Hola estoy intentando instalar phpunit pero no he podido miren lo que me sale,.

c:\xampp\php>pear channel-discover pear.phpunit.de
Discovering channel pear.phpunit.de over http:// failed with message: channel-a
d: Cannot open "http://pear.phpunit.de/channel.xml" (File http://pear.phpunit.d
:80/channel.xml not valid (received: HTTP/1.0 400 Bad Request
))
Trying to discover channel pear.phpunit.de over https:// instead
Adding Channel "pear.phpunit.de" succeeded
Discovery of channel "pear.phpunit.de" succeeded

c:\xampp\php>pear install phpunit/PHPUnit
No releases available for package "pear.phpunit.de/PHPUnit"
install failed

c:\xampp\php>