The test interfaces EXEC command is intended for the factory checkout of network interfaces. It is not intended for diagnosing problems with an operational router, i've used it and i got the same results you've got. The test interfaces output does not report correct results if the router is attached to a "live" network. For each network interface that has an IP address that can be tested in loopback (MCI and ciscoBus Ethernet and all serial interfaces), the test interfaces command sends a series of ICMP echoes. Error counters are examined to determine the operational status of the interface.
