We do not have a separate test case for MPLS Labels. LDP does have some negative test cases on valid label ranges etc.
TPK-1071 - CTS LDP Test Package
TPK-1070 - CTS RSVP Test Package
TPK-1072 - CTS BGP-VPLS Test Package
TPK-1078 - CTS MPLS-TP OAM Test Package
Covers LSP Ping for MPLS-TP
TPK-0025 - CTS PWE3 ETHERNET ENCAP Test Package
Covers VCCV OAM