Testing

xUnit throughout, one test project per source project, all under src/Tests/. ImplicitUsings is on and there is a global using Xunit, so test files need no using block for the framework.

Running tests

dotnet test src/Tests/InternalsViewer.Internals.Tests -p:Platform=x64

InternalsViewer.UI.App.Tests targets net10.0-windows and references the app project, so it needs the MSIX opt-out as well — without it the reference build runs the app's packaging step, which fails on most machines:

dotnet test src/Tests/InternalsViewer.UI.App.Tests -p:Platform=x64 -p:EnableMsixTooling=false

A single class or method:

dotnet test src/Tests/InternalsViewer.Query.Tests --filter "FullyQualifiedName~XmlEventParserTests"

dotnet test src/Tests/InternalsViewer.Query.Tests --filter "FullyQualifiedName~XmlEventParserTests.Parses_File_Event"

Do not run the whole suite after a mechanical change such as a rename or a namespace move — build to confirm it compiles, batch the remaining work, and run the suite once at the end.

Test projects

Project	Covers
InternalsViewer.Internals.Tests	Storage engine internals. Split into UnitTests/ and IntegrationTests/, with shared helpers in Helpers/
InternalsViewer.Execution.Tests	Iterator/join integration plus access-path units. Links TestServiceHost, RequiresFileFact and TestDatabase.mdf from Internals.Tests rather than duplicating them
InternalsViewer.Query.Tests	Event parsing, plan parsing, callstack projection
InternalsViewer.Connection.BackupFile.Tests	Backup file reading. Has its own RequiresFileFact/RequiresFileTheory
InternalsViewer.UI.App.Tests	Extracted UI logic plus headless SkiaSharp pixel tests that render into an SKBitmap
InternalsViewer.Internals.Tests.VerificationTool	Console tool, not a test project

Conventions

• Method names are Verb_Describes_Behaviour — Parses_File_Event, Can_Run_Simple_Query.
• Test folders and namespaces mirror the source project's folders, so a test for Events\Locks\LockGrouper lives in Events\Locks. InternalsViewer.Internals.Tests, InternalsViewer.Execution.Tests and InternalsViewer.Query.Tests keep UnitTests\ and IntegrationTests\ roots with the mirror beneath each. A test with no single subject type, such as a whole-backup read or a columnstore probe, sits at the root of its project or split, or in the area folder.
• The app project grants InternalsVisibleTo to its test project, so internal types are testable directly.

Tests that need external resources

Several tests are gated on resources that are not in the repo, and skip or fail rather than run:

• RequiresConnectionStringFact / RequiresConnectionStringTheory — skips unless the named connection string is present in user secrets. ConnectionStringHelper reads it from there, not from an appsettings file.
• RequiresFileFact — skips unless a data file is present. TestDatabase.mdf under IntegrationTests/Test Data/ is checked in; larger backup fixtures are not.
• QueryRunnerTests.Can_Run_Simple_Query is a genuine integration test: it needs a live SQL Server and symbols in C:\Symbols. Without a server it fails after roughly a 15-second timeout. That is environmental, not a regression. Invalid_Query_Gives_IsSuccess_False passes trivially in the same case.

Baselines — failures that are already on main

Check against these before treating a red test as something you broke:

• InternalsViewer.Internals.Tests — 14 unit failures on a clean main (DateTimeConverter locale sensitivity, allocation chain tests) plus 3 tests pinned to hardcoded values that have since changed. Baseline is roughly 600 of 617 passing with a lab server attached.
• InternalsViewer.UI.App.Tests — DockLayoutSerializer.Round_Trips_A_Split_Layout fails on clean main. Baseline 88 of 89.

A "test host process crashed" abort has been seen once after all tests had already passed, and did not reproduce on rerun.