Thanks for all your answers, but I think I should re explain my need. I don't want to skip the tests. The default fail fast mode of maven suits me (section 6.1.8 http://www.sonatype.com/books/mvnref-book/reference/running-sect-options.html ).
I just want to run my custom mojo just after my tests failures and just before the end of the maven execution (if there is build failures, maven do not even finishes the current test phase). Regards, Xavier