diff --git a/tools/fs_config/Android.mk b/tools/fs_config/Android.mk
index 65f8a08..4a2b566 100644
--- a/tools/fs_config/Android.mk
+++ b/tools/fs_config/Android.mk
@@ -195,3 +195,36 @@
 my_fs_config_h :=
 fs_config_generate_bin :=
 my_gen_oem_aid :=
+
+# -----------------------------------------------------------------------------
+# Unit tests.
+# -----------------------------------------------------------------------------
+
+test_c_flags := \
+    -fstack-protector-all \
+    -g \
+    -Wall \
+    -Wextra \
+    -Werror \
+    -fno-builtin \
+    -DANDROID_FILESYSTEM_CONFIG='"android_filesystem_config_test_data.h"'
+
+##################################
+# test executable
+include $(CLEAR_VARS)
+LOCAL_MODULE := fs_config_generate_test
+LOCAL_SRC_FILES := fs_config_generate.c
+LOCAL_SHARED_LIBRARIES := libcutils
+LOCAL_CFLAGS := $(test_c_flags)
+LOCAL_MODULE_RELATIVE_PATH := fs_config-unit-tests
+LOCAL_GTEST := false
+include $(BUILD_HOST_NATIVE_TEST)
+
+##################################
+# gTest tool
+include $(CLEAR_VARS)
+LOCAL_MODULE := fs_config-unit-tests
+LOCAL_CFLAGS += $(test_c_flags) -DHOST
+LOCAL_SHARED_LIBRARIES := liblog libcutils libbase
+LOCAL_SRC_FILES := fs_config_test.cpp
+include $(BUILD_HOST_NATIVE_TEST)
diff --git a/tools/fs_config/android_filesystem_config_test_data.h b/tools/fs_config/android_filesystem_config_test_data.h
new file mode 100644
index 0000000..2b98415
--- /dev/null
+++ b/tools/fs_config/android_filesystem_config_test_data.h
@@ -0,0 +1,40 @@
+/*
+ * 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 <private/android_filesystem_config.h>
+
+/* Test Data */
+
+#undef NO_ANDROID_FILESYSTEM_CONFIG_DEVICE_DIRS
+#undef NO_ANDROID_FILESYSTEM_CONFIG_DEVICE_FILES
+
+static const struct fs_path_config android_device_dirs[] = {
+    {00555, AID_ROOT, AID_SYSTEM, 0, "system/etc"},
+    {00555, AID_ROOT, AID_SYSTEM, 0, "vendor/etc"},
+    {00555, AID_ROOT, AID_SYSTEM, 0, "oem/etc"},
+    {00555, AID_ROOT, AID_SYSTEM, 0, "odm/etc"},
+};
+
+static const struct fs_path_config android_device_files[] = {
+    {00444, AID_ROOT, AID_SYSTEM, 0, "system/etc/fs_config_dirs"},
+    {00444, AID_ROOT, AID_SYSTEM, 0, "vendor/etc/fs_config_dirs"},
+    {00444, AID_ROOT, AID_SYSTEM, 0, "oem/etc/fs_config_dirs"},
+    {00444, AID_ROOT, AID_SYSTEM, 0, "odm/etc/fs_config_dirs"},
+    {00444, AID_ROOT, AID_SYSTEM, 0, "system/etc/fs_config_files"},
+    {00444, AID_ROOT, AID_SYSTEM, 0, "vendor/etc/fs_config_files"},
+    {00444, AID_ROOT, AID_SYSTEM, 0, "oem/etc/fs_config_files"},
+    {00444, AID_ROOT, AID_SYSTEM, 0, "odm/etc/fs_config_files"},
+};
diff --git a/tools/fs_config/fs_config_generate.c b/tools/fs_config/fs_config_generate.c
index c06213f..e08642f 100644
--- a/tools/fs_config/fs_config_generate.c
+++ b/tools/fs_config/fs_config_generate.c
@@ -28,7 +28,11 @@
  * the binary format used in the /system/etc/fs_config_dirs and
  * the /system/etc/fs_config_files to be used by the runtimes.
  */
+#ifdef ANDROID_FILESYSTEM_CONFIG
+#include ANDROID_FILESYSTEM_CONFIG
+#else
 #include "android_filesystem_config.h"
+#endif
 
 #ifdef NO_ANDROID_FILESYSTEM_CONFIG_DEVICE_DIRS
   static const struct fs_path_config android_device_dirs[] = {
diff --git a/tools/fs_config/fs_config_test.cpp b/tools/fs_config/fs_config_test.cpp
new file mode 100644
index 0000000..49e89e3
--- /dev/null
+++ b/tools/fs_config/fs_config_test.cpp
@@ -0,0 +1,86 @@
+/*
+ * 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 <stdio.h>
+#include <sys/cdefs.h>
+
+#include <string>
+
+#include <android-base/file.h>
+#include <android-base/macros.h>
+#include <android-base/stringprintf.h>
+#include <gtest/gtest.h>
+#include <private/android_filesystem_config.h>
+#include <private/fs_config.h>
+
+#include "android_filesystem_config_test_data.h"
+
+// must run test in the test directory
+const static char fs_config_generate_command[] = "./fs_config_generate_test";
+
+static std::string popenToString(std::string command) {
+  std::string ret;
+
+  FILE* fp = popen(command.c_str(), "r");
+  if (fp) {
+    if (!android::base::ReadFdToString(fileno(fp), &ret)) ret = "";
+    pclose(fp);
+  }
+  return ret;
+}
+
+static void confirm(std::string&& data, const fs_path_config* config,
+                    ssize_t num_config) {
+  const struct fs_path_config_from_file* pc =
+      reinterpret_cast<const fs_path_config_from_file*>(data.c_str());
+  size_t len = data.size();
+
+  ASSERT_TRUE(config != NULL);
+  ASSERT_LT(0, num_config);
+
+  while (len > 0) {
+    uint16_t host_len = pc->len;
+    if (host_len > len) break;
+
+    EXPECT_EQ(config->mode, pc->mode);
+    EXPECT_EQ(config->uid, pc->uid);
+    EXPECT_EQ(config->gid, pc->gid);
+    EXPECT_EQ(config->capabilities, pc->capabilities);
+    EXPECT_STREQ(config->prefix, pc->prefix);
+
+    EXPECT_LT(0, num_config);
+    --num_config;
+    if (num_config >= 0) ++config;
+    pc = reinterpret_cast<const fs_path_config_from_file*>(
+        reinterpret_cast<const char*>(pc) + host_len);
+    len -= host_len;
+  }
+  EXPECT_EQ(0, num_config);
+}
+
+/* See local android_filesystem_config.h for test data */
+
+TEST(fs_conf_test, dirs) {
+  confirm(popenToString(
+              android::base::StringPrintf("%s -D", fs_config_generate_command)),
+          android_device_dirs, arraysize(android_device_dirs));
+}
+
+TEST(fs_conf_test, files) {
+  confirm(popenToString(
+              android::base::StringPrintf("%s -F", fs_config_generate_command)),
+          android_device_files, arraysize(android_device_files));
+}