Callback form of should chained off cy.window receives null when retried

Current behavior

My goal is to have a retriable check of a window property that my app exposes. To achieve that, I’m using the callback form of should.

The window object is correctly passed into the callback only for the first time. If the assertions fail and trigger a retry, the callback argument is null. (See the repro code)

Maybe I missed something, but I went through the docs and I don’t think this is expected behavior.

Desired behavior

The callback of should always receives the window object

Test code to reproduce

it('retries should on window object', () => {
    cy.window().should(win => {
      // this logs <window> on the first run, but null on the next
      cy.log('window =', win).then(() => {
        // failing to trigger a retry
        expect(true).to.equal(false)
      })
    })
})

Cypress Version

10.3.0

Other

No response

[BlueWinds]

Very interesting, thanks for the precise repro. I’m currently working in this area - how subjects are determined and how commands are retried - in relation to https://github.com/cypress-io/cypress/issues/7306.

The short version is that should is not really designed for this use case, and we don’t provide anything that is designed for this use case either. ^^;; I’m aiming to address that in my work. I’m going to assign myself here so I remember to follow up on this specific case.

A temporary workaround would be to ensure that you don’t have any cypress commands inside your should callback:

it.only('retries should on window object', () => {
      let count = 0
      cy.window().should(win => {
        count++
        if (count < 4) { throw new Error('foobar') }
        expect(win).to.haveOwnProperty('location')
      })
    })

This passes; it’s only when the should callback contains other cypress commands that cy gets confused over what the subject should be during retries.

[cypress-bot[bot]]

Released in 12.0.0.

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