How can I execute code before all tests suite with Cypress?

Short answer: You can write your login command in a before hook within the supportFile (the file that is loaded automatically before your other spec files). This before hook will run before any of the code in your other test files.

Recommendations: That being said, this approach leaves little flexibility for variation in your individual test files that you may want in the future like:

• What if you want to seed the database differently for one test?
• What if you want to log in as a different user with different permissions?
• What if you need to do something in onBeforeLoad once?

I would recommend just having the login command in a before hook in each individual spec file.

I would also further recommend having your login command in a beforeEach hook to avoid sharing any state in between tests.