fix(@angular/build): ignore side-effect annotations in unit test builds - #33917
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alan-agius4 merged 1 commit intoAug 25, 2026
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This pull request addresses an issue where statically-referenced barrel module bodies were incorrectly elided by esbuild in unit test builds when package.json had "sideEffects": false. This is resolved by setting buildOptions.ignoreAnnotations to true for unit test builds. A corresponding Vitest integration test has been added to prevent regressions. Feedback on the test suggests formatting the modified tsconfig.json with indentation for easier debugging.
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In libraries built with ng-packagr, `package.json` typically specifies `"sideEffects": false` so consumer applications can tree-shake unused code. However, when executing unit tests through `@angular/build:unit-test`, the test builder bundles workspace library source directly (via tsconfig paths). Because esbuild tree-shaking respects `"sideEffects": false` annotations in the enclosing `package.json`, bundling multiple spec entry points without splitting can cause esbuild to prune module bodies (such as component definitions) from multi-level `export *` barrel graphs while retaining namespace re-export accessors. At runtime, accessing the exported symbols evaluates to `undefined`, causing failures such as `TypeError: Cannot read properties of undefined (reading 'ɵcmp')`. Test bundles are executed locally in memory and never distributed over the wire, so side-effect annotations and pure call pruning are not required. Setting `ignoreAnnotations: true` when `disableCodeSplitting` is enabled ensures that statically reachable barrel exports in workspace code are retained without affecting production application or package builds. Closes angular#33910
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August 25, 2026 13:34
clydin
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In libraries built with ng-packagr, package.json typically specifies "sideEffects": false so consumer applications can tree-shake unused code. However, when executing unit tests through @angular/build:unit-test, the test builder bundles workspace library source directly (via tsconfig paths).
Because esbuild tree-shaking respects "sideEffects": false annotations in the enclosing package.json, bundling multiple spec entry points without splitting can cause esbuild to prune module bodies (such as component definitions) from multi-level export * barrel graphs while retaining namespace re-export accessors. At runtime, accessing the exported symbols evaluates to undefined, causing failures such as TypeError: Cannot read properties of undefined (reading 'ɵcmp').
Test bundles are executed locally in memory and never distributed over the wire, so side-effect annotations and pure call pruning are not required. Setting ignoreAnnotations: true when disableCodeSplitting is enabled ensures that statically reachable barrel exports in workspace code are retained without affecting production application or package builds.
Closes #33910