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in reply to Re: Testing my tests
in thread Testing my tests (mutation testing)

No. I would like to introspect and change my module or application and then run the unchanged tests again. (Updated the original post too with this clarification.)

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Re^3: Testing my tests
by stevieb (Canon) on Feb 26, 2017 at 16:33 UTC

    What about running the tests, then modifying the sub, then running again? Here's a quickly thrown together example (in this example I simply mock out the whole function) to see if this is more along the lines of what you're looking for:

    package Package; { sub perform { return $_[0] + $_[1]; } } package main; { use Mock::Sub; use Test::More; tests(); my $m = Mock::Sub->new; my $changed = $m->mock('Package::perform'); $changed->return_value($_[0] - $_[1]); tests(); done_testing(); sub tests { is Package::perform(5, 5), 10, "5 + 5 = 10"; } }

    Output:

    ok 1 - 5 + 5 = 10 not ok 2 - 5 + 5 = 10 # Failed test '5 + 5 = 10' # at pack.pl line 24. # got: '0' # expected: '10' 1..2 # Looks like you failed 1 test of 2.

    If this example is more along the lines you're after (modifying code on the fly), my Devel::Examine::Subs is designed to alter code within a file (so say you wanted to modify a single line in a single sub within a package, you could (then revert it back), and I could write a mock up example of what it may look like. But perhaps I'm way off here.