update header files in tests

Change-Id: Ibfffb9367349f58eeb193350bad34fdfccd8c553
diff --git a/tests/database-fixture.hpp b/tests/database-fixture.hpp
index c7e04bb..4223c98 100644
--- a/tests/database-fixture.hpp
+++ b/tests/database-fixture.hpp
@@ -23,12 +23,18 @@
 #define NDNCERT_TESTS_DATABASE_FIXTURE_HPP
 
 #include "identity-management-fixture.hpp"
+#include "unit-test-time-fixture.hpp"
 #include <boost/filesystem.hpp>
 
 namespace ndn {
 namespace ndncert {
 namespace tests {
 
+class IdentityManagementTimeFixture : public UnitTestTimeFixture
+                                    , public IdentityManagementFixture
+{
+};
+
 class DatabaseFixture : public IdentityManagementTimeFixture
 {
 public: