Making travis to test nodejs app

Tra... what?

May be you have noticed .travis.yml file in some of open source GitHub repos. Travis tool - is a CI tool for github. CI - means continuous integration, which in turn - means that after every change of code some checks will be run automatically. It can be unit test, can be code standard checks (like lint) or whatever you want to be checked.

My Situation

In my case - In our company we have some nodejs + typescript + mongo application which has mocha/chai unit tests (pretty common stack nowdays).
Here is basic travis configuration which runs tslint and unit tests

language: node_js
node_js:
  - "9"
sudo: required
dist: trusty
addons:
  chrome: stable
cache:
  directories:
  - $HOME/.npm
env:
  matrix:
    - MONGODB=3.6.6
install:
  - wget http://fastdl.mongodb.org/linux/mongodb-linux-x86_64-${MONGODB}.tgz
  - tar xzf mongodb-linux-x86_64-${MONGODB}.tgz
  - ${PWD}/mongodb-linux-x86_64-${MONGODB}/bin/mongod --version
  - npm install
before_script:
  - mkdir ${PWD}/mongodb-linux-x86_64-${MONGODB}/data
  - ${PWD}/mongodb-linux-x86_64-${MONGODB}/bin/mongod --dbpath ${PWD}/mongodb-linux-x86_64-${MONGODB}/data --logpath ${PWD}/mongodb-linux-x86_64-${MONGODB}/mongodb.log --fork
script:
  # run build script specified in package.json
  - npm run tslint
  - npm run test
  - npm run build

Notice that mongo can be installed at testing machine travis creates each time when tests are run. Mongo is needed for run unit tests