how to best set up jest with reactjs

I have the following structure and i cannot sem to figure out how to best set this up. the facebook jest github page has them under folder name __test__ i have seen some people have it under root/tests and then you have unit and integration tests etc..

this is my folder structure

app
build
composer.json
composer.lock
config
dbconfig.js
docs
features
gitpull.sh
logs
node_modules
package.json
package-lock.json
phpunit.xml
postcss.config.js
README.md
schema
scripts
src
tests
utils
vendor
webpack.config.js

• I have my react application under app
• php code which is the restful api under src.
• phpunit tests under tests.
• html serverd under docs.
• vendor holds php libraries from composer