[aaltat]

Fixes #5099

Summary

Add Init Script script=None * path=None arg=None scope=Test registers an init script on the active context: it runs before the page's own scripts in every page, frame and popup of that context. It is always context level; there is no page-level variant (ADR 0015).

Add Init Script                         (Python, Evaluation)
  path given → read the file in Python, send its source
  scope_owner(scope)                    Test fails outside a test, hint: scope=Suite
  rpc AddInitScript(content, arg)
    initScriptSource(content, arg)      (Node, init-script.ts)
      no arg → source as it is
      arg    → must compile as one expression → "(content)(arg)"
    context.addInitScript({content})    Disposable kept on the context
  InitScripts.added(context, script, scope)

end of test / suite (_end_test, _end_suite, before automatic closing)
  for each script of that scope
    rpc RemoveInitScript(context, script)  → disposable.dispose(), no-op if the context closed

Corrections to the issue body, found while implementing:

• With arg, the check is that the source is one expression, not one function expression. An expression that is not a function fails in the page, like any other error in the script.
• Errors in a script show up with Get Page Errors (Playwright pageerror), not in the console log.

Also: the glossary gets Init script, ADR 0015 records why it is context level with a scope, and the outdated comment in recorder.ts that said an init script cannot be removed is reworded (Recorder behaviour unchanged).

Evidence

• Before: no way to run JavaScript before the page's own scripts without a JS extension.
  After:
  • atest/test/05_JS_Tests/init_script.robot, 9 tests: the script runs before an inline page script, arg, path, popups, several scripts, a broken script does not fail the keyword and shows in Get Page Errors, error when arg is used with statements, error when both or neither of script/path are given, a Suite script reaches every test, and scope=Test fails in Suite Setup.
  • utest/test_init_script_scope.py runs its own two-test suite: a Test-scoped script does not reach the next test. With the removal at scope end disabled, this test fails.
  • utest/test_python_usage.py: on the Python path the script stays until its context closes; no open context fails.
  • Jest init-script.test.ts: arg wrapping, the one-expression check, a file ending in a line comment.
  • Locally after rebasing on main: inv utest 1765 passed, inv utest-node 406 passed, inv lint clean, full inv atest 1106 passed, 4 failed. The 4 failures are local to the maintainer's Mac and unrelated: three Firefox launch failures, and Wait For Response With OPTIONS Request, which needs Playwright 1.65 while the local wrapper install still has 1.64.1. The new tests also ran on 1.64.1 locally; CI runs them on 1.65.

Merge Danger

Door: two-way until released, one-way after: a released keyword is removed only through deprecation.

Blast Radius: small

Purely additive keyword. The only shared path touched is the end of each test and suite, which now also removes the init scripts of that scope; it does nothing when none were added.

🤖 Generated with Claude Code