Cypress: Mixing cy.on()/cy.once() with a one-argument it() function causes test to hang

Created on 14 Sep 2018 · 3Comments · Source: cypress-io/cypress

Giving the lambda passed into the it() block a single argument will cause Cypress to pass a function in that must be called for the test to finish.

If you use the cy.on() command inside an it() block with a single-argument function, the test will hang when it reaches cy.on().

HTML:

<html>
  <body>
    <div id='covered' style='position:absolute;background:red;'>asdf</div>
    <div id='uncovered' style='position:absolute;background:blue;'>asdf</div>
  </body>
</html>

Test:

describe('Test', () => {
  it('Tests done()', done => {
    let shouldCallDone = false;

    cy.log('This log should happen.');

    cy.once('fail', (err) => {
      shouldCallDone = true;
    });

    cy.get('#covered').click({ timeout: 1000 });

    cy.log('This log should also happen, but it doesn\'t.');

    cy.get('html').then(() => {
      if (shouldCallDone)
        done();
      else
        throw "done() was never called."
    });
  });

  it('Tests cy.log', () => {
    cy.log('This log should happen too, but it also doesn\'t.');
  });
});