[browser] Make WASM framework asset CopyToOutputDirectory configurable by maraf · Pull Request #127285 · dotnet/runtime

maraf · 2026-04-22T16:00:42Z

Note

This PR was created with the assistance of GitHub Copilot.

Summary

Fixes the library-tests regression from #126407 tracked in #127257.

#126407 switched the WASM framework / webcil static web asset CopyToOutputDirectory from PreserveNewest to Never, which is correct for dotnet run (static web assets middleware serves files out of obj/fx/). But library tests in this repo run the app directly from bin/ without the middleware, so the framework files are missing and loading dotnet.*.js fails.

Changes

Microsoft.NET.Sdk.WebAssembly.Browser.targets: introduce a private MSBuild property _WasmFrameworkCopyToOutputDirectory (default Never) and route the three CopyToOutputDirectory values through it (Computed/webcil assets, Framework assets, and the post-UpdatePackageStaticWebAssets item update).
eng/testing/tests.browser.targets: set _WasmFrameworkCopyToOutputDirectory to PreserveNewest so library tests copy framework assets to the output directory as before.

Default behavior for regular dotnet run / Blazor WASM scenarios is unchanged.

During build, the WebAssembly SDK was copying all .wasm and .js framework assets to bin/wwwroot/_framework/ via CopyToOutputDirectory=PreserveNewest. This is unnecessary because dotnet run uses the static web assets middleware, which serves files directly from their obj/ locations using the manifest. Change CopyToOutputDirectory from PreserveNewest to Never for: - Webcil-converted assets (Computed static web assets) - Materialized framework assets (dotnet.js, dotnet.native.wasm, etc.) This eliminates ~178 file copies during build while preserving correct behavior for dotnet run (static web assets middleware) and publish (CopyToPublishDirectory was already Never). Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

With CopyToOutputDirectory=Never, framework assets are no longer copied to bin/wwwroot/_framework/ during build. They are served from obj/ locations via the static web assets middleware during dotnet run. Only assert bundle file layout for publish, where files are still physically copied to the output. Build-time tests that run the app (via dotnet run or xharness) still validate the app works correctly - they just don't check for files in bin/ that are intentionally no longer there. The Blazor-specific AssertBundle already had this guard WasmTemplateTestsBase path needed updating. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

With CopyToOutputDirectory=Never, framework files are no longer copied to bin/_framework/ during build. Update MultiClientHostedBuildAndPublish to assert framework files exist in obj/<config>/<tfm>/fx/<ProjectName>/ _framework/ for build, matching the materialization path used by UpdatePackageStaticWebAssets. Publish assertions remain unchanged. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Revert the IsPublish guard that skipped AssertWasmSdkBundle for builds. Instead, add AssertBuildBundle that validates framework files are in their correct obj/ subdirectories with CopyToOutputDirectory=Never: - dotnet.js (boot config) in obj/{config}/{tfm}/ - dotnet.runtime.js, maps, ICU in obj/{config}/{tfm}/fx/{name}/_framework/ - dotnet.native.* in fx/_framework/ (non-native) or wasm/for-build/ (native) - webcil assemblies in obj/{config}/{tfm}/webcil/ - framework files NOT in bin/_framework/ Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

- Gate webcil directory assertion on UseWebcil; when disabled, assemblies are materialized as DLLs in fx/_framework/ instead of webcil/. - Update SatelliteAssembliesFromPackageReference to check obj/ paths (webcil/{locale}/ or fx/{name}/_framework/{locale}/) instead of bin/_framework/ which is no longer populated. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

- Update targets comment to reflect CopyToOutputDirectory=Never behavior - Use named arguments for isUsingWorkloads/isNativeBuild parameters - Remove unused nativeDirLabel variable Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Restore dotnet.native.wasm check in the build branch of MultiClientHostedBuildAndPublish to match the publish branch, ensuring both clients have native assets materialized independently. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

…aded worker - Remove accidentally committed WasmAppHost symlink pointing to local Codespace build artifacts path - Add dotnet.native.worker.mjs validation in AssertBuildBundle for multi-threaded build scenarios to match publish-path coverage Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

With framework assets no longer copied to bin/_framework/ during build, update the three remaining failing tests to look for files in the obj subdirectories where they actually live: - Blazor BuildPublishTests.DefaultTemplate_WithResources_Publish: probe satellite assemblies under obj/{config}/{tfm}/webcil/{locale}/ (webcil) or obj/{config}/{tfm}/fx/{name}/_framework/{locale}/ (non-webcil) for the build-time assertion. - BuildPublishTests.BuildThenPublishWithAOT: stat framework files for the first build from obj/{config}/{tfm}/fx/{name}/_framework/ (JS, source maps) and obj/{config}/{tfm}/wasm/for-build/ (native outputs). Boot config is read from obj/{config}/{tfm}/dotnet.js via a new optional bootConfigDir parameter on GetFilesTable used by fingerprint resolution. - ModuleConfigTests.SymbolMapFileEmitted(isPublish=false): search for dotnet.native*.js.symbols in obj/wasm/for-build/ (native rebuild) and in obj/fx/*/_framework/ as a fallback. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Addresses review feedback: centralizes the obj/.../fx/<source-id>/_framework/ discovery logic in WasmSdkBasedProjectProvider.GetMaterializedFrameworkDir and uses it from AssertBuildBundle, BuildPublishTests and Blazor/MiscTests so the per-project fx subdir name is discovered instead of hardcoded. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

- Apply GetMaterializedFrameworkDir helper to the remaining three locations flagged by the review bot: Blazor/BuildPublishTests GetBuildSatelliteBaseDir, SatelliteLoadingTests, and ModuleConfigTests (the last still inlines the extra 'wasm/for-build' search path but deduplicates the fx-base Path.Combine). - Explain why dotnet.native.worker.mjs is not compared against the runtime pack in AssertBuildBundle (parity with AssertBundle's publish path comment). - Log when AssertWasmSdkBundle skips AssertBuildBundle because NonDefaultFrameworkDir is set, so the coverage gap is visible in test output. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

…n obj/fx With CopyToOutputDirectory=Never, the materialized framework dir under obj/{config}/{tfm}/fx/{source-id}/_framework/ contains dotnet.runtime.js under its canonical (non-fingerprinted) name during build. Fingerprinting is applied later when publishing to bin. GetFilesTable rewrites the entry from the boot config (which already reflects the publish layout), yielding a fingerprinted path that does not exist in obj/fx and causes CompareStat to report the file as missing. Override the dotnet.runtime.js entry to the unfingerprinted obj/fx path for the build-phase stat, mirroring the existing native-file override. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Run the server via 'dotnet run --no-build' and use Playwright's APIRequestContext to verify that each referenced client's framework files are served from the obj/ materialized directory at the /<client>/_framework/* base path. This guards the hosted scenario from PR dotnet#126407 review feedback (build-only, server statically serves client assets). Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

… asset copy Introduce a private MSBuild property _WasmFrameworkCopyToOutputDirectory that switches CopyToOutputDirectory between 'Never' (default) and 'PreserveNewest' for WASM framework/webcil static web assets in Microsoft.NET.Sdk.WebAssembly.Browser.targets. Enable it with 'PreserveNewest' in eng/testing/tests.browser.targets so library tests that run from bin/ without the static web assets middleware can still find the framework files. Fixes the regression from dotnet#126407 tracked in dotnet#127257. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

dotnet-policy-service · 2026-04-22T16:03:17Z

Tagging subscribers to 'arch-wasm': @lewing, @pavelsavara
See info in area-owners.md if you want to be subscribed.

maraf · 2026-04-22T16:03:20Z

Replaced by a cleaner branch off main.

Copilot

Pull request overview

This PR makes build-time copying of WASM framework/static web assets configurable (defaulting to not copying), while restoring the previous “copy to bin/” behavior for in-tree browser/library tests that run without the static web assets middleware.

Changes:

Introduces _WasmFrameworkCopyToOutputDirectory in the WASM Browser SDK targets and routes framework/webcil CopyToOutputDirectory behavior through it (default Never).
Sets _WasmFrameworkCopyToOutputDirectory=PreserveNewest in eng/testing/tests.browser.targets to fix in-tree test runs that execute directly from bin/.
Updates WASM build tests to validate the new default build layout (framework assets in obj/ materialization) and adjusts helpers to locate boot config appropriately.

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/mono/wasm/Wasm.Build.Tests/WasmSdkBasedProjectProvider.cs	Adds helpers/assertions for build-time (non-publish) asset layout under `obj/` and updates bundle assertions accordingly.
src/mono/wasm/Wasm.Build.Tests/Templates/WasmTemplateTestsBase.cs	Extends `GetFilesTable` wrapper to pass an optional boot-config directory.
src/mono/wasm/Wasm.Build.Tests/SatelliteLoadingTests.cs	Updates satellite assembly location checks to use `obj/` (webcil or materialized fx) instead of `bin/_framework`.
src/mono/wasm/Wasm.Build.Tests/ProjectProviderBase.cs	Adds `bootConfigDir` parameter to locate boot config when fingerprinting is enabled.
src/mono/wasm/Wasm.Build.Tests/ModuleConfigTests.cs	Adjusts symbol-map file lookup to search `obj/` build locations when build-time copying is disabled.
src/mono/wasm/Wasm.Build.Tests/BuildPublishTests.cs	Updates build-vs-publish file stat paths for the new default layout (but currently has a correctness issue—see PR comment).
src/mono/wasm/Wasm.Build.Tests/Blazor/MiscTests.cs	Updates hosted build assertions to check `obj/` materialized framework files and adds a runtime verification via `dotnet run --no-build` + Playwright fetch.
src/mono/wasm/Wasm.Build.Tests/Blazor/BuildPublishTests.cs	Adjusts resource DLL assertions to use build-time `obj/` locations.
src/mono/nuget/Microsoft.NET.Sdk.WebAssembly.Pack/build/Microsoft.NET.Sdk.WebAssembly.Browser.targets	Adds `_WasmFrameworkCopyToOutputDirectory` (default `Never`) and uses it for relevant framework/webcil static web assets.
eng/testing/tests.browser.targets	Forces framework assets to copy to output for in-tree browser tests by setting `_WasmFrameworkCopyToOutputDirectory=PreserveNewest` (should be conditional).

Copilot · 2026-04-22T16:09:24Z

+
+    <!-- Library tests run directly from bin/ without the static web assets middleware,
+         so copy framework files to the output directory. See https://github.com/dotnet/runtime/issues/127257. -->
+    <_WasmFrameworkCopyToOutputDirectory>PreserveNewest</_WasmFrameworkCopyToOutputDirectory>


This overrides _WasmFrameworkCopyToOutputDirectory unconditionally. To keep the file overrideable (and consistent with the surrounding properties in this PropertyGroup), consider setting it only when it’s not already set (e.g., add a Condition checking for empty).

Suggested change

<_WasmFrameworkCopyToOutputDirectory>PreserveNewest</_WasmFrameworkCopyToOutputDirectory>

<_WasmFrameworkCopyToOutputDirectory Condition="'$(_WasmFrameworkCopyToOutputDirectory)' == ''">PreserveNewest</_WasmFrameworkCopyToOutputDirectory>

Copilot · 2026-04-22T16:09:24Z

+            BuildPaths buildObjPaths = paths with { BinFrameworkDir = fxFrameworkDir };
            IDictionary<string, (string fullPath, bool unchanged)> pathsDict =
-                GetFilesTable(info.ProjectName, aot, paths, unchanged: false);
+                GetFilesTable(info.ProjectName, aot, buildObjPaths, unchanged: false, bootConfigDir: paths.ObjDir);
+
+            // dotnet.native.* are produced by the native rebuild into obj/wasm/for-build/ using


In this test, pathsDict is repurposed later for publish output paths, but then reused again for the “second build” StatFiles(pathsDict) / CompareStat(...) checks. After the publish step, pathsDict points at publish paths, so the second-build stat/compare is no longer validating build outputs. Consider keeping separate dictionaries for build vs publish (or recomputing pathsDict/BuildPaths for the second build) before calling StatFiles/CompareStat for the build phase.

maraf and others added 18 commits April 1, 2026 14:46

Merge branch 'main' into maraf/WasmSdkCopyToBin

fc681c1

Merge branch 'main' into maraf/WasmSdkCopyToBin

9e1c91a

Merge branch 'main' into maraf/WasmSdkCopyToBin

f830463

Merge branch 'main' into maraf/WasmSdkCopyToBin

07f446a

Copilot AI review requested due to automatic review settings April 22, 2026 16:00

maraf requested review from akoeplinger, ilonatommy and lewing as code owners April 22, 2026 16:00

github-actions Bot added the area-Build-mono label Apr 22, 2026

Copilot started reviewing on behalf of maraf April 22, 2026 16:01 View session

maraf added arch-wasm WebAssembly architecture os-browser Browser variant of arch-wasm labels Apr 22, 2026

maraf added this to the 11.0.0 milestone Apr 22, 2026

dotnet-policy-service Bot assigned maraf Apr 22, 2026

maraf closed this Apr 22, 2026

Copilot AI reviewed Apr 22, 2026

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[browser] Make WASM framework asset CopyToOutputDirectory configurable#127285

[browser] Make WASM framework asset CopyToOutputDirectory configurable#127285
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	<_WasmFrameworkCopyToOutputDirectory>PreserveNewest</_WasmFrameworkCopyToOutputDirectory>
	<_WasmFrameworkCopyToOutputDirectory Condition="'$(_WasmFrameworkCopyToOutputDirectory)' == ''">PreserveNewest</_WasmFrameworkCopyToOutputDirectory>

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maraf commented Apr 22, 2026

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