Speed up the C# test suite (full run ~8m30s -> ~7m) (BL-16556)

[andrew-polk]

Ref: https://issues.bloomlibrary.org/youtrack/issue/BL-16556

Speeds up the C# test suite: full run ~8m30s → ~7m, and a run that skips network-dependent fixtures (--filter TestCategory!=Integration) finishes in ~3m25s. Every test still exercises the same real code paths as before.

• Share one off-screen page-checks browser across the epub and bloompub test fixtures via a new test hook, PublishHelper.ExternalPageChecksBrowserForTests. Each epub export / bloompub creation previously booted and tore down its own WebView2 environment (browser process + dedicated STA thread). The fixtures create one browser per fixture and clear the hook on teardown; the real browser-based visibility/font checks still run for every book. Production is unaffected (the hook is never set outside tests). Epub suite: 1m32s → 1m9s.
• Dispose the ZipFiles in BloomPubMakerTests.TestHtmlAfterCompression. The undisposed ZipFile kept each .bloompub locked, so each TempFile Dispose sat in RobustIO/RetryUtility sleep-retry loops (~80% of the fixture's wall time). Fixture: 1m41s → 19s.
• Fix BloomServerTests.CanGetActivityImage, which used RobustFile.Create to make its test image: that left the stream open (file locked) and the file empty (invalid PNG), sending the server's image pipeline into ~20s of PalasoImage.FromFileRobustly retries. It now writes a real small PNG and closes it. Test: 23s → <1s; fixture: 27s → 4s.
• Mark the four WebLibraryIntegration fixtures that talk to live web services (unit-test S3 buckets, bloomlibrary API, production site) with [Category("Integration")]. They still run by default; the category just makes their ~3.5 minutes of network tests skippable when a quick local iteration doesn't need them.
• Make the opt-in manual RAB build test check its whole toolchain up front (launcher, keytool, buildapp.bat on the PATH) and fail fast (~200ms) with an actionable message, instead of letting RAB churn for ~10s before failing with "'buildapp.bat' is not recognized".

🤖 Generated with Claude Code

Devin review

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This change is 

[greptile-apps]

Greptile Summary

This PR shaves ~1m30s off the full C# test suite (and ~5m off the filtered run) by eliminating redundant WebView2 startups, fixing file-lock-induced retry loops, and tagging slow network tests with [Category("Integration")]. All optimizations are test-only — production code is unchanged except for the addition of an internal test hook field that is never set outside of tests.

• Shared OffScreenBrowser per fixture: PublishHelper.ExternalPageChecksBrowserForTests lets epub and bloompub fixtures boot WebView2 once per fixture instead of once per export; teardown correctly clears the hook before disposing the browser, and ReleaseBrowser/Dispose leave the external browser alone.
• ZipFile disposal in BloomPubMakerTests: wrapping the ZipFile opens in using blocks eliminates the file-lock that was causing each TempFile.Dispose to spin in RobustIO retry loops, cutting the fixture from ~1m41s to ~19s.
• Real PNG in BloomServerTests.CanGetActivityImage: replacing RobustFile.Create (which left the file empty and the stream open) with a properly written and closed Bitmap stops the server's image pipeline from retrying for ~20 seconds on an invalid file.

Important Files Changed

Filename	Overview
src/BloomExe/Publish/PublishHelper.cs	Adds ExternalPageChecksBrowserForTests static test hook; ReleaseBrowser and Dispose correctly skip it, leaving ownership with the fixture.
src/BloomTests/Publish/BloomPub/BloomPubMakerTests.cs	Shares one browser across the fixture via the test hook and wraps ZipFiles in using blocks, fixing the file-lock retry-loop that dominated the fixture run time.
src/BloomTests/Publish/Epub/ExportEpubTestsBaseClass.cs	Shares one OffScreenBrowser per fixture via the test hook; setup/teardown are correctly balanced across the base class and all overriding subclasses.
src/BloomTests/Publish/Rab/RabRealBuildTests.cs	Adds up-front toolchain checks with actionable messages, making the opt-in test fail fast instead of after a confusing 10-second RAB run.
src/BloomTests/web/BloomServerTests.cs	Replaces empty-file RobustFile.Create with a real closed PNG, eliminating the server image-pipeline retry loop.
src/BloomTests/WebLibraryIntegration/BloomS3ClientTests.cs	Adds [Category(Integration)] to let callers skip live-network tests; no logic change.
src/BloomTests/WebLibraryIntegration/BloomS3StandardUpDownloadTests.cs	Adds [Category(Integration)]; no logic change.
src/BloomTests/WebLibraryIntegration/BookUploadAndDownloadTests.cs	Adds [Category(Integration)]; no logic change.
src/BloomTests/WebLibraryIntegration/ProblemBookUploaderTests.cs	Adds [Category(Integration)]; no logic change.

_{Reviews (1): Last reviewed commit: "Speed up the C# test suite (full run ~8m..." | Re-trigger Greptile}

[andrew-polk]

[Claude Fable 5] Consulted Devin on 2026-07-15 ~18:35 UTC up to commit 2063bee. Review completed with no findings (no bugs, no flags). Greptile also reviewed this commit and raised no issues.

[StephenMcConnel]

@StephenMcConnel reviewed 9 files and all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on andrew-polk).