script.callFunction uses Realm.executeInGlobalWithBindings which will force cloning "this" and "arguments" before evaluating the function declaration: https://searchfox.org/mozilla-central/rev/25ec642ed33ca83f25e88ec0f9f27e8ad8a29e24/remote/webdriver-bidi/Realm.jsm#223-240

  executeInGlobalWithBindings(
    functionDeclaration,
    functionArguments,
    thisParameter
  ) {
    const expression = `(${functionDeclaration}).apply(__bidi_this, __bidi_args)`;

    return this.#globalObjectReference.executeInGlobalWithBindings(
      expression,
      {
        __bidi_args: this.#cloneAsDebuggerObject(functionArguments),
        __bidi_this: this.#cloneAsDebuggerObject(thisParameter),
      },
      {
        url: this.#window.document.baseURI,
      }
    );
  }

This is a problem whenever you are trying to use remote references (ie objects coming from this Realm, identified by a handle) because you should be able to use the original objects, and not a cloned version.

The deserialization algorithm should be responsible for cloning objects "when necessary" into the realm, but should preserve original objects if they are remote references.

An example fix can be found at https://phabricator.services.mozilla.com/D156201

A small example that fails because of this is

    remote_value = await bidi_session.script.evaluate(
        expression="window.test = {}; window.test",
        await_promise=False,
        result_ownership="root",
        target=ContextTarget(top_context["context"]),
    )
    result = await bidi_session.script.call_function(
        function_declaration="obj => obj === window.test",
        await_promise=False,
        arguments=[remote_value],
        target=ContextTarget(top_context["context"]),
    )
    assert result == {"type": "boolean", "value": True}

This should pass but since the remote_value gets cloned when we use call_function, the obj === window.test check will return false.

Depends on D155635

Unassigning until triage.

We will have to get this fixed for script.callFunctionOn so that the original object is used and not a clone.

Depends on D156201

Simple autoformatting to avoid unrelated changes in the next changeset

Depends on D156530

Add tests for deserialization of both this and arguments parameters, with various data structures (object, array, map, set) plus an additional test case nesting all
together.

Alternative to D156201

The severity field is not set for this bug.
:whimboo, could you have a look please?

For more information, please visit auto_nag documentation.

This is a M5 bug and should not block the enabling of the script commands by default.

(In reply to Web Platform Test Sync Bot (Matrix: #interop:mozilla.org) from comment #10)

Failed to create upstream wpt PR due to merge conflicts. This requires fixup
from a wpt sync admin.

This basically happened because bug 1779231 isn't on mozilla-central yet and it's open PR hasn't been merged. James could you please take a look here? Thanks.

https://hg.mozilla.org/mozilla-central/rev/83a729f1fffd
https://hg.mozilla.org/mozilla-central/rev/149ee65a5a38