tests: Fix test cases for ImplictSha256DigestComponent

Change-Id: Ibce7419ba8b2607039844e26a64eb554b4568c5c
Refs: #2172
diff --git a/src/common.hpp b/src/common.hpp
index ee122d3..3611c02 100644
--- a/src/common.hpp
+++ b/src/common.hpp
@@ -51,6 +51,7 @@
 using ndn::Face;
 using ndn::Block;
 using ndn::Name;
+namespace name = ndn::name;
 using ndn::Interest;
 using ndn::Selectors;
 using ndn::Exclude;