tests: namespace cleanup

Change-Id: I6b9ee82a4cb3b97c82ea111495ec07efddc8d825
diff --git a/tests/test-statistics.cpp b/tests/test-statistics.cpp
index 43bbf70..e4c8a23 100644
--- a/tests/test-statistics.cpp
+++ b/tests/test-statistics.cpp
@@ -29,8 +29,7 @@
 
 #include <boost/lexical_cast.hpp>
 
-namespace nlsr {
-namespace test {
+namespace nlsr::tests {
 
 class StatisticsFixture : public IoKeyChainFixture
 {
@@ -329,5 +328,4 @@
 
 BOOST_AUTO_TEST_SUITE_END()
 
-} // namespace test
-} // namespace nlsr
+} // namespace nlsr::tests