Array Subset does not work as expected on indexed / flat arrays

[mrhn]

Q	A
PHPUnit version	7.1.4
PHP version	7.1.16
Installation Method	Composer

Digging up a older issue which i do not feel is explained properly, see #2781 and #2069.

In regards to the comment you wrote, "is it fixed in #2237?", no it is not. The the usage of array_replace_recursive and how indexed arrays work in PHP is the problem here. This seem to confuse a lot of people me included. If it works as intended is up for debate, but i will try to explain the confusion.

In set theories the set {1,2,3} will have the subset {2,3}. If we use array_replace_recursive with this. It will use the array [0 => 1, 1 => 2, 2 => 3] and replace the keys with the subset [0 => 2, 1 => 3], which for this usage of array_replace_recursive should instead be [1 => 2, 2 => 3], to make {2,3} pass as a subset, with the way the current code is written. Yes i agree, that arrays are not sets, but i feel this is how people logically assert these things in their minds. So replacing array_replace_recursive on indexed arrays would solve this as the implementer @marcioAlmada of the subset class has suggested in @2069.

[pfrenssen]

@marcioAlmada has explained in #2069 (comment) that the current implementation of ArraySubset is only intended to be used with associative arrays. He proposed to use array_intersect() for indexed arrays in that comment.

I have tried this but it doesn't work as expected since array_intersect() will always do a string comparison on the array contents. It does not support strict comparisons or nested arrays.

Another solution is to recurse over the data set and compare values directly. I've proposed a fix in #3161 which supports both flat and multidimensional indexed arrays, and is fully backwards compatible with the current implementation for associative arrays. All the original tests are untouched and passing.