In Cypress, set a token in localStorage before test

Here's an example of adding a command cy.login() that you can use in any Cypress test, or put in a beforeEach hook.

Cypress.Commands.add('login', () => { 
  cy.request({
    method: 'POST',
    url: 'http://localhost:3000/api/users/login',
    body: {
      user: {
        email: '[email protected]',
        password: 'jakejake',
      }
    }
  })
  .then((resp) => {
    window.localStorage.setItem('jwt', resp.body.user.token)
  })

})

Then in your test:

beforeEach(() => {
  cy.login()
})

As an extra, you can also use the cypress-localstorage-commands package to persist localStorage between tests, so login request will be made only once:

In support/commands.js:

import "cypress-localstorage-commands";

Cypress.Commands.add('login', () => { 
  cy.request({
    method: 'POST',
    url: 'http://localhost:3000/api/users/login',
    body: {
      user: {
        email: '[email protected]',
        password: 'jakejake',
      }
    }
  })
  .its('body')
  .then(body => {
    cy.setLocalStorage("jwt", body.user.token);
  })
});

Then, in your tests:

before(() => {
  cy.login();
  cy.saveLocalStorage();
});

beforeEach(() => {
  cy.restoreLocalStorage();
});