chobie\Jira\Api\Authentication\Basic::getCredential PHP Method

    public function getCredential()
    {
        return base64_encode($this->_userId . ':' . $this->_password);
    }

 public function testBasicAuthentication()
 {
     $id = 'abc';
     $pass = '******';
     $basic = new Basic($id, $pass);
     $this->assertEquals($id, $basic->getId());
     $this->assertEquals($pass, $basic->getPassword());
     $this->assertEquals(base64_encode(sprintf('%s:%s', $id, $pass)), $basic->getCredential());
 }