NFD

On one of the Jenkins agents for macOS Catalina, the Face/TestMulticastEthernetTransport/NetifStateChange consistently fails when it attempts to use the awdl0 (Apple Wireless Direct Link) interface (which is administratively up, but is not RUNNING). However, I have confirmed that it still fails on macOS when this test case attempts to use a standard Ethernet interface that is also administratively up, but not RUNNING.
Davide and I have determined that this issue is likely caused by a combination of the following two issues:

• EthernetTransport is not initially set to TransportState::DOWN when the underlying interface is initially not InterfaceState::RUNNING.
• EthernetFixture uses any interface that is administratively up but not necessarily InterfaceState::RUNNING, while the test case in question assumes that the transport is initially TransportState::UP (not guaranteed once the previous point is fixed).