public function testFieldPosition()
 {
     $compositeOuter = new CompositeField(new TextField('A'), new TextField('B'), $compositeInner = new CompositeField(new TextField('C1'), new TextField('C2')), new TextField('D'));
     $this->assertEquals(0, $compositeOuter->fieldPosition('A'));
     $this->assertEquals(1, $compositeOuter->fieldPosition('B'));
     $this->assertEquals(3, $compositeOuter->fieldPosition('D'));
     $this->assertEquals(0, $compositeInner->fieldPosition('C1'));
     $this->assertEquals(1, $compositeInner->fieldPosition('C2'));
     $compositeOuter->insertBefore('B', new TextField('AB'));
     $this->assertEquals(0, $compositeOuter->fieldPosition('A'));
     $this->assertEquals(1, $compositeOuter->fieldPosition('AB'));
     $this->assertEquals(2, $compositeOuter->fieldPosition('B'));
 }