Using docker for unit test

I run a MySQL container with --net=host option.

So now i can make unit test using:g:

self.db = MySQLdb.connect(host="127.0.0.1", user="XYZ", passwd="XYZ", db="TEST_DB")

The problem is when I try to dockerize my unit test, linking the container with my MySQL container, the 127.0.0.1 IP is not valid. I need to use the real ip for the MySql container, or use the DNS (/etc/hosts file).

So I need to alter the ip 127.0.0.1 for the name of the MySQL host.

I imagine that there is a better way to do this? I can, for example, alter the /etc/hosts file of my development enviroment.