ca: fallback to CA identity key to sign prefix registrations

Change-Id: I19968754b5693a664fd92a28dddd636535b81fa6
diff --git a/tests/unit-tests/requester.t.cpp b/tests/unit-tests/requester.t.cpp
index a3fa8d5..03cb3de 100644
--- a/tests/unit-tests/requester.t.cpp
+++ b/tests/unit-tests/requester.t.cpp
@@ -77,6 +77,7 @@
   availableNames.emplace_back("/site1");
   availableNames.emplace_back("/site2");
 
+  m_keyChain.createIdentity(Name("/ndn"));
   ndn::DummyClientFace face(m_io, m_keyChain, {true, true});
   ca::CaModule ca(face, m_keyChain, "tests/unit-tests/config-files/config-ca-5", "ca-storage-memory");