swa-baseline-regeneration

name	swa-baseline-regeneration
description	Regenerate Static Web Assets test baselines. USE FOR: fixing "generated manifest should match the expected baseline" errors, updating baseline JSON files after legitimate build output changes, understanding the baseline comparison system.

SWA Baseline Regeneration

Baseline tests compare generated manifests against stored JSON files. When build output legitimately changes, baselines must be regenerated.

Error Signature

Expected collection to be empty because the generated manifest should match
the expected baseline. If the difference in baselines is expected, please
re-generate the baselines.

Baseline File Location

test/Microsoft.NET.Sdk.StaticWebAssets.Tests/StaticWebAssetsBaselines/

Two types per test:

Pattern	Content
{TestName}.Build.staticwebassets.json	Full build manifest (assets, endpoints, discovery patterns)
{TestName}.Build.files.json	Expected files on disk
{TestName}.Publish.staticwebassets.json	Publish manifest
{TestName}.Publish.files.json	Publish file list

Baselines use template variables for path portability:

• ${ProjectPath} — test project directory
• ${RestorePath} — NuGet cache path
• ${Tfm} — target framework moniker

How Baselines Work

Baselines are embedded resources compiled into the test DLL via Assembly.GetManifestResourceStream(). The comparison flow:

1. Test runs a full MSBuild build/publish against a test asset project
2. Loads the generated staticwebassets.build.json manifest from intermediate output
3. Calls AssertManifest(actual, LoadBuildManifest()) — templatizes actual paths (${ProjectPath}, etc.) and compares against the embedded baseline
4. Calls AssertBuildAssets(manifest, outputPath, intermediateOutputPath) — compares file lists

The templatization is done by StaticWebAssetsBaselineFactory.ToTemplate() in AspNetSdkBaselineTest.cs.

Regeneration Procedure

# 1. Build the test project to embed current baselines
.\artifacts\bin\redist\Debug\dotnet\dotnet.exe build `
  test\Microsoft.NET.Sdk.StaticWebAssets.Tests\Microsoft.NET.Sdk.StaticWebAssets.Tests.csproj `
  -c Debug --no-restore

# 2. Run affected tests with the regeneration flag
$env:ASPNETCORE_TEST_BASELINES = "true"
.\artifacts\bin\redist\Debug\dotnet\dotnet.exe test `
  artifacts\bin\Microsoft.NET.Sdk.StaticWebAssets.Tests\Debug\net11.0\Microsoft.NET.Sdk.StaticWebAssets.Tests.dll `
  --no-build --filter "FullyQualifiedName~AffectedTestClassName"

# 3. Clear the flag
Remove-Item Env:\ASPNETCORE_TEST_BASELINES

# 4. Rebuild the test project to embed the NEW baselines
.\artifacts\bin\redist\Debug\dotnet\dotnet.exe build `
  test\Microsoft.NET.Sdk.StaticWebAssets.Tests\Microsoft.NET.Sdk.StaticWebAssets.Tests.csproj `
  -c Debug --no-restore

# 5. Validate — run the same tests WITHOUT the flag
.\artifacts\bin\redist\Debug\dotnet\dotnet.exe test `
  artifacts\bin\Microsoft.NET.Sdk.StaticWebAssets.Tests\Debug\net11.0\Microsoft.NET.Sdk.StaticWebAssets.Tests.dll `
  --no-build --filter "FullyQualifiedName~AffectedTestClassName"

Critical: Why Steps 4 and 5 Are Mandatory

Step 2 writes new .json files to disk in StaticWebAssetsBaselines/, but they are embedded resources. The test DLL must be rebuilt (step 4) before the tests can read the updated baselines. Skipping step 4 means step 5 still compares against the old embedded baselines and will fail.

Alternative: Script-Based Regeneration

The repo includes src/RazorSdk/update-test-baselines.ps1:

# Regenerate:
dotnet test --project <TestProject> --no-build -c Release -v normal `
  --environment ASPNETCORE_TEST_BASELINES=true --filter "TestCategory=BaselineTest"

# Validate:
dotnet test --project <TestProject> --no-build -c Release -v normal `
  --filter "TestCategory=BaselineTest"

Test Classes That Use Baselines

Class	Test Asset
StaticWebAssetsAppWithPackagesIntegrationTest	RazorAppWithPackageAndP2PReference
JsModulesPackagesIntegrationTest	RazorAppWithPackageAndP2PReference
ScopedCssCompatibilityIntegrationTest	RazorAppWithPackageAndP2PReference
ScopedCssPackageReferences	RazorAppWithPackageAndP2PReference
LegacyStaticWebAssetsV1IntegrationTest	RazorAppWithPackageAndP2PReference
StaticWebAssetsIntegrationTest	Various