### [Read this on the main serverless docs site](https://serverless.com/framework/docs/guides/cicd/running-tests/) # Running Tests The Serverless Framework will automatically run tests for each deployment by running `npm test`. The tests must pass, return `0`, before the service is deployed. If the tests fail, then the service will not be deployed. The tests only run if a `test` script is present in the `package.json` file, like in the example below: ```json { "name": "my-serverless-project", "version": "1.0.0", "description": "", "main": "index.js", "scripts": { "test": "echo \"Error: no test specified\" && exit 1" }, "author": "", "license": "ISC" } ``` The tests will be skipped if the `npm test` command returns `Error: no test specified`. This is the response from `npm` if no `test` script is defined. It is also the default value of the `test` script when you initialize a new package.json via `npm init`. ## Running Node tests If you are using Node for your runtime, then all the dependencies will automatically be installed using `npm install` before tests are run. Update the `tests` script to run your node test suite (e.g. `mocha`). ## Running Python tests If you are using Python we recommend using the [serverless-python-requirements](https://github.com/UnitedIncome/serverless-python-requirements) plugin to install the dependencies from `requirements.txt`. If you are not using the serverless-python-requirements plugin, then you can install the requirements by adding the `postinstall` script to `package.json`. ```json { "name": "demo-python", "version": "1.0.0", "scripts": { "postinstall": "pip3 install -r requirements.txt", "test": "pytest" }, "devDependencies": { "serverless-python-requirements": "^5.0.1" } } ``` You must update the `test` script in `package.json` to run your Python tests suite (e.g. `pytest`).