TypeError: Cannot read property 'length' of undefined when run test by cypress run

[sergeyblohin]

Current behavior:

I have testing site with shadow DOM.

it('test', () => {
  cy
    .get('div[class="oneAppNavContainer"]')
    .find('one-appnav')
    .find('span[title="          Config"]', {includeShadowDom: true})
    .contains('          Config');
});

It's code work correctly when I use cypress open.

But not work when I use cypress run.

TypeError: Cannot read property 'length' of undefined
    at superMatcher (https://example.com/__cypress/runner/cypress_runner.js:86701:17)
    at Sizzle.select (https://example.com/__cypress/runner/cypress_runner.js:86897:44)
    at Function.Sizzle [as find] (https://example.com/__cypress/runner/cypress_runner.js:85065:9)
    at jQuery.fn.init.find (https://example.com/__cypress/runner/cypress_runner.js:87096:11)
    at find (https://example.com/__cypress/runner/cypress_runner.js:153939:31)
    at getEl (https://example.com/__cypress/runner/cypress_runner.js:154030:18)
    at getElements (https://example.com/__cypress/runner/cypress_runner.js:154058:17)
    at Context.<anonymous> (https://example.com/__cypress/runner/cypress_runner.js:154082:14)
    at Context.<anonymous> (https://example.com/__cypress/runner/cypress_runner.js:163288:21)
    at https://example.com/__cypress/runner/cypress_runner.js:162724:15
    at tryCatcher (https://example.com/__cypress/runner/cypress_runner.js:10161:23)
    at Promise._settlePromiseFromHandler (https://example.com/__cypress/runner/cypress_runner.js:8096:31)
    at Promise._settlePromise (https://example.com/__cypress/runner/cypress_runner.js:8153:18)
    at Promise._settlePromiseCtx (https://example.com/__cypress/runner/cypress_runner.js:8190:10)
    at _drainQueueStep (https://example.com/__cypress/runner/cypress_runner.js:4872:12)

Desired behavior:

What I do wrong?

Versions

Cypress: 4.8.0
Chrome Canary 85

[jennifer-shehane]

Hey @sergeyblohin, thanks for opening an issue. Shadow DOM is experimental, so there could be an issue in your case.

In order to look into this, we'll need a fully reproducible example so that we can see where the error is throwing from and recreate it ourselves.

Please provide a repo with a failing test, or the application code required to run against this. Otherwise, we'll have to close the issue as there's no way forward to investigate.

[sergeyblohin]

@jennifer-shehane, thank you for responding.
I was able to find a site that exactly reproduces the defect I described.
I created a public repository: https://github.com/sergeyblohin/cypress-issue-7676
To play it, just do the following:

git clone git@github.com:sergeyblohin/cypress-issue-7676.git
cd cypress-issue-76
npm install

npm run cypress:open
# or
npm run cypress:run

cypress:open work correctly:
↓

cypress:run returns error:
↓

TypeError: Cannot read property 'length' of undefined

[jennifer-shehane]

@sergeyblohin Thanks for providing a repro!

Reproducible example

cypress.json

{
  "experimentalShadowDomSupport": true
}

spec.js

it('experimentalShadowDomSupport', () => {
    cy.visit('https://developer.salesforce.com/docs/component-library/overview/components');
    cy.get('componentreference-header[class="header dscVisible"]')
    .shadow()
    .find('componentreference-nav-bar[class="navigation"]')
    .should('exist');
})

cypress open

cypress run

This will error regardless of Electron or Chrome. The best way to debug the error is to pass cypress run --browser chrome --no-exit

  1) experimentalShadowDomSupport:
     TypeError: Cannot read property 'length' of undefined
      at superMatcher (https://developer.salesforce.com/__cypress/runner/cypress_runner.js:86701:17)
      at Sizzle.select (https://developer.salesforce.com/__cypress/runner/cypress_runner.js:86897:44)
      at Function.Sizzle [as find] (https://developer.salesforce.com/__cypress/runner/cypress_runner.js:85065:9)
      at jQuery.fn.init.find (https://developer.salesforce.com/__cypress/runner/cypress_runner.js:87096:11)
      at getEl (https://developer.salesforce.com/__cypress/runner/cypress_runner.js:154039:35)
      at getElements (https://developer.salesforce.com/__cypress/runner/cypress_runner.js:154058:17)
      at Context.<anonymous> (https://developer.salesforce.com/__cypress/runner/cypress_runner.js:154082:14)
      at Context.<anonymous> (https://developer.salesforce.com/__cypress/runner/cypress_runner.js:163288:21)
      at https://developer.salesforce.com/__cypress/runner/cypress_runner.js:162724:15
      at tryCatcher (https://developer.salesforce.com/__cypress/runner/cypress_runner.js:10161:23)
      at Promise._settlePromiseFromHandler (https://developer.salesforce.com/__cypress/runner/cypress_runner.js:8096:31)
      at Promise._settlePromise (https://developer.salesforce.com/__cypress/runner/cypress_runner.js:8153:18)
      at Promise._settlePromiseCtx (https://developer.salesforce.com/__cypress/runner/cypress_runner.js:8190:10)
      at _drainQueueStep (https://developer.salesforce.com/__cypress/runner/cypress_runner.js:4872:12)
      at _drainQueue (https://developer.salesforce.com/__cypress/runner/cypress_runner.js:4861:9)

[cypress-bot]

The code for this is done in cypress-io/cypress#7746, but has yet to be released.
We'll update this issue and reference the changelog when it's released.

[cypress-bot]

Released in 4.9.0.

This comment thread has been locked. If you are still experiencing this issue after upgrading to
Cypress v4.9.0, please open a new issue.