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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"@angular/build:unit-test (vitest): zoneless project fails to compile with \"Top-level await is not available\" when zone.js is a transitive dep","articleBody":"### Command\n\ntest\n\n### Is this a regression?\n\n- [x] Yes, this behavior used to work in the previous version\n\n### The previous version in which this bug was not present was\n\n21.2.13\n\n### Description\n\n## Description\n\nA zoneless Angular project (`provideZonelessChangeDetection()` in `main.ts`, no `zone.js` in the `polyfills` array) fails to compile its unit-test bundle with:\nX [ERROR] Top-level await is not available in the configured target environment (\"chrome145.0\", \"ios17.0\", \"safari17.0\" + 2 overrides)\n### Root cause\n\nIn `@angular/build/src/builders/unit-test/runners/vitest/build-options.js`, `getZoneTestingStrategy()` decides what to emit into the virtual `angular:test-bed-init` module:\n\n```js\nfunction getZoneTestingStrategy(buildOptions, projectSourceRoot) {\n  if (buildOptions.polyfills?.includes('zone.js/testing')) return 'none';\n  if (buildOptions.polyfills?.includes('zone.js'))         return 'static';\n  try {\n    projectRequire.resolve('zone.js');\n    return 'dynamic';                       // ← falls through to here for zoneless projects\n  } catch { return 'none'; }\n}\n```\nFor a zoneless app, polyfills correctly contains neither 'zone.js' nor 'zone.js/testing' — but zone.js is still resolvable on disk because it's an optional/peer dep of @angular/core (and several Angular test utilities like fakeAsync / tick still reference it). The strategy therefore resolves to 'dynamic', which emits this into the virtual module:\n```\nif (typeof Zone !== 'undefined') {\n  // 'zone.js/testing' is used to initialize the ZoneJS testing environment.\n  // It must be imported dynamically to avoid a static dependency on 'zone.js'.\n  await import('zone.js/testing');\n}\n```\n\nThe runtime guard typeof Zone !== 'undefined' would correctly skip the import on a zoneless app, but esbuild evaluates the top-level await at compile time and rejects the syntax — regardless of whether the branch can actually run. The build fails before the guard ever executes.\n\n### Expected\n\nA zoneless project should resolve the strategy to `'none'` and emit no zone-init code. The unit-test bundle should compile cleanly.\n\n### Actual\n\nStrategy resolves to `'dynamic'` because `zone.js` is transitively installed. The virtual `angular:test-bed-init` module contains a top-level `await`, which esbuild rejects against the configured browser targets — even though those targets (Chrome 145, iOS 17, Safari 17) actually do support TLA. The compile-time rejection appears to be tied to the output format guarantees rather than the targets themselves, so tightening browserslist does not help.\n\n### Minimal Reproduction\n\n1. Generate a zoneless Angular 22 app (or upgrade an existing zoneless app).\n2. Confirm main.ts uses provideZonelessChangeDetection() and polyfills in angular.json does not include 'zone.js' or 'zone.js/testing'.\n3. Configure test to use @angular/build:unit-test with the vitest runner.\n4. Run ng test.\n\n### Exception or Error\n\n```text\nTop-level await is not available\n```\n\n### Your Environment\n\n```text\n_                      _                 ____ _     ___\n    / \\   _ __   __ _ _   _| | __ _ _ __     / ___| |   |_ _|\n   / △ \\ | '_ \\ / _` | | | | |/ _` | '__|   | |   | |    | |\n  / ___ \\| | | | (_| | |_| | | (_| | |      | |___| |___ | |\n /_/   \\_\\_| |_|\\__, |\\__,_|_|\\__,_|_|       \\____|_____|___|\n                |___/\n    \n\nAngular CLI       : 22.0.0\nAngular           : 22.0.0\nNode.js           : 24.16.0\nPackage Manager   : npm 11.13.0\nOperating System  : win32 x64\n\n┌────────────────────────────────────┬───────────────────┬───────────────────┐\n│ Package                            │ Installed Version │ Requested Version │\n├────────────────────────────────────┼───────────────────┼───────────────────┤\n│ @angular-devkit/build-angular      │ 22.0.0            │ 22.0.0            │\n│ @angular/animations                │ 22.0.0            │ 22.0.0            │\n│ @angular/build                     │ 22.0.0            │ 22.0.0            │\n│ @angular/cdk                       │ 21.2.13           │ 21.2.13           │\n│ @angular/cli                       │ 22.0.0            │ 22.0.0            │\n│ @angular/common                    │ 22.0.0            │ 22.0.0            │\n│ @angular/compiler                  │ 22.0.0            │ 22.0.0            │\n│ @angular/compiler-cli              │ 22.0.0            │ 22.0.0            │\n│ @angular/core                      │ 22.0.0            │ 22.0.0            │\n│ @angular/forms                     │ 22.0.0            │ 22.0.0            │\n│ @angular/google-maps               │ 21.2.13           │ 21.2.13           │\n│ @angular/language-service          │ 22.0.0            │ 22.0.0            │\n│ @angular/material                  │ 21.2.13           │ 21.2.13           │\n│ @angular/material-date-fns-adapter │ 21.2.13           │ 21.2.13           │\n│ @angular/platform-browser          │ 22.0.0            │ 22.0.0            │\n│ @angular/platform-browser-dynamic  │ 22.0.0            │ 22.0.0            │\n│ @angular/platform-server           │ 22.0.0            │ 22.0.0            │\n│ @angular/router                    │ 22.0.0            │ 22.0.0            │\n│ @angular/service-worker            │ 22.0.0            │ 22.0.0            │\n│ @angular/ssr                       │ 22.0.0            │ 22.0.0            │\n│ rxjs                               │ 7.8.2             │ 7.8.2             │\n│ typescript                         │ 6.0.3             │ 6.0.3             │\n│ vitest                             │ 4.1.7             │ 4.1.7             │\n```\n\n### Anything else relevant?\n\n_No response_","author":{"url":"https://github.com/rLamonAC","@type":"Person","name":"rLamonAC"},"datePublished":"2026-06-08T07:45:54.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":2},"url":"https://github.com/33324/angular-cli/issues/33324"}