The sort should also be numeric.

    hash_slice => sub {
        my %ha; @ha{0..$#numbers} = @numbers;
        delete @ha{@indices};
        my @output = @ha{sort {$a <=> $b} keys %ha};
        join("\0", @output) eq join("\0", @expect) or die if TEST;
    },
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Update: Although I now see Choroba has already done that in 11123952.