Assuming that whatever you're running (i think prove does) uses exit codes on failure, something simple like this would work (bash syntax): 
0 3 * * * prove foo.t > /tmp/prove$$ 2>&1 || cat /tmp/prove$$

[download]
And it relies on cron's behavior of emailing you whatever output is generated by a job -- here we're printing the whole output iff it failed..

In reply to Re: Reporting test failures within cron by davidrw
in thread Reporting test failures within cron by tomhukins

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