fix(core): webview expect() keeps polling when the element is not in the DOM yet

[gmegidish]

Fixes #357

Problem

expect(webLocator).toBeVisible() on an element that is not in the DOM yet threw immediately instead of polling:

RpcError: webview evaluate failed: ... Cannot read properties of undefined (reading 'nodeType')

buildExpectEvaluate passed elements[0] straight into the injected expect(). Since Playwright 1.62 the injected matcher no longer guards against a missing element; playwright-core moved that handling server-side into Frame._expectInternal, which mobilewright does not run. The throw escaped _expect, so polling never started.

Fix

• The evaluate now resolves to null when a single-element matcher finds no element. Array matchers (to.have.count, *.array) still receive the empty list.
• New missingElementVerdict() in web-expect-matcher.ts decides that case, mirroring the no-element branch of Frame._expectInternal:
  • toBeHidden / toBeDetached pass.
  • not.toBeVisible / not.toBeAttached / not.toBeInViewport pass.
  • Everything else does not pass and is reported as a missing element, so polling continues until the timeout.
• _runInjectedExpect applies it, so both callers (Playwright's expect via _expect, and mobilewright's own expect) are covered.

Tests

• New unit tests for the verdict table, the evaluate guard, and _expect polling on a missing element
• npm test — 822 passed, 1 skipped
• npm run lint
• Extended the assertions-missing conformance spec (element added to the DOM after 1.5 s, toBeHidden, toBeVisible timing out as an ordinary failure)
• iOS simulator (iPhone 17, iOS 26.5, Playground): the spec fails with the nodeType error before the fix and passes after
• Same spec passes under real Playwright on Chromium

[coderabbitai]

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📥 Commits

Reviewing files that changed from the base of the PR and between 44a4c0b and 5e1dcc0.

📒 Files selected for processing (5)

• e2e/src/conformance/specs/assertions-missing.spec.ts
• packages/mobilewright-core/src/web-expect-matcher.test.ts
• packages/mobilewright-core/src/web-expect-matcher.ts
• packages/mobilewright-core/src/web-locator.test.ts
• packages/mobilewright-core/src/web-locator.ts

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Walkthrough

Matcher evaluation now returns a separate missing-element verdict for absent single elements while allowing empty results for array matchers. The locator uses that verdict when injected evaluation returns null. Tests cover missing-element assertion results, visibility polling, and ordinary assertion failures.

Priority: ➖ Normal

Severity of issue fixed: Medium

Merge Risk: ⚪ Minimal · up to 5e1dc

The change allows absent-element assertions to keep polling while preserving immediate success for appropriate missing-element checks. No concrete merge-blocking risk is established; Android validation remains unreported.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 71.43% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 7 functions across 5 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	Issue #357 requires a missing webview element to keep polling and to fail with a normal assertion error after timeout. The PR returns null for missing single-element matches, applies missingElementVer…
Out of Scope Changes check	✅ Passed	The changed matcher logic, locator integration, unit tests, and conformance tests all support issue #357. The additional handling for hidden, detached, negated visibility, attachment, and viewport ass…
Title check	✅ Passed	The title clearly and concisely describes the main change: webview expect() continues polling when the element is not yet in the DOM.
Description check	✅ Passed	The description directly explains the missing-element failure, the implementation, affected matchers, and validation results.

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