public function testContains() { $elements = [1, 'A' => 'a', 2, 'null' => null, 3, 'A2' => 'a', 'zero' => 0]; $collection = new ArrayCollection($elements); $this->assertTrue($collection->contains(0), 'Contains Zero'); $this->assertTrue($collection->contains('a'), 'Contains "a"'); $this->assertTrue($collection->contains(null), 'Contains Null'); $this->assertFalse($collection->contains('non-existent'), "Doesn't contain an element"); }