tc39 / tc39/test262

Only use `phase: parse` for errors that happens while parsing the test entry point

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Description

https://github.com/tc39/test262/blob/main/CONTRIBUTING.md#negative

For a file with no dependencies, it's obvious that parse means that the error is thrown when calling ParseModule on its source code.

On the other hand, what happens when there are multiple files involved is less clear. Resolution of module dependencies is not defined in ECMA-262, but in HTML. Before the layering changes from 2022, there was a HostResolveImportedModule host hook that was responsible for loading/resolution of modules. There is also a ResolveExport AO, that might map to this "test262" resolution phase.

When running a test, there four possible phases:

  1. module = ParseModule(): parse the entry module
  2. module.LoadRequestedModules(): resolve, load and parse its dependencies
  3. module.Link(): resolve the various exported and imported bindings
  4. module.Evaluate(): executes the module and its dependencies

Before the 2022 layering changes, 1 and 2 where mixed together from an ECMA-262 point of view.

Looking at current tests, it seems like:

  • (1) is covered by phase: parse
  • (3) is covered by phase: resolution
  • (4) phase: evaluation

There is some confusion about (2):

Using phase: parse for tests thrown during (2) prevents most JavaScript parsers from successfully using test262 as a test suite for parsing tests, since those projects would just call ParseModule( test source ) and would not proceed to (2)/(3)/(4). On the other hand, using phase: resolution for it seems wrong, since module resolution happens outside of ecma262 and thus we are probably testing binding resolution.

I propose that we clarify the following:

  1. module = ParseModule() throws at phase: parse
  2. module.LoadRequestedModules() doesn't have a corresponding phase, and we will make sure to write no tests that throw at this point.
  3. module.Link() throws at phase: resolution
  4. module.Evaluate() throws at phase: evaluation

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with CONTRIBUTING.md#negative and review the cited tests, including test/language/import/import-assertions/json-invalid.js and test/language/module-code/source-phase-import/import-source-binding-name.js. Compare their phases with ParseModule(), LoadRequestedModules(), Link(), and Evaluate(), then clarify the guidance and determine which affected tests should be updated so phase metadata matches the intended boundaries.

Written by the indexing model from the issue text.

Assessment

Tech stack
javascript
Domain
documentation, testing-qa
Issue type
Documentation
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
42/100

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