Add unit tests for utils and refactor Makefiles

1. Add unit tests for utils;
2. Put the common code shared by app and utest into a library, and link the
library to app and utest.
This eliminates the duplicated compiled objects.
3. Update .gitignore

Change-Id: I05ee93c2b23748a1e038eeec3534d49b94911366
Signed-off-by: Lei YU <mine260309@gmail.com>
diff --git a/test/TestI2cOcc.cpp b/test/TestI2cOcc.cpp
new file mode 100644
index 0000000..3fb6e6e
--- /dev/null
+++ b/test/TestI2cOcc.cpp
@@ -0,0 +1,155 @@
+#include <experimental/filesystem>
+#include <fstream>
+#include <gtest/gtest.h>
+#include <string>
+
+#include "i2c_occ.hpp"
+
+#ifdef I2C_OCC
+namespace i2c_occ
+{
+
+namespace fs = std::experimental::filesystem;
+
+using namespace std::string_literals;
+const auto STR_4_0050 = "4-0050"s;
+const auto STR_5_0051 = "5-0051"s;
+const auto STR_6_0056 = "6-0056"s;
+const auto STR_7_0057 = "7-0057"s;
+
+const auto TEST_DIR = "test-dir/"s;
+const auto BASE = TEST_DIR + "sys/bus/i2c/devices/";
+const auto I2C_0 = BASE + "i2c-0";
+const auto I2C_1 = BASE + "i2c-1";
+const auto I2C_2 = BASE + "i2c-2";
+const auto I2C_0_0068 = BASE + "0-0068";
+const auto I2C_4_0050 = BASE + STR_4_0050;
+const auto I2C_5_0051 = BASE + STR_5_0051;
+const auto I2C_6_0056 = BASE + STR_6_0056;
+const auto I2C_7_0057 = BASE + STR_7_0057;
+const auto NAME = "/name";
+const auto P8_OCC_HWMON = "p8-occ-hwmon";
+
+const auto OTHER_STRING = "SomeOtherString123"s;
+
+
+class TestUtilGetOccHwmonDevices : public testing::Test
+{
+public:
+    TestUtilGetOccHwmonDevices()
+    {
+        // Prepare env for test case
+        fs::create_directories(I2C_0);
+        fs::create_directories(I2C_1);
+        fs::create_directories(I2C_2);
+        fs::create_directories(I2C_0_0068);
+        fs::create_directories(I2C_4_0050);
+        fs::create_directories(I2C_5_0051);
+        fs::create_directories(I2C_6_0056);
+        fs::create_directories(I2C_7_0057);
+
+        std::ofstream ofs;
+
+        ofs.open(I2C_0 + NAME); // i2c-0 has empty name
+        ofs.close();
+
+        ofs.open(I2C_1 + NAME);
+        ofs << "some text\n"; // i2c-1/name has some text
+        ofs.close();
+
+        ofs.open(I2C_2 + NAME);
+        ofs << "Aspped i2c"; // i2c-2/name is aspeed i2c
+        ofs.close();
+
+        ofs.open(I2C_0_0068 + NAME);
+        ofs << "other text"; // 0-0068/name is has other text
+        ofs.close();
+
+        ofs.open(I2C_4_0050 + NAME);
+        ofs << "p8-occ-hwmon\n"; // 4-0050/name is p8-occ-hwmon
+        ofs.close();
+
+        ofs.open(I2C_5_0051 + NAME);
+        ofs << "p8-occ-hwmon\n"; // 5-0051/name is p8-occ-hwmon
+        ofs.close();
+
+        ofs.open(I2C_6_0056 + NAME);
+        ofs << "p8-occ-hwmon\n"; // 6-0056/name is p8-occ-hwmon
+        ofs.close();
+
+        ofs.open(I2C_7_0057 + NAME);
+        ofs << "p8-occ-hwmon\n"; // 7-0057/name is p8-occ-hwmon
+        ofs.close();
+    }
+
+    ~TestUtilGetOccHwmonDevices()
+    {
+        // Cleanup test env
+        fs::remove_all(TEST_DIR);
+    }
+};
+
+TEST_F(TestUtilGetOccHwmonDevices, getDevicesOK)
+{
+    // With test env, it shall find all the 4 p8-occ-hwmon devices
+    auto ret = getOccHwmonDevices(BASE.c_str());
+    EXPECT_EQ(4u, ret.size());
+    EXPECT_EQ(STR_4_0050, ret[0]);
+    EXPECT_EQ(STR_5_0051, ret[1]);
+    EXPECT_EQ(STR_6_0056, ret[2]);
+    EXPECT_EQ(STR_7_0057, ret[3]);
+}
+
+TEST_F(TestUtilGetOccHwmonDevices, getDevicesValidDirNoDevices)
+{
+    // Giving a dir without valid devices,
+    // it shall return an empty vector
+    auto ret = getOccHwmonDevices(TEST_DIR.c_str());
+    EXPECT_TRUE(ret.empty());
+}
+
+TEST_F(TestUtilGetOccHwmonDevices, getDevicesDirNotExist)
+{
+    // Giving a dir that does not exist,
+    // it shall return an empty vector
+    auto ret = getOccHwmonDevices((TEST_DIR + "not-exist").c_str());
+    EXPECT_TRUE(ret.empty());
+}
+
+TEST(TestI2cDbusNames, i2cToDbus)
+{
+    // It shall convert 4-0050 to 4_0050
+    auto str = STR_4_0050;
+    i2cToDbus(str);
+    EXPECT_EQ("4_0050", str);
+
+    // It shall not modify for other strings without '-'
+    str = OTHER_STRING;
+    i2cToDbus(str);
+    EXPECT_EQ(OTHER_STRING, str);
+}
+
+TEST(TestI2cDbusNames, dbusToI2c)
+{
+    // It shall convert 4_0050 to 4-0050
+    auto str = "4_0050"s;
+    dbusToI2c(str);
+    EXPECT_EQ(STR_4_0050, str);
+
+    // It shall not modify for other strings without '-'
+    str = OTHER_STRING;
+    dbusToI2c(str);
+    EXPECT_EQ(OTHER_STRING, str);
+}
+
+TEST(TestI2cDbusNames, getI2cDeviceName)
+{
+    auto path = "/org/open_power/control/4_0050"s;
+    auto name = getI2cDeviceName(path);
+    EXPECT_EQ(STR_4_0050, name);
+}
+
+} // namespace i2c_occ
+
+#endif // I2C_OCC
+