How to test Slate JS behavior in Cypress

Question

How can I insert text in a Slate editor with Cypress? The Slate onChange handler doesn't seem to be called while typing with cy.type() or cy.clear().

Answer 1

The Cypress input commands (e.g. cy.type() and cy.clear()) work by dispatching input and change events - in the case of cy.type(), one per character. This mimics the behavior of a real browser as a user types on their keyboard and is enough to trigger the behavior of most application JavaScript.

However, Slate relies almost exclusively on the beforeinput event (see here https://docs.slatejs.org/concepts/xx-migrating#beforeinput) which is a new browser technology and an event which the Cypress input commands don’t simulate. Hopefully the Cypress team will update their input commands to dispatch the beforeinput event, but until they do I’ve created a couple of simple custom commands which will trigger Slate’s input event listeners and make it respond.

// commands.js
Cypress.Commands.add('getEditor', (selector) => {
  return cy.get(selector)
    .click();
});

Cypress.Commands.add('typeInSlate', { prevSubject: true }, (subject, text) => {
  return cy.wrap(subject)
    .then(subject => {
      subject[0].dispatchEvent(new InputEvent('beforeinput', { inputType: 'insertText', data: text }));
      return subject;
    })
});

Cypress.Commands.add('clearInSlate', { prevSubject: true }, (subject) => {
  return cy.wrap(subject)
    .then(subject => {
      subject[0].dispatchEvent(new InputEvent('beforeinput', { inputType: 'deleteHardLineBackward' }))
      return subject;
    })
});

// slateEditor.spec.js
cy.getEditor('[data-testid=slateEditor1] [contenteditable]')
    .typeInSlate('Some input text ');

cy.getEditor('[data-testid=slateEditor2] [contenteditable]')
    .clearInSlate()
    .typeInSlate('http://httpbin.org/status/409');

If you need to support other inputTypes, all of the inputTypes supported by Slate are listed in the source code for editable.tsx