Add IdentityManagementV2TimeFixture for tests

Change-Id: I11aa582a7bb875d083285bc35bbfb056291e2374
diff --git a/tests/identity-management-fixture.hpp b/tests/identity-management-fixture.hpp
index 9c9a4b5..8a80da8 100644
--- a/tests/identity-management-fixture.hpp
+++ b/tests/identity-management-fixture.hpp
@@ -136,6 +136,14 @@
 {
 };
 
+/** \brief convenience base class for inheriting from both UnitTestTimeFixture
+ *         and IdentityManagementV2Fixture
+ */
+class IdentityManagementV2TimeFixture : public UnitTestTimeFixture
+                                      , public IdentityManagementV2Fixture
+{
+};
+
 } // namespace tests
 } // namespace ndncert
 } // namespace ndn