test(wdio-browserstack-service): guard a11y Browser type augmentation

Add a type-level test asserting the 5 accessibility methods
(startA11yScanning, stopA11yScanning, performScan, getAccessibilityResults,
getAccessibilityResultsSummary) are typed on WebdriverIO.Browser. These
declarations previously lived in an un-emitted ambient file and silently
never reached consumers; this test fails if the published augmentation
ever regresses again.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: harshit-browserstack

tests/typings/webdriverio/browserstackService.ts

@@ -0,0 +1,30 @@
+import { expectType } from 'tsd'
+import { browser } from '@wdio/globals'
+
+/**
+ * Regression guard for the @wdio/browserstack-service accessibility
+ * augmentation of WebdriverIO.Browser.
+ *
+ * These five methods are declared inside
+ *   declare global { namespace WebdriverIO { interface Browser { ... } } }
+ * in packages/wdio-browserstack-service/src/index.ts. They previously lived
+ * in an un-emitted ambient .d.ts file and silently never reached the published
+ * build/index.d.ts, so consumers lost the typings. This file pulls in the
+ * published @wdio/browserstack-service types (it is listed in this suite's
+ * tsconfig.json `types` array) and fails `test:typings:webdriverio` if any of
+ * the five methods ever stops being typed on WebdriverIO.Browser again.
+ */
+;(async () => {
+    expectType<() => Promise<Record<string, unknown>>>(browser.getAccessibilityResultsSummary)
+    expectType<() => Promise<Array<Record<string, unknown>>>>(browser.getAccessibilityResults)
+    expectType<() => Promise<Record<string, unknown> | undefined>>(browser.performScan)
+    expectType<() => Promise<void>>(browser.startA11yScanning)
+    expectType<() => Promise<void>>(browser.stopA11yScanning)
+
+    // also assert the call-site return types resolve as declared
+    expectType<Record<string, unknown>>(await browser.getAccessibilityResultsSummary())
+    expectType<Array<Record<string, unknown>>>(await browser.getAccessibilityResults())
+    expectType<Record<string, unknown> | undefined>(await browser.performScan())
+    expectType<void>(await browser.startA11yScanning())
+    expectType<void>(await browser.stopA11yScanning())
+})