fix incorrectly using Window.length as subject length

[kuceb]

fix #4396

[jennifer-shehane]

test?

[kuceb]

I added iframes to the test fixture as a test

[jennifer-shehane]

I see, we already have a test that calls cy.window().focus(), etc, but there's nothing guaranteeing that these iframes remain present in the DOM.html file, someone could delete them out if they 'think' there's no tests involving iframes in our suite.

Can you add an assertion in that test that's more explicit to assert the iframes are present and the cy.window().focus() doesn't fail? Looks good otherwise.

[kuceb]

@jennifer-shehane agreed, should be much better now

[jennifer-shehane]

Yay! Much better 💯

[jennifer-shehane]

Maybe a legitimate failure?

  1) src/cy/commands/screenshot #screenshot element capture passes through window:
     AssertionError: expected false to be true
      at getRet (http://localhost:3500/__cypress/runner/cypress_runner.js:71734:16)
      at tryCatcher (http://localhost:3500/__cypress/runner/cypress_runner.js:132224:23)
      at Function.Promise.attempt.Promise.try (http://localhost:3500/__cypress/runner/cypress_runner.js:129598:29)
      at Context.thenFn (http://localhost:3500/__cypress/runner/cypress_runner.js:71748:26)
      at Context.then (http://localhost:3500/__cypress/runner/cypress_runner.js:72014:21)
      at Context.<anonymous> (http://localhost:3500/__cypress/runner/cypress_runner.js:79052:21)
      at http://localhost:3500/__cypress/runner/cypress_runner.js:78757:33
      at tryCatcher (http://localhost:3500/__cypress/runner/cypress_runner.js:132224:23)
      at Promise._settlePromiseFromHandler (http://localhost:3500/__cypress/runner/cypress_runner.js:130242:31)
      at Promise._settlePromise (http://localhost:3500/__cypress/runner/cypress_runner.js:130299:18)
      at Promise._settlePromiseCtx (http://localhost:3500/__cypress/runner/cypress_runner.js:130336:10)
      at Async._drainQueue (http://localhost:3500/__cypress/runner/cypress_runner.js:127153:12)
      at Async._drainQueues (http://localhost:3500/__cypress/runner/cypress_runner.js:127158:10)
      at Async.drainQueues (http://localhost:3500/__cypress/runner/cypress_runner.js:127032:14)