Use override on overriding methods - found with clang-tidy.
diff --git a/src/tests/containerizer/routing_tests.cpp b/src/tests/containerizer/routing_tests.cpp
index f2e4622..a030668 100644
--- a/src/tests/containerizer/routing_tests.cpp
+++ b/src/tests/containerizer/routing_tests.cpp
@@ -239,7 +239,7 @@
 class RoutingVethTest : public RoutingAdvancedTest
 {
 protected:
-  virtual void SetUp()
+  void SetUp() override
   {
     RoutingAdvancedTest::SetUp();
 
@@ -251,7 +251,7 @@
     ASSERT_SOME_FALSE(link::exists(TEST_PEER_LINK));
   }
 
-  virtual void TearDown()
+  void TearDown() override
   {
     link::remove(TEST_VETH_LINK);
   }