cypress-polly.js

// These are extracted from a project using pollyJS in Cypress
// They might not work, I've just copy/pastied what I thought was relevant and removed lines of codes specific to the project

const pollyConnect = (
  win,
  { mocks, mode, pollyName },
) => {
  console.log(
    `%cInit polly ${pollyName} for location ${win.location}`,
    'background: gray; color: white; padding: 5px',
  );

  const pollyBrowserFetch = new Polly(pollyName, {
    mode,
    adapters: ['fetch'],
    adapterOptions: {
      fetch: {
        context: win,
      },
    },
    persister: 'rest',
    logging: false,
    recordIfMissing: false,
    recordFailedRequests: true,
    timing: Cypress.config('pollyTiming') || Timing.fixed(0),
    matchRequestsBy: {
      /* configure what matters in your requests */
    },
  });

  Cypress.config('pollyBrowserFetch', pollyBrowserFetch);

  const { server } = pollyBrowserFetch;

  if (mocks) {
    server.host('my-host', () => {
      mocks(pollyBrowserFetch);
    }); 
  }
};

Cypress.Commands.add(
  'pollyVisit',
  (url, { mocks, ...options } = {}) => {
    const mode = Cypress.config('pollyMode') || 'replay';
    const pollyName = Cypress.config('pollyName');

    let pageLoadCount = 0;
    cy.on('window:before:load', (win) => {
      pageLoadCount++;

      if (pageLoadCount === 1) {
        pollyConnect(win, { mocks, mode, pollyName });
        return;
      }

      // If you want to support page reloads / changes you'll need to create new polly instances
      pollyReconnect(win, { pageLoadCount, mode, pollyName });
    });

    return cy.visit(url, options);
  },
);

beforeEach(function () {
  // In the beforeEach we generate a unique id/name for the test
  // pollyJS will use that name to store its recordings
  Cypress.config('pollyName', generateUniqueName(this.currentTest'));
});

afterEach(() => {
  // Commit mocks to disk
  // polly.stop() is a promise and prevents the test from finishing while pollyJS still has requests in flight
  cy.wrap(null, { log: false }).then(() => {
    const pollyBrowserFetch = Cypress.config('pollyBrowserFetch');
    return pollyBrowserFetch.stop()
  });
});

// In the test I set global pollymode to record or replay
 Cypress.config('pollyMode', 'replay');
// In the tests I use `pollyVisit` instead of `visit`
cy.pollyVisit('/my-page', {
  mocks: ({server}) => server.post('/my-manually-mocked-route').intercept((req, res) => res.status(200).json({ mocked: 'mock' }))
})