How to properly deploy TEST and PROD with docker?

Question

Software Deployment

I have a web application that needs a database to work. How to properly deploy test and prod using docker?
nginx on the host, but then there are options:
1) 2 containers: TestAppAndDb + DropAppAndDb
2) 3 containers: TestApp + ProdApp + Db
3) 4 containers: TestApp + Db4TestApp + ProdApp + Db4ProdApp
Arguments are welcome, thanks.
PS: 1) and 3) are confusing with the need to raise 2 database instances