Verify the value of the tempX_label file

- The intent behind this commit is to verify the value of
  the tempX_label file.

- In the future, the value of this file will be changed to
  `D0000002` (OCC sensor ID).
  - OCC Sensor Ids(D0000002)
  - First byte is type                 - D0
  - Second byte is reserved            - 00
  - Third+Fourth bytes are instance id - 0002

Tested: built openpower-occ-control successfully and unit test worked

Signed-off-by: George Liu <liuxiwei@inspur.com>
Change-Id: I5e89ce9592898f79b9fe926dd7bbe5691bf535a5
diff --git a/test/utest.cpp b/test/utest.cpp
index 04fa492..ff75a60 100644
--- a/test/utest.cpp
+++ b/test/utest.cpp
@@ -1,4 +1,5 @@
 #include "powercap.hpp"
+#include "utils.hpp"
 
 #include <experimental/filesystem>
 #include <occ_events.hpp>
@@ -7,6 +8,7 @@
 #include <gtest/gtest.h>
 
 using namespace open_power::occ;
+using namespace open_power::occ::utils;
 
 class VerifyOccInput : public ::testing::Test
 {
@@ -66,3 +68,17 @@
 
     EXPECT_STREQ(parsed.c_str(), "bar");
 }
+
+TEST(VerifyLabelValue, checkLabelValue)
+{
+    const std::string value = "D0000002";
+
+    auto labelValue = checkLabelValue(value);
+    EXPECT_NE(labelValue, std::nullopt);
+
+    std::string reType = "D0";
+    uint16_t reID = 2;
+    auto& [type, instanceID] = *labelValue;
+    EXPECT_EQ(type, reType);
+    EXPECT_EQ(instanceID, reID);
+}