public function setHeaderAddsCharsetToMediaTypeIfNoneWasSpecifiedAndTypeIsText()
{
$message = $this->getAbstractMessageMock();
$message->setHeader('Content-Type', 'text/plain', true);
$this->assertEquals('text/plain; charset=UTF-8', $message->getHeader('Content-Type'));
$message->setHeader('Content-Type', 'text/plain', true);
$message->setCharset('Shift_JIS');
$this->assertEquals('text/plain; charset=Shift_JIS', $message->getHeader('Content-Type'));
$this->assertEquals('Shift_JIS', $message->getCharset());
$message->setHeader('Content-Type', 'image/jpeg', true);
$message->setCharset('Shift_JIS');
$this->assertEquals('image/jpeg', $message->getHeader('Content-Type'));
}