web-platform-tests/wpt

Add coverage for discarded browsing contexts

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#3,310 opened on Jul 19, 2016

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good first issuehtmltype:missing-coverage

Description

In https://github.com/whatwg/html/pull/1539 and linked issues we are having a voyage of discovery over what happens when you remove an iframe from a document. The browsing context is "discarded," but what does that imply?

Browsers vary wildly in exactly how they implement this. Most seem to agree on things "going away" in some fashion. But sometimes they return undefined instead of null, and Edge likes to give a strange "Object expected" error.

After that PR, the following are some good test cases I think could be added, per new spec. Assume iframeWindow and iframeDocument are saved references to an iframe's contentWindow and contentDocument, saved before removing the iframe.

  • iframeWindow.{top, parent, frameElement} should be null
  • iframeWindow.{window, self, frames} should be iframeWindow
  • iframeWindow.document should be iframeDocument
  • iframeDocument.defaultView should be null
  • iframeDocument.location should be null

There are also a series of possible tests around ensuring that such documents do not have a browsing context:

  • Inserting a stylesheet into iframeDocument should not cause fetches
  • Inserting an image into iframeDocument should not cause fetches
  • Inserting a script into iframeDocument should not cause script execution

Here are some live dom viewers that can give a start:

Contributor guide

Tech stack
javascripthtmlcss
Domain
frontendtesting
Issue type
test
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
HTML iframesJavaScript fundamentalsWeb platform tests structure
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60
Research direction
Review the specification changes in whatwg/html#1539 and the linked issues to understand the expected behavior. Use the provided live DOM viewers to verify browser behavior. Implement the test cases listed in the issue description, ensuring coverage for all the mentioned scenarios. Check existing tests in the wpt repository for similar patterns.