Integrate JUnit migration hardening from #1467 and #1468

[carstenartur]

Purpose

Integrate the coherent JUnit migration hardening developed in #1468 and #1467 without decomposing the working multi-file semantics into artificial micro-slices.

Integration strategy

• use Harden JUnit 4 migration on real Eclipse rule semantics #1468 as the primary JUnit 4, preset, Help and real-JDT-UI state;
• retain the stronger JUnit 3 constructor, suite, lifecycle and execution-order guarantees from Harden JUnit 3 migration on pinned real JDT tests with Oomph before/after QA #1467;
• preserve the real cleanup-preview work already merged through Add real Cleanup previews and atomic coordinated candidate UI #1464;
• remove temporary branch-repair mechanisms while retaining their semantic checks;
• accept behavior supported by focused regression tests and pinned real-corpus evidence.

Additional stabilization

• suppress the expected Equinox launcher error dialog without changing the cleanup exit-code contract;
• preserve each source file's original uniform line delimiter after project-wide cleanup;
• perform delimiter restoration through strict charset decoding/encoding and preserve UTF-8/UTF-16 byte-order marks, avoiding raw-byte corruption;
• add focused UTF-8, UTF-16LE and UTF-16BE regression tests.

Deliberately deferred follow-ups

• The unrelated functional-converter Map.computeIfAbsent conversion gap is documented by the disabled regression test and Functional converter: allow Map.computeIfAbsent on a different collection #1476 instead of extending this PR.
• The nondeterministic JUnit Help screenshot reproduction is tracked in Make the JUnit migration Help screenshot reproducible #1475 instead of blocking the implementation merge.

Merge policy

The PR is ready for an early squash merge once the repository's required Maven verification succeeds and GitHub reports it mergeable. Additional non-required evidence workflows may continue independently; they are not a reason to grow this PR further.

Refs #1367
Refs #1437
Supersedes the integration work from #1467 and #1468.

[Copilot]

Pull request overview

Integrates prior JUnit migration hardening work into a single coherent state, adding an explicit “best-effort” execution policy (with diagnostics + TODO scaffolds), tightening multi-file planning determinism, and introducing pinned upstream JDT UI QA workflows and evidence verification.

Changes:

• Add explicit Best-effort execution mode for JUnit migration (UI option, default off, preset-safe) with structured diagnostics + generated TODO scaffolds for unresolved gaps.
• Strengthen multi-file JUnit planning/application and add pinned upstream JDT UI corpus QA automation (contracts, verifiers, workflows, evidence artifacts).
• Add infrastructure hardening (encoded line delimiter preservation, headless cleanup application display ownership, additional diagnostics provider API).

Reviewed changes

Copilot reviewed 83 out of 93 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
sandbox_usage_view_test/src/org/sandbox/jdt/ui/helper/views/JUnitBestEffortCleanupDialogSWTBotTest.java	New SWTBot test asserting the best-effort option is visible and default-disabled in the real UI dialog.
sandbox_oomph/jdt-migration-qa.setup	New Oomph project setup to provision pinned Eclipse/JDT sources for migration QA.
sandbox_oomph/jdt-migration-qa.configuration.setup	New Oomph configuration (installation/workspace) for reproducible upstream migration QA.
sandbox_junit_cleanup/src/org/sandbox/jdt/internal/ui/preferences/cleanup/SaveActionCleanUpOptionsInitializer.java	Removes save-action defaults initializer (stop exposing migration as Save Action).
sandbox_junit_cleanup/src/org/sandbox/jdt/internal/ui/preferences/cleanup/SandboxCodeTabPage.java	Adds best-effort checkbox and wires it into JUnit preset/option mapping.
sandbox_junit_cleanup/src/org/sandbox/jdt/internal/ui/preferences/cleanup/DefaultCleanUpOptionsInitializer.java	Sets default for best-effort option to false.
sandbox_junit_cleanup/src/org/sandbox/jdt/internal/ui/preferences/cleanup/CleanUpMessages.properties	Adds localized label for best-effort option and updates preset label text.
sandbox_junit_cleanup/src/org/sandbox/jdt/internal/ui/preferences/cleanup/CleanUpMessages.java	Adds NLS field for best-effort label.
sandbox_junit_cleanup/src/org/sandbox/jdt/internal/ui/fix/ReportingJUnitCleanUpCore.java	New cleanup core wrapper that retains planning diagnostics JSON per project.
sandbox_junit_cleanup/src/org/sandbox/jdt/internal/ui/fix/JUnitCleanUpCore.java	Adds best-effort gap analysis, strict atomicity gating, TODO scaffolds, and import cleanup support.
sandbox_junit_cleanup/src/org/sandbox/jdt/internal/ui/fix/JUnitCleanUp.java	Switches wrapper to reporting core and exposes diagnostics provider API.
sandbox_junit_cleanup/src/org/sandbox/jdt/internal/corext/fix/multifile/JUnitMultiFilePlanner.java	Refines ExternalResource planning to avoid empty no-op subclass rewrites.
sandbox_junit_cleanup/src/org/sandbox/jdt/internal/corext/fix/JUnitMigrationOptions.java	New option key holder for migration execution policy (best-effort).
sandbox_junit_cleanup/src/org/sandbox/jdt/internal/corext/fix/JUnit4MigrationPresets.java	Makes “all supported” preset explicitly strict and ensures best-effort is never enabled by presets.
sandbox_junit_cleanup/src/org/sandbox/jdt/internal/corext/fix/helper/SuiteMethodJUnitPlugin.java	Extends JUnit 3 suite migration to handle legacy suite initializers via @BeforeSuite.
sandbox_junit_cleanup/src/org/sandbox/jdt/internal/corext/fix/helper/RunWithMigrationEligibility.java	New shared fail-closed runner eligibility assessment for strict/best-effort analysis.
sandbox_junit_cleanup/src/org/sandbox/jdt/internal/corext/fix/helper/RuleTestnameJUnitPlugin.java	Tightens TestName migration to binding-proven semantics and exact method-name mapping.
sandbox_junit_cleanup/src/org/sandbox/jdt/internal/corext/fix/helper/RuleImportCleanupSupport.java	New coordinator to safely remove shared org.junit.Rule import when all @Rule fields are migrated.
sandbox_junit_cleanup/src/org/sandbox/jdt/internal/corext/fix/helper/ParameterizedTestJUnitPlugin.java	Uses shared Parameterized eligibility contract and resolves parent type via ASTNodes.
sandbox_junit_cleanup/src/org/sandbox/jdt/internal/corext/fix/helper/ParameterizedMigrationEligibility.java	Broadens eligibility to accept explicit RunWith(value=...) syntax and improves diagnostics.
sandbox_junit_cleanup/src/org/sandbox/jdt/internal/corext/fix/helper/lib/JUnit3LegacyShape.java	New helper for fail-closed recognition/removal of redundant JUnit 3 legacy members.
sandbox_junit_cleanup/src/org/sandbox/jdt/internal/corext/fix/helper/lib/ExternalResourceRefactorer.java	Refines ExternalResource hierarchy adaptation and callback interface decisions.
sandbox_junit_cleanup/src/org/sandbox/jdt/internal/corext/fix/ClosedParameterizedTestJUnitPlugin.java	Expands patterns to match both @RunWith syntaxes.
sandbox_junit_cleanup/plugin.xml	Removes Save Action registration and initializer; keeps explicit cleanup configuration only.
sandbox_junit_cleanup_test/src/org/sandbox/jdt/internal/ui/preferences/cleanup/JUnitSaveActionRegistrationTest.java	New regression test ensuring migration isn’t registered as a save action.
sandbox_junit_cleanup_test/src/org/sandbox/jdt/internal/corext/fix/multifile/ParameterizedMigrationDiagnosticsTest.java	Updates diagnostic expectations for explicit @RunWith(value=...) acceptance.
sandbox_junit_cleanup_test/src/org/sandbox/jdt/internal/corext/fix/multifile/JUnitBestEffortSupportTest.java	New tests for best-effort gap analysis JSON + remediation contracts.
sandbox_junit_cleanup_test/src/org/sandbox/jdt/internal/corext/fix/multifile/JUnitBestEffortMigrationCleanUpTest.java	New end-to-end tests: strict quarantines whole CU; best-effort applies partial + TODO scaffold.
sandbox_junit_cleanup_test/src/org/sandbox/jdt/internal/corext/fix/JUnit4MigrationPresetsTest.java	Updates preset expectations to ensure strict “all supported” and best-effort forced off.
sandbox_junit_cleanup_test/src/org/eclipse/jdt/ui/tests/quickfix/Java8/RuleCleanupPrecedenceTest.java	Adjusts expected output to preserve migrated field visibility.
sandbox_junit_cleanup_test/src/org/eclipse/jdt/ui/tests/quickfix/Java8/ParameterizedMigrationContractTest.java	Updates contract to expect explicit @RunWith(value=...) migration.
sandbox_junit_cleanup_test/src/org/eclipse/jdt/ui/tests/quickfix/Java8/MultiFileExternalResourceNoOpSubclassTest.java	New regression coverage: leave callback-free subclass unchanged while migrating base + usage.
sandbox_junit_cleanup_test/src/org/eclipse/jdt/ui/tests/quickfix/Java8/MultiFileExternalResourceMigrationTest.java	Updates expected callback signatures (throws Exception) for ExternalResource migration.
sandbox_junit_cleanup_test/src/org/eclipse/jdt/ui/tests/quickfix/Java8/MultiFileExternalResourceLifecycleTest.java	Updates expected callback signatures (throws Exception) for lifecycle cases.
sandbox_junit_cleanup_test/src/org/eclipse/jdt/ui/tests/quickfix/Java8/MigrationRulesToExtensionsTest.java	Updates expected TestName/TempDir visibility and semantics, plus temp-path behaviors.
sandbox_junit_cleanup_test/src/org/eclipse/jdt/ui/tests/quickfix/Java8/MigrationJUnit3Test.java	Adds explicit JUnit 5 method order preservation expectations.
sandbox_junit_cleanup_test/src/org/eclipse/jdt/ui/tests/quickfix/Java8/MigrationJUnit3RealWorldShapesTest.java	New tests derived from pinned JDT Core shapes (constructors/suites/initializers).
sandbox_junit_cleanup_test/src/org/eclipse/jdt/ui/tests/quickfix/Java8/MigrationExceptionsTest.java	Adjusts expected message assertions to preserve substring semantics.
sandbox_junit_cleanup_test/src/org/eclipse/jdt/ui/tests/quickfix/Java8/MigrationCombinationsTest.java	Updates combined rule migration expectations (visibility + TestInfo semantics).
sandbox_junit_cleanup_test/src/org/eclipse/jdt/ui/tests/quickfix/Java8/JUnitMigrationCleanUpTest.java	Updates expected ExternalResource callbacks to throws Exception.
sandbox_junit_cleanup_test/src/org/eclipse/jdt/ui/tests/quickfix/Java8/JUnitCleanupCases.java	Updates fixture callback signatures and removes invalid super calls.
sandbox_junit_cleanup_test/src/org/eclipse/jdt/ui/tests/quickfix/Java8/JUnit3CleanupCases.java	Updates ordering expectations for JUnit 3 → Jupiter migration.
sandbox_junit_cleanup_help/toc.xml	Adds Help TOC entry for best-effort documentation page.
sandbox_junit_cleanup_help/html/usage.html	Expands usage guidance for strict vs best-effort workflows and screenshot QA.
sandbox_junit_cleanup_help/html/reference.html	Documents strict/best-effort safety model, evidence outputs, and limitations.
sandbox_junit_cleanup_help/html/index.html	Adds overview of strict vs best-effort modes and updates screenshot alt text.
sandbox_junit_cleanup_help/html/best-effort.html	New Help page documenting markers, diagnostics, and manual completion workflow.
sandbox_int_to_enum/src/org/sandbox/jdt/internal/corext/fix/helper/IntToEnumHelper.java	Refines stale/missing-binding recovery logic for invocation matching.
sandbox_common_core/src/test/java/org/sandbox/jdt/cleanup/io/EncodedLineDelimiterPreserverTest.java	New tests for delimiter + BOM preservation across encodings.
sandbox_common_core/src/main/java/org/sandbox/jdt/cleanup/multifile/api/IMultiFileCleanUpDiagnosticsProvider.java	New optional API to expose last planning diagnostics JSON for multi-file cleanups.
sandbox_common_core/src/main/java/org/sandbox/jdt/cleanup/io/EncodedLineDelimiterPreserver.java	New utility to preserve original delimiter/BOM while keeping encoding stable.
sandbox_common_core/META-INF/MANIFEST.MF	Exports new cleanup.io package.
sandbox_cleanup_application/src/org/sandbox/jdt/core/cleanupapp/HeadlessProjectWideCodeCleanupApplication.java	New headless wrapper owning SWT Display lifecycle to avoid cross-thread disposal deadlocks.
sandbox_cleanup_application/plugin.xml	Registers new headless application entry point.
sandbox_cleanup_application/META-INF/MANIFEST.MF	Adds dependency on sandbox_common_core for shared utilities/APIs.
qa/upstream-jdt/verify_jdt_ui_corpus.py	New verifier ensuring strict/best-effort evidence matches contract and changed-file inventories.
qa/upstream-jdt/verify_jdt_ui_contract.py	New contract self-test/validator (pins, profiles, runner markers, verifier self-tests).
qa/upstream-jdt/verify_corpus_result.py	Adds/updates corpus result verification for named real-corpus JDT sources.
qa/upstream-jdt/README.md	Documents reproducible upstream JDT QA setup and evidence expectations.
qa/upstream-jdt/pins.env	Adds pinned upstream reproducibility contract (repos/refs/commits).
qa/upstream-jdt/overlays/jdt-core-r4_40-jupiter.patch	Adds Jupiter API imports overlay for pinned upstream builds.
qa/upstream-jdt/junit4-to-jupiter.properties	Adds strict profile for pinned JDT UI JUnit 4 migration QA.
qa/upstream-jdt/junit4-to-jupiter-best-effort.properties	Adds best-effort profile for pinned JDT UI QA with scaffolding/diagnostics.
qa/upstream-jdt/junit3-to-jupiter.properties	Adds JUnit 3 strict profile for pinned JDT Core QA.
qa/upstream-jdt/jdt-ui-junit4-corpus.json	Adds pinned JDT UI corpus contract with strict quarantine + best-effort marker requirements.
qa/upstream-jdt/expected-test-mapping.json	Adds baseline test identity mapping contract (currently empty).
qa/upstream-jdt/expected-corpus.json	Adds JDT Core named corpus requirements for migration verification.
qa/upstream-jdt/compare_test_inventory.py	Adds baseline vs migrated JUnit XML inventory comparison tool.
.github/workflows/jdt-ui-junit4-strict-qa.yml	New CI workflow running pinned JDT UI strict before/after QA + whitespace regression checks.
.github/workflows/eclipse-help-screenshots.yml	Removes write permissions and auto-commit behavior; keeps reproducibility verification.

Suppressed comments (1)

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