They are the same.

> You've modified is_deeply such that any additional tests added to @tests must have the results in ascending order for the is_deeply test to be successful.

OK, if you prefer to order them during the tests, so be it.

> There were no duplicates. I added (different) tests such that the result could be in "any order".

hmm ... those seemingly different "any order" arrays are sorted to the same expect-part in the tests.

Hence half of your tests are redundant and violate the DRY principle.

I really don't know how to explain it any better.

FWIW: one actually needs more tests if the input isn't unique, since those cases are different but legit solutions.

    [[2,7,7,15], 9, [0,1]],
    [[2,7,7,15], 9, [0,2]],
[download]

another case for multiple solutions would be

    [[2,7,4,5], 9, [0,1]],
    [[2,7,4,5], 9, [2,3]],
[download]

Consider if a new element is added to @tests:

[[1,2,3,6], 5, [2,1]]
[download]

So, 3+2=5 and the solution is found. In my code, with a sorted $test->[EXPECTED], the test passes; in yours, with an unsorted $test->[EXPECTED], the test fails.

"FWIW: one actually needs more tests if the input isn't unique, since those cases are different but legit solutions. ... another case for multiple solutions would be ..."

That's incorrect. The spec has, in emboldened text (under Contraints): Only one valid answer exists.

— Ken