How to test SSH keys were added in Bitbucket or GitHub successfully?

How to test your SSH keys were added in Bitbucket or GitHub successfully?

BitBucket
ssh -T git@bitbucket.org
logged in as <user_name>

You can use git or hg to connect to Bitbucket. Shell access is disabled

GitHub
ssh -T git@github.com
Hi <user-name>! You've successfully authenticated, but GitHub does not provide shell access.