diff --git a/tests/unit/sysutil_test.cpp b/tests/unit/sysutil_test.cpp
new file mode 100644
index 0000000..f469966
--- /dev/null
+++ b/tests/unit/sysutil_test.cpp
@@ -0,0 +1,140 @@
+/*
+ * Copyright 2016 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 <gtest/gtest.h>
+
+#include <string>
+
+#include <android-base/file.h>
+#include <android-base/test_utils.h>
+
+#include "otautil/SysUtil.h"
+
+TEST(SysUtilTest, InvalidArgs) {
+  MemMapping mapping;
+
+  // Invalid argument.
+  ASSERT_EQ(-1, sysMapFile(nullptr, &mapping));
+  ASSERT_EQ(-1, sysMapFile("/somefile", nullptr));
+}
+
+TEST(SysUtilTest, sysMapFileRegularFile) {
+  TemporaryFile temp_file1;
+  std::string content = "abc";
+  ASSERT_TRUE(android::base::WriteStringToFile(content, temp_file1.path));
+
+  // sysMapFile() should map the file to one range.
+  MemMapping mapping;
+  ASSERT_EQ(0, sysMapFile(temp_file1.path, &mapping));
+  ASSERT_NE(nullptr, mapping.addr);
+  ASSERT_EQ(content.size(), mapping.length);
+  ASSERT_EQ(1U, mapping.ranges.size());
+
+  sysReleaseMap(&mapping);
+  ASSERT_EQ(0U, mapping.ranges.size());
+}
+
+TEST(SysUtilTest, sysMapFileBlockMap) {
+  // Create a file that has 10 blocks.
+  TemporaryFile package;
+  std::string content;
+  constexpr size_t file_size = 4096 * 10;
+  content.reserve(file_size);
+  ASSERT_TRUE(android::base::WriteStringToFile(content, package.path));
+
+  TemporaryFile block_map_file;
+  std::string filename = std::string("@") + block_map_file.path;
+  MemMapping mapping;
+
+  // One range.
+  std::string block_map_content = std::string(package.path) + "\n40960 4096\n1\n0 10\n";
+  ASSERT_TRUE(android::base::WriteStringToFile(block_map_content, block_map_file.path));
+
+  ASSERT_EQ(0, sysMapFile(filename.c_str(), &mapping));
+  ASSERT_EQ(file_size, mapping.length);
+  ASSERT_EQ(1U, mapping.ranges.size());
+
+  // It's okay to not have the trailing '\n'.
+  block_map_content = std::string(package.path) + "\n40960 4096\n1\n0 10";
+  ASSERT_TRUE(android::base::WriteStringToFile(block_map_content, block_map_file.path));
+
+  ASSERT_EQ(0, sysMapFile(filename.c_str(), &mapping));
+  ASSERT_EQ(file_size, mapping.length);
+  ASSERT_EQ(1U, mapping.ranges.size());
+
+  // Or having multiple trailing '\n's.
+  block_map_content = std::string(package.path) + "\n40960 4096\n1\n0 10\n\n\n";
+  ASSERT_TRUE(android::base::WriteStringToFile(block_map_content, block_map_file.path));
+
+  ASSERT_EQ(0, sysMapFile(filename.c_str(), &mapping));
+  ASSERT_EQ(file_size, mapping.length);
+  ASSERT_EQ(1U, mapping.ranges.size());
+
+  // Multiple ranges.
+  block_map_content = std::string(package.path) + "\n40960 4096\n3\n0 3\n3 5\n5 10\n";
+  ASSERT_TRUE(android::base::WriteStringToFile(block_map_content, block_map_file.path));
+
+  ASSERT_EQ(0, sysMapFile(filename.c_str(), &mapping));
+  ASSERT_EQ(file_size, mapping.length);
+  ASSERT_EQ(3U, mapping.ranges.size());
+
+  sysReleaseMap(&mapping);
+  ASSERT_EQ(0U, mapping.ranges.size());
+}
+
+TEST(SysUtilTest, sysMapFileBlockMapInvalidBlockMap) {
+  MemMapping mapping;
+  TemporaryFile temp_file;
+  std::string filename = std::string("@") + temp_file.path;
+
+  // Block map file is too short.
+  ASSERT_TRUE(android::base::WriteStringToFile("/somefile\n", temp_file.path));
+  ASSERT_EQ(-1, sysMapFile(filename.c_str(), &mapping));
+
+  ASSERT_TRUE(android::base::WriteStringToFile("/somefile\n4096 4096\n0\n", temp_file.path));
+  ASSERT_EQ(-1, sysMapFile(filename.c_str(), &mapping));
+
+  // Block map file has unexpected number of lines.
+  ASSERT_TRUE(android::base::WriteStringToFile("/somefile\n4096 4096\n1\n", temp_file.path));
+  ASSERT_EQ(-1, sysMapFile(filename.c_str(), &mapping));
+
+  ASSERT_TRUE(android::base::WriteStringToFile("/somefile\n4096 4096\n2\n0 1\n", temp_file.path));
+  ASSERT_EQ(-1, sysMapFile(filename.c_str(), &mapping));
+
+  // Invalid size/blksize/range_count.
+  ASSERT_TRUE(android::base::WriteStringToFile("/somefile\nabc 4096\n1\n0 1\n", temp_file.path));
+  ASSERT_EQ(-1, sysMapFile(filename.c_str(), &mapping));
+
+  ASSERT_TRUE(android::base::WriteStringToFile("/somefile\n4096 4096\n\n0 1\n", temp_file.path));
+  ASSERT_EQ(-1, sysMapFile(filename.c_str(), &mapping));
+
+  // size/blksize/range_count don't match.
+  ASSERT_TRUE(android::base::WriteStringToFile("/somefile\n0 4096\n1\n0 1\n", temp_file.path));
+  ASSERT_EQ(-1, sysMapFile(filename.c_str(), &mapping));
+
+  ASSERT_TRUE(android::base::WriteStringToFile("/somefile\n4096 0\n1\n0 1\n", temp_file.path));
+  ASSERT_EQ(-1, sysMapFile(filename.c_str(), &mapping));
+
+  ASSERT_TRUE(android::base::WriteStringToFile("/somefile\n4096 4096\n0\n0 1\n", temp_file.path));
+  ASSERT_EQ(-1, sysMapFile(filename.c_str(), &mapping));
+
+  // Invalid block dev path.
+  ASSERT_TRUE(android::base::WriteStringToFile("/doesntexist\n4096 4096\n1\n0 1\n", temp_file.path));
+  ASSERT_EQ(-1, sysMapFile(filename.c_str(), &mapping));
+
+  sysReleaseMap(&mapping);
+  ASSERT_EQ(0U, mapping.ranges.size());
+}