tests: TcpTransport test suite improvements

refs #3306

Change-Id: I3b342b4df13db7996b03de7d1bed65b579798f85
diff --git a/tests/daemon/face/ethernet.t.cpp b/tests/daemon/face/ethernet.t.cpp
index 0098436..2b1d2de 100644
--- a/tests/daemon/face/ethernet.t.cpp
+++ b/tests/daemon/face/ethernet.t.cpp
@@ -34,6 +34,8 @@
 namespace nfd {
 namespace tests {
 
+using nfd::face::tests::NetworkInterfaceFixture;
+
 BOOST_AUTO_TEST_SUITE(Face)
 BOOST_FIXTURE_TEST_SUITE(TestEthernet, NetworkInterfaceFixture)