diff --git a/tests/Android.mk b/tests/Android.mk
index e526630..4e125cc 100644
--- a/tests/Android.mk
+++ b/tests/Android.mk
@@ -89,6 +89,10 @@
 LOCAL_CFLAGS += -DAB_OTA_UPDATER=1
 endif
 
+ifeq ($(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_SUPPORTS_VERITY),true)
+LOCAL_CFLAGS += -DPRODUCT_SUPPORTS_VERITY=1
+endif
+
 LOCAL_MODULE := recovery_component_test
 LOCAL_COMPATIBILITY_SUITE := device-tests
 LOCAL_C_INCLUDES := bootable/recovery
@@ -101,6 +105,7 @@
     component/sideload_test.cpp \
     component/uncrypt_test.cpp \
     component/updater_test.cpp \
+    component/update_verifier_test.cpp \
     component/verifier_test.cpp
 
 LOCAL_FORCE_STATIC_EXECUTABLE := true
@@ -128,6 +133,7 @@
     libverifier \
     libotautil \
     libmounts \
+    libupdate_verifier \
     libdivsufsort \
     libdivsufsort64 \
     libfs_mgr \
diff --git a/tests/component/update_verifier_test.cpp b/tests/component/update_verifier_test.cpp
new file mode 100644
index 0000000..73b4478
--- /dev/null
+++ b/tests/component/update_verifier_test.cpp
@@ -0,0 +1,83 @@
+/*
+ * Copyright (C) 2017 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 <string>
+
+#include <android-base/file.h>
+#include <android-base/test_utils.h>
+#include <gtest/gtest.h>
+#include <update_verifier/update_verifier.h>
+
+class UpdateVerifierTest : public ::testing::Test {
+ protected:
+  void SetUp() override {
+#ifdef PRODUCT_SUPPORTS_VERITY
+    verity_supported = true;
+#else
+    verity_supported = false;
+#endif
+  }
+
+  bool verity_supported;
+};
+
+TEST_F(UpdateVerifierTest, verify_image_no_care_map) {
+  // Non-existing care_map is allowed.
+  ASSERT_TRUE(verify_image("/doesntexist"));
+}
+
+TEST_F(UpdateVerifierTest, verify_image_smoke) {
+  // This test relies on dm-verity support.
+  if (!verity_supported) {
+    GTEST_LOG_(INFO) << "Test skipped on devices without dm-verity support.";
+    return;
+  }
+
+  // The care map file can have only two or four lines.
+  TemporaryFile temp_file;
+  std::string content = "system\n2,0,1";
+  ASSERT_TRUE(android::base::WriteStringToFile(content, temp_file.path));
+  ASSERT_TRUE(verify_image(temp_file.path));
+
+  // Leading and trailing newlines should be accepted.
+  ASSERT_TRUE(android::base::WriteStringToFile("\n" + content + "\n\n", temp_file.path));
+  ASSERT_TRUE(verify_image(temp_file.path));
+}
+
+TEST_F(UpdateVerifierTest, verify_image_wrong_lines) {
+  // The care map file can have only two or four lines.
+  TemporaryFile temp_file;
+  ASSERT_FALSE(verify_image(temp_file.path));
+
+  ASSERT_TRUE(android::base::WriteStringToFile("line1", temp_file.path));
+  ASSERT_FALSE(verify_image(temp_file.path));
+
+  ASSERT_TRUE(android::base::WriteStringToFile("line1\nline2\nline3", temp_file.path));
+  ASSERT_FALSE(verify_image(temp_file.path));
+}
+
+TEST_F(UpdateVerifierTest, verify_image_malformed_care_map) {
+  // This test relies on dm-verity support.
+  if (!verity_supported) {
+    GTEST_LOG_(INFO) << "Test skipped on devices without dm-verity support.";
+    return;
+  }
+
+  TemporaryFile temp_file;
+  std::string content = "system\n2,1,0";
+  ASSERT_TRUE(android::base::WriteStringToFile(content, temp_file.path));
+  ASSERT_FALSE(verify_image(temp_file.path));
+}
diff --git a/update_verifier/Android.mk b/update_verifier/Android.mk
index 1acd5ec..37d9bfe 100644
--- a/update_verifier/Android.mk
+++ b/update_verifier/Android.mk
@@ -14,12 +14,43 @@
 
 LOCAL_PATH := $(call my-dir)
 
+# libupdate_verifier (static library)
+# ===============================
 include $(CLEAR_VARS)
 
-LOCAL_CLANG := true
-LOCAL_SRC_FILES := update_verifier.cpp
+LOCAL_SRC_FILES := \
+    update_verifier.cpp
+
+LOCAL_MODULE := libupdate_verifier
+LOCAL_SHARED_LIBRARIES := \
+    libbase \
+    libcutils \
+    android.hardware.boot@1.0
+
+LOCAL_CFLAGS := -Wall -Werror
+
+LOCAL_EXPORT_C_INCLUDE_DIRS := \
+    $(LOCAL_PATH)/include
+
+LOCAL_C_INCLUDES := \
+    $(LOCAL_PATH)/include
+
+ifeq ($(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_SUPPORTS_VERITY),true)
+LOCAL_CFLAGS += -DPRODUCT_SUPPORTS_VERITY=1
+endif
+
+include $(BUILD_STATIC_LIBRARY)
+
+# update_verifier (executable)
+# ===============================
+include $(CLEAR_VARS)
+
+LOCAL_SRC_FILES := \
+    update_verifier_main.cpp
 
 LOCAL_MODULE := update_verifier
+LOCAL_STATIC_LIBRARIES := \
+    libupdate_verifier
 LOCAL_SHARED_LIBRARIES := \
     libbase \
     libcutils \
@@ -29,13 +60,8 @@
     libhidlbase \
     android.hardware.boot@1.0
 
-LOCAL_CFLAGS := -Werror
-LOCAL_C_INCLUDES += $(LOCAL_PATH)/..
+LOCAL_CFLAGS := -Wall -Werror
 
 LOCAL_INIT_RC := update_verifier.rc
 
-ifeq ($(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_SUPPORTS_VERITY),true)
-    LOCAL_CFLAGS += -DPRODUCT_SUPPORTS_VERITY=1
-endif
-
 include $(BUILD_EXECUTABLE)
diff --git a/update_verifier/include/update_verifier/update_verifier.h b/update_verifier/include/update_verifier/update_verifier.h
new file mode 100644
index 0000000..16b394e
--- /dev/null
+++ b/update_verifier/include/update_verifier/update_verifier.h
@@ -0,0 +1,24 @@
+/*
+ * Copyright (C) 2017 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 <string>
+
+int update_verifier(int argc, char** argv);
+
+// Exposed for testing purpose.
+bool verify_image(const std::string& care_map_name);
diff --git a/update_verifier/update_verifier.cpp b/update_verifier/update_verifier.cpp
index 350020f..1950cbd 100644
--- a/update_verifier/update_verifier.cpp
+++ b/update_verifier/update_verifier.cpp
@@ -35,6 +35,8 @@
  * verifier reaches the end after the verification.
  */
 
+#include "update_verifier/update_verifier.h"
+
 #include <dirent.h>
 #include <errno.h>
 #include <fcntl.h>
@@ -59,12 +61,6 @@
 using android::hardware::boot::V1_0::BoolResult;
 using android::hardware::boot::V1_0::CommandResult;
 
-constexpr auto CARE_MAP_FILE = "/data/ota_package/care_map.txt";
-constexpr auto DM_PATH_PREFIX = "/sys/block/";
-constexpr auto DM_PATH_SUFFIX = "/dm/name";
-constexpr auto DEV_PATH = "/dev/block/";
-constexpr int BLOCKSIZE = 4096;
-
 // Find directories in format of "/sys/block/dm-X".
 static int dm_name_filter(const dirent* de) {
   if (android::base::StartsWith(de->d_name, "dm-")) {
@@ -82,6 +78,7 @@
   // (or "vendor"), then dm-X is a dm-wrapped system/vendor partition.
   // Afterwards, update_verifier will read every block on the care_map_file of
   // "/dev/block/dm-X" to ensure the partition's integrity.
+  static constexpr auto DM_PATH_PREFIX = "/sys/block/";
   dirent** namelist;
   int n = scandir(DM_PATH_PREFIX, &namelist, dm_name_filter, alphasort);
   if (n == -1) {
@@ -93,6 +90,8 @@
     return false;
   }
 
+  static constexpr auto DM_PATH_SUFFIX = "/dm/name";
+  static constexpr auto DEV_PATH = "/dev/block/";
   std::string dm_block_device;
   while (n--) {
     std::string path = DM_PATH_PREFIX + std::string(namelist[n]->d_name) + DM_PATH_SUFFIX;
@@ -143,6 +142,7 @@
       return false;
     }
 
+    static constexpr int BLOCKSIZE = 4096;
     if (lseek64(fd.get(), static_cast<off64_t>(range_start) * BLOCKSIZE, SEEK_SET) == -1) {
       PLOG(ERROR) << "lseek to " << range_start << " failed";
       return false;
@@ -161,7 +161,7 @@
   return true;
 }
 
-static bool verify_image(const std::string& care_map_name) {
+bool verify_image(const std::string& care_map_name) {
     android::base::unique_fd care_map_fd(TEMP_FAILURE_RETRY(open(care_map_name.c_str(), O_RDONLY)));
     // If the device is flashed before the current boot, it may not have care_map.txt
     // in /data/ota_package. To allow the device to continue booting in this situation,
@@ -205,7 +205,7 @@
   while (true) pause();
 }
 
-int main(int argc, char** argv) {
+int update_verifier(int argc, char** argv) {
   for (int i = 1; i < argc; i++) {
     LOG(INFO) << "Started with arg " << i << ": " << argv[i];
   }
@@ -238,6 +238,7 @@
       return reboot_device();
     }
 
+    static constexpr auto CARE_MAP_FILE = "/data/ota_package/care_map.txt";
     if (!verify_image(CARE_MAP_FILE)) {
       LOG(ERROR) << "Failed to verify all blocks in care map file.";
       return reboot_device();
diff --git a/update_verifier/update_verifier_main.cpp b/update_verifier/update_verifier_main.cpp
new file mode 100644
index 0000000..46e8bbb
--- /dev/null
+++ b/update_verifier/update_verifier_main.cpp
@@ -0,0 +1,23 @@
+/*
+ * Copyright (C) 2017 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.
+ */
+
+// See the comments in update_verifier.cpp.
+
+#include "update_verifier/update_verifier.h"
+
+int main(int argc, char** argv) {
+  return update_verifier(argc, argv);
+}