One quick test to prove L2VPN is up and should be working is by issuing a Psuedowire ping:
ping mpls pseudowire <dst ip> <VC ID>
If that ping succeeds, we can conclude that the L2VPN control-plane is setup correctly for that VC and that our dataplane has correct labels and is forwarding correctly.
PE#pin mpl pse x.x.80.79 2498079
Success rate is 100 percent (5/5), round-trip min/avg/max = 8/8/12 ms
Success rate is 0 percent (0/5)
Thank you very much.
Adding to what Victor mentioned below, there might be situations where even when your labels and forwarding in the MPLS plane is fine, your l2vpn circuit might not be working fine. You can attach a PC or a virtual host as part of the attachment circuit. and perform a ping test from end to end.
An easy way to verify if your link towards CE is working fine or not is to remove any l2vpn config on the PE on the CE facing interface. Configure an IP address of the same subnet as the CE and perform a ping. This will help proving that your CE facing link is working fine.
Hope this helps.