tests: move to namespace psync::tests

Change-Id: I462563e8f3d60fbf2a124bad4e412665adeb8186
diff --git a/tests/test-producer-base.cpp b/tests/test-producer-base.cpp
index 468c1d4..11a2699 100644
--- a/tests/test-producer-base.cpp
+++ b/tests/test-producer-base.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2023,  The University of Memphis
+ * Copyright (c) 2014-2024,  The University of Memphis
  *
  * This file is part of PSync.
  * See AUTHORS.md for complete list of PSync authors and contributors.
@@ -24,11 +24,11 @@
 
 #include <ndn-cxx/util/dummy-client-face.hpp>
 
-namespace psync {
+namespace psync::tests {
 
 using ndn::Name;
 
-class ProducerBaseFixture : public tests::KeyChainFixture
+class ProducerBaseFixture : public KeyChainFixture
 {
 protected:
   ndn::DummyClientFace m_face;
@@ -80,4 +80,4 @@
 
 BOOST_AUTO_TEST_SUITE_END()
 
-} // namespace psync
+} // namespace psync::tests