public function testClearCustomHeaders()
{
$mail = new \r8\Mail($this->getTestTransport());
$mail->addCustomHeader('X-Test', 'value');
$mail->addCustomHeader('X-Other', 'value');
$this->assertTrue($mail->customHeaderExists('X-Test'));
$this->assertTrue($mail->customHeaderExists('X-Other'));
$this->assertSame($mail, $mail->clearCustomHeaders());
$this->assertEquals(array(), $mail->getCustomHeaders());
}