/**
* Format date.
*
* @param string $format Format accepted by date(). When empty it's using the default format.
*
* @return string
*/
public function format($format = '')
{
if ($this->isHollow()) {
$format = $this->format;
} else {
$format = $format ?: $this->format;
}
return parent::format($format);
}
/**
* @covers ::format
*/
public function test_format_custom_format()
{
// When
$dt = new DateTime('1956-11-12');
// Then
$this->assertSame('1956:11:12', $dt->format('Y:m:d'));
}