Careful with this method. It can lose information.
The keys will not be changed, thus possibly overwrite each other.
TODO: check if it can be replace by Hash::flatten() or Utility::flatten().
/**
* UtilityTest::testArrayFlattenAndPreserveKeys()
*
* @covers ::arrayFlatten
* @return void
*/
public function testArrayFlattenAndPreserveKeys()
{
$array = [0 => 1, 1 => ['c' => ['d' => ['g', 'h' => true]]], 2 => 'm'];
$res = Utility::arrayFlatten($array, true);
$expected = [0 => 'g', 'h' => true, 2 => 'm'];
$this->assertSame($expected, $res);
}
