$ cat test.t
use Test::More;

subtest foo => sub {
    plan_tests => 3;
    ok 1;
    ok 2;
    ok 3;
};

$ prove -lrv test.t
test.t ..
# Subtest: foo
    ok 1
    ok 2
    ok 3
    1..3
ok 1 - foo
# Tests were run but no plan was declared and done_testing() was not seen.
Dubious, test returned 254 (wstat 65024, 0xfe00)
All 1 subtests passed

##</code><code>##

$ cat test.t

use Test::More;

subtest foo => sub {
    plan_tests => 3;
    ok 1;
    ok 2;
    ok 3;
};

done_testing;

$ prove -lrv test.t
test.t ..
# Subtest: foo
    ok 1
    ok 2
    ok 3
    1..3
ok 1 - foo
1..1
ok
All tests successful.
Files=1, Tests=1, ...