change RequestID to RequestId

Change-Id: Icb426614f391d2828c906155a0d37fd7da7c13f8
diff --git a/tests/unit-tests/challenge-credential.t.cpp b/tests/unit-tests/challenge-credential.t.cpp
index e048e29..8a301df 100644
--- a/tests/unit-tests/challenge-credential.t.cpp
+++ b/tests/unit-tests/challenge-credential.t.cpp
@@ -53,7 +53,7 @@
   auto identityA = addIdentity(Name("/example"));
   auto keyA = identityA.getDefaultKey();
   auto certA = key.getDefaultCertificate();
-  RequestID requestId = {1,2,3,4,5,6,7,8};
+  RequestId requestId = {1,2,3,4,5,6,7,8};
   ca::RequestState state(Name("/example"), requestId, RequestType::NEW, Status::BEFORE_CHALLENGE, certA, makeEmptyBlock(ndn::tlv::ContentType_Key));
 
   // create requester's credential