for injection, add handler: add unit-tests

Add a handler to enable dependency injection for testing.  This is a
required step to use mocks.
Add the unit-tests.

Tested: Verified the new unit-tests ran.
Change-Id: I991849e6df2c3e74f59145a966048fc6825560db
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/test/handler_mock.hpp b/test/handler_mock.hpp
new file mode 100644
index 0000000..1ef94a4
--- /dev/null
+++ b/test/handler_mock.hpp
@@ -0,0 +1,22 @@
+#pragma once
+
+#include "handler.hpp"
+
+#include <cstdint>
+#include <string>
+
+#include <gmock/gmock.h>
+
+namespace ethstats
+{
+
+class HandlerMock : public EthStatsInterface
+{
+  public:
+    ~HandlerMock() = default;
+
+    MOCK_CONST_METHOD1(validIfNameAndField, bool(const std::string&));
+    MOCK_CONST_METHOD1(readStatistic, std::uint64_t(const std::string&));
+};
+
+} // namespace ethstats