# How to Run & Write Tests¶

## Running Tests¶

### Frontend¶

Run all tests:

npm test


Run single test:

npm test -- static/js/redux/__tests__/schema.test.js


### Backend¶

Run all tests:

python manage.py test


Run all tests for a single app:

python manage.py test timetable


Run single test suite:

python manage.py test timetable.tests.UrlsTest


Run single test case:

python manage.py test timetable.tests.UrlTest.test_urls_call_correct_views


Run tests without resetting db:

python manage.py test -k


Our current test runner will only run db setup if the tests you’re running touch the db.

## Writing Tests¶

### Unit Tests¶

Contributors are encouraged to write unit tests for changed or new code. By separating out logic into simple pure functions, you can isolate the behaviour you care about in your unit tests, and not worry about testing for side effects. Following the design principles outlined in the resources from the Learning The Stack section helps with this. For example, extracting all code that extract information from the state into selectors, which are pure functions that take the state (or some part of it) as input and output some data, will make it easy to test and change any state related behavior. Sometimes you may want to test behaviour that can’t be extracted into a pure function, or that touches external interfaces. There are a number of strategies you can use in these cases.

### Integration Tests¶

In the frontend, for testing the logic for rendering a component, look into snapshot tests. For testing async (thunk) action creators, our current tests create a store with desired initial state, dispatch the action, and then check that the action had the desired effect on the state. Backend requests are mocked using the nock library.

For testing views, we use django’s built in client to send requests to the backend. It’s also possible to use django’s request factory to create requests to provide directly as input to your views.

### End to End Tests¶

As the name implies, end to end tests test the entire app at once by simulating a semesterly user. When writing or changing end to end tests, it is recommended to familiarize yourself with the methods provided in SeleniumTestCase, which make it easy to perform certain actions on the app.