cy.task passes null as default argument

[bahmutov]

Seems cy.task calls task with null value instead of undefined if the argument was NOT specified in the spec call

Cypress v3.7.0

Reproduction in https://github.com/cypress-io/cypress-test-tiny/tree/default-arg-in-task cypress-io/cypress-test-tiny@c899a79

Imaging we have a task and use default value for its argument like

module.exports = (on, config) => {
  // `on` is used to hook into various events Cypress emits
  // `config` is the resolved Cypress config
  on('task', {
    hello(name = 'world') {
      console.log('hello ', name)

      return null
    }
  })
}

When we call cy.task('hello') I expect the terminal to print hello world but it prints

ET /__cypress/tests?p=cypress/integration/spec.js-609 200 2.326 ms - 619
GET /__cypress/tests?p=cypress/support/index.js-949 200 1.387 ms - -
hello  null

Expected behavior

cy.task methods should respect default arguments (we should not be passing null values)

[cypress-bot]

The code for this is done in cypress-io/cypress#8600, but has yet to be released.
We'll update this issue and reference the changelog when it's released.

[cypress-bot]

Released in 5.3.0.

This comment thread has been locked. If you are still experiencing this issue after upgrading to
Cypress v5.3.0, please open a new issue.