Functional\Tests\ReindexTest::testDuplicateKeys PHP Method

    public function testDuplicateKeys()
    {
        $fn = function ($v, $k, $collection) {
            InvalidArgumentException::assertCollection($collection, __FUNCTION__, 3);
            return $k[0];
        };
        $this->assertSame(['k' => 'val2'], reindex($this->hash, $fn));
    }