How to Reuse a Login Across Tests
Intro
Most tests of a web application need a logged-in user. When each test logs in through the form first, the suite spends a few seconds per test on the same steps, and a problem in the login page fails every test, even the ones that test something else.
A Solution
Log in once, and reuse the session. After the login, the site keeps the session in a cookie (or in the local storage). The suite logs in through the form once, before the tests, and keeps the session cookie. Each test starts a fresh browser, adds the cookie, and goes straight to the page it tests, already logged in.
- Selenium, Selenide, WebdriverIO and Vibium read the session cookie after the login, and add it to the browser of each test. With Selenium, a cookie can only be added for the site of the current page, so the test opens the site first.
- Playwright saves the whole storage state of the browser context (cookies and local storage) with
storageState(), and starts the context of each test with it.
Each test still gets its own browser, so the tests stay independent. Keep one test that logs in through the form, so the login page is still covered. When the application has an API to log in, use it instead of the form (see tip 24).
Example
The examples use the login page of the-internet. After the login, the site
keeps the session in the rack.session cookie, and the secure area (/secure) shows the user name in #username.
Without the cookie, /secure sends the browser back to the login page.
The suite logs in once with tomsmith. Then two tests start already logged in: the first one opens the secure area
and checks the user name, and the second one logs out.
Expected Behavior
- A browser starts, logs in through the form, and the test keeps the session (the cookie or the storage state)
- That browser closes
- For each test, a fresh browser starts with the session, and opens the secure area without the form
- The first test checks the user name, and the second one logs out
- Each browser closes at the end of its test
Summary
Logging in once saves the login steps in every test, and keeps a problem in the login page in one test. Reuse the session for tests that run close together: sessions expire, so log in again at the start of each run.
Happy Testing!
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