Huawei release the Mate 7 in 2014 and right now they are working to get these devices updated to Marshmallow.

If you have the MT7-L09 or the MT7-TL10 model devices then you can send an email to mate7betatest1@huawei.com before the 22nd, proving them your IMEI number and current firmware version and you'll get a chance to try out Android 6.0