, static_cast<int32_t>(CreateUserStatus::FAILURE)},
+                      .stringValue = "random error"},
+    };
+
+    VehiclePropValuePool pool;
+    auto actual = toVehiclePropValue(pool, response);
+
+    ASSERT_THAT(actual, NotNull());
+    EXPECT_THAT(actual->timestamp, Gt(0));
+    actual->timestamp = 0;
+    EXPECT_THAT(actual, Pointee(Eq(expected)));
+}
+
+TEST(UserHalHelperTest, TestUserIdentificationResponseToVehiclePropValue) {
+    UserIdentificationResponse response{
+            .requestId = 23,
+            .numberAssociation = 2,
+            .associations = {{UserIdentificationAssociationType::KEY_FOB,
+                              UserIdentificationAssociationValue::ASSOCIATED_CURRENT_USER},
+                             {UserIdentificationAssociationType::CUSTOM_1,
+                              UserIdentificationAssociationValue::NOT_ASSOCIATED_ANY_USER}},
+            .errorMessage = "random error",
+    };
+    VehiclePropValue expected{
+            .prop = USER_IDENTIFICATION_ASSOCIATION,
+            .value = {.int32Values = {23, 2, USER_ID_ASSOC_KEY_FOB, USER_ID_ASSOC_CURRENT_USER,
+                                      USER_ID_ASSOC_CUSTOM_1, USER_ID_ASSOC_NO_USER},
+                      .stringValue = "random error"},
+    };
+
+    VehiclePropValuePool pool;
+    auto actual = toVehiclePropValue(pool, response);
+
+    ASSERT_THAT(actual, NotNull());
+    EXPECT_THAT(actual->timestamp, Gt(0));
+    actual->timestamp = 0;
+    EXPECT_THAT(actual, Pointee(Eq(expected)));
+}
+
+}  // namespace user_hal_helper
+}  // namespace fake
+}  // namespace vehicle
+}  // namespace automotive
+}  // namespace hardware
+}  // namespace android