[browser][CoreCLR] Track remaining WBT coverage gaps #135046

Track the remaining browser-WASM Wasm.Build.Tests scenarios applicable to CoreCLR, using Mono coverage as a reference. This covers application build/publish behavior, not the separate runtime and libraries test suites.

CoreCLR is WebCIL-only by design. No-WebCIL lanes or smoke tests are out of scope. Mono-specific AOT, profiler, and threading cases are not automatic CoreCLR parity targets.

Progress and baseline

• #135018, merged on October 1, enables 23 methods / 54 additional CoreCLR CI-selected rows per OS while preserving Mono's existing inputs. All 84 local CoreCLR rows passed.
• Verified the newly enabled rows in the first completed scheduled main build containing [browser][CoreCLR] Enable non-AOT WBT relinking and rebuild coverage #135018: build 1620135, source commit c873bfd8, contains merge commit beb346ac. The selected WBT jobs succeeded on Linux and Windows.
• Uploaded xUnit XML contains the exact +54 workload-row increase per OS expected from [browser][CoreCLR] Enable non-AOT WBT relinking and rebuild coverage #135018: 216 -> 270, with 270 passed, 0 failed, and 0 skipped on both Linux and Windows. Across all CoreCLR WBT groups, each OS ran 406 tests from 48 uploaded XML files; all 406 passed, and all 52 Helix work items passed.

The post-merge counts below come from authoritative uploaded xUnit XML. The separate four-case no-workload increase is from #134618: three PublishRunAllPagesComposite rows and CompositeRequiresWebcil, all passing on both OSes. No other WBT source or CoreCLR job-list changes landed between the pre-merge and post-merge source commits, so the workload delta isolates #135018's 54 rows.

Linux and Windows have the same totals. The Mono column remains the September 29 WebCIL reference and was not remeasured in build 1620135. These totals include runtime-specific cases and are not a count of missing CoreCLR tests. Mono's no-WebCIL repetitions are excluded from the comparison. Although the parent build failed elsewhere, both selected CoreCLR WBT jobs and all of their Helix/XML results were green.

Remaining test work

• New assembly during incremental publish: fix the trimmed-closure asset-selection bug, then enable NativeRebuildTests.ReferenceNewAssemblyRebuildTest.ReferenceNewAssembly. The reproduced CoreCLR failure leaves the newly required System.Text.RegularExpressions.dll in linker output but omits it from WebCIL/published assets and boot configuration. A separate bug report is drafted; the test remains excluded from [browser][CoreCLR] Enable non-AOT WBT relinking and rebuild coverage #135018.
• Large-heap interop: revalidate MemoryTests.AllocateLargeHeapThenRepeatedlyInterop after the startup fix in [browser] Fix Debug-only startup failures: stack-first assert, incoming Module API, preRun function form #134527. Verify native relinking and allocations above 2 GB before removing its Mono gate.
• Undefined native symbols: recheck Templates.NativeBuildTests.BuildWithUndefinedNativeSymbol against CoreCLR's WasmAllowUndefinedSymbols behavior; resolve any contract mismatch before enabling it.
• Invariant/native-build conflict: port NativeRebuildTests.NoopNativeRebuildTest.NativeRelinkFailsWithInvariant to the CoreCLR diagnostic contract without requiring Mono AOT tooling.
• Auto-layout diagnostics: recheck PInvokeTableGeneratorTests.UnmanagedStructsAreConsideredBlittableFromDifferentAssembly_WithAutoLayout against the current generator and resolve its differing error expectations.
• Windows path handling: run NativeBuildTests.NativeBuildWithSpecialCharsInTempPath on CoreCLR/Windows and enable it if the command-line quoting behavior passes.
• Accurate compilation-mode coverage: correct misleading AOT-labeled cases, including Blazor.SimpleRunTests.BlazorPublishRunTest, whose aot argument is not forwarded to publish. Additional CoreCLR precompiled-mode cases should explicitly request PublishReadyToRun and verify its output; do not add duplicate rows merely because RunAOTCompilation=true is accepted.

Related open issues

These issues were open when checked on October 1. Keep implementation details in the existing issues and record the resulting WBT coverage here.

• [browser][CoreCLR] Match Mono NativeFileReference linker input support #134119 - Cover the supported CoreCLR NativeFileReference inputs and ensure P/Invoke module discovery matches actual linker inputs.
• [wasm][coreclr] Call-helper generation fails when the bundle contains an assembly deployed under a different file name #134915 - Add coverage for relinking an assembly deployed under a different filename. The filed repro is on WASI; first verify the browser path that uses the same call-helper generator.
• [browser][wbt] Re-enable HotReload in Wasm.Build.Tests #118442 - Restore WBT Hot Reload coverage once its SDK/Blazor prerequisites are satisfied.
• [wasm] Run Wasm.Build.Tests across .NET versions #110049 - Exercise supported SDK/workload/target-framework combinations across .NET versions.
• [browser] Move workload build from mono subsets to coreclr #132699 and [browser][coreclr] Strip workload content #134074 - Keep WBT setup and compatibility coverage working as CoreCLR is decoupled from Mono-produced workloads and workload contents are reorganized.
• [coreclr] Load PDBs for lazy-loaded assemblies #124898, [coreclr] CoreCLR does not load correct satellite resources #124901, and [coreclr] appsettings.json is Not Bundled in CoreCLR WASM #124895 - Revalidate the historical lazy-PDB, satellite-resource, and appsettings reports against current CoreCLR WebCIL behavior. Corresponding tests already execute successfully in the baseline; narrow or close stale reports rather than treating their open state as proof of missing coverage.

Acceptance criteria

• Each remaining applicable exclusion is either enabled with a regression test or linked to a concrete blocker.
• Newly enabled cases appear in generated workload selection and pass on the required platforms; existing Mono inputs and assertions are preserved.
• Updated Linux/Windows counts come from uploaded xUnit XML and distinguish executed cases, skips, and intentionally runtime-specific coverage.
• Relinking and R2R/AOT claims are supported by actual build outputs or compiler invocations, not test names or flag values alone.