MoneyDataMapper example

$money = new Money(20.5, 'EUR');
        $factory = Forms::createFormFactoryBuilder()
            ->addExtensions([new ValidatorExtension(Validation::createValidator())])
            ->getFormFactory()
        ;

        $builder = $factory
            ->createBuilder(FormType::class, $money, ['invalid_message' => 'not the one to display'])
            ->add('amount', TextType::class)
            ->add('currency', CurrencyType::class)
        ;
        $builder->setDataMapper(new MoneyDataMapper());
        $form = $builder->getForm();

        $form->submit(['amount' => 'invalid_amount', 'currency' => 'USD']);

        $this->assertFalse($form->isValid());
        $this->assertNull($form->getData());
        $this->assertCount(1, $form->getErrors());
        $this->assertSame('Expected numeric value', $form->getTransformationFailure()->getMessage());
        $error = $form->getErrors()[0];
        $this->assertSame('Money amount should be numeric. "invalid_amount" is invalid.', $error->getMessage());
    }