made MetricValues persistent

MetricValues are persistent for reportUpdates AppendStopsWhenFull and
reportingType different than OnRequest.

Tested:
- New unit tests are passing
- Confirmed MetricValues are preserved after restarting telemetry
  service

Change-Id: I7e1990fb391da9debb0d7df2f1dbda86473350cc
Signed-off-by: Krzysztof Grobelny <krzysztof.grobelny@intel.com>
diff --git a/tests/src/params/report_params.hpp b/tests/src/params/report_params.hpp
index 295be36..db83b0d 100644
--- a/tests/src/params/report_params.hpp
+++ b/tests/src/params/report_params.hpp
@@ -108,6 +108,17 @@
         return metricParametersProperty;
     }
 
+    ReportParams& readings(Readings val)
+    {
+        readingsProperty = std::move(val);
+        return *this;
+    }
+
+    Readings readings() const
+    {
+        return readingsProperty;
+    }
+
   private:
     std::string reportIdProperty = "TestId";
     std::string reportNameProperty = "TestReport";
@@ -135,4 +146,5 @@
              CollectionTimeScope::point,
              CollectionDuration(Milliseconds(0u))}}};
     bool enabledProperty = true;
+    Readings readingsProperty = {};
 };