Cypress: Re-use auth token across multiple API tests

I have a Rest API which generates a token. This session token is used across multiple REST API’s as an authorization Bearer token. I used this as reference: https://github.com/cypress-io/cypress-example-recipes/blob/master/examples/logging-in__jwt/cypress/integration/spec.js

However, in that example, the function to generate token is embedded in the test. I tried to create a custom command for which should store locally but it is not being picked up by the test. Note that no return value is included in the custom command.

My code below under support/commands.js:

let identity
Cypress.Commands.add('postToken', () => {
    cy.request({
        method: 'POST',
        url: Cypress.env('api_identity_url'), //get from cypress.env.json
        form: true, //sets to application/x-www-form-urlencoded
        body: {
            grant_type: 'client_credentials',
            scope: 'xero_all-apis'
        },
        auth: {
            username: Cypress.env('api_identity_username'),
            password: Cypress.env('api_identity_password')
        }
    })
        .its('body')
        .then((response) => {
            identity = response
            window.localStorage.setItem('identity', JSON.stringify(identity))
            cy.log(identity.access_token)
        })
})

My test:

context('Check token details', () => {
  it('Check token', () => {
      cy.postToken()
      const bToken = window.localStorage.getItem('identity')
      cy.log(bToken)
  })
})

When I run the test, the log shows null value for ‘identity’. However, it shows the current value in the custom command where I placed cy.log(identity.access_token) I tried using cy.writeFile but I don’t think this is a clean method. There must be some way data can be passed between functions, and different classes.

Sample JSON format:

{
  "token": "<this is the value I would like to use for other API's authorisation bearer token>",
  "expires_in": 1200,
  "token_type": "Bearer"
}

Answer

You can use the cypress-localstorage-commands package to persist localStorage between tests.

In support/commands.js:

import "cypress-localstorage-commands";

Cypress.Commands.add('postToken', () => {
  cy.request({
    method: 'POST',
    url: Cypress.env('api_identity_url'), //get from cypress.env.json
    form: true, //sets to application/x-www-form-urlencoded
    body: {
      grant_type: 'client_credentials',
      scope: 'xero_all-apis'
    },
    auth: {
      username: Cypress.env('api_identity_username'),
      password: Cypress.env('api_identity_password')
    }
  })
  .its('body')
  .then(identity => {
    cy.setLocalStorage("identity_token", identity.token);
  });
});

Inside your tests:

describe("postToken", ()=> {
  before(() => {
    cy.postToken();
    cy.saveLocalStorage();
  });

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

  it("should exist identity in localStorage", () => {
    cy.getLocalStorage("identity_token").should("exist");
    cy.getLocalStorage("identity_token").then(token => {
      console.log("Identity token", token);
    });
  });

  it("should still exist identity in localStorage", () => {
    cy.getLocalStorage("identity_token").should("exist");
    cy.getLocalStorage("identity_token").then(token => {
      console.log("Identity token", token);
    });
  });
});