API testing with jest

I am using NodeJS, Express and MongoDB for project. There are lot of API'S which I have to test. I have been told to use JEST to test them. I am referring to this site.Dev

The problem is I am working with MongoDB not SQL type DB. I don't understand how I'm going to use this in scripts.

"migrate": "npx sequelize-cli db:migrate",
"migrate:reset": "npx sequelize-cli db:migrate:undo:all && npm run migrate",
"pretest": "cross-env NODE_ENV=test npm run migrate:reset"