@dataProvider getInvalidDates
public function testInvalidDates($date) {
  $constraint = new Date(array(
    'message' => 'myMessage',
  ));
  $this->context
    ->expects($this
    ->once())
    ->method('addViolation')
    ->with('myMessage', array(
    '{{ value }}' => $date,
  ));
  $this->validator
    ->validate($date, $constraint);
}