Drive the editor's trees, panels and graph from tests, and fix the undo they caught (#128)

[matt-edmondson]

Follow-on to #139. The harness landed with the panel and tree files still excluded from coverage, because nothing could reach them: they draw plain ImGui.Buttons, and a test had no way to name one.

Addressing widgets by name

ktsu.ImGui.Probes closes that. It is a dependency-free package whose stated purpose is that an application, a widget library and a dialog library can each mark items without depending on one another — so an application marking its own widgets is what it is for, not a test-only hack. Marking costs nothing when no probe is installed, which is every run that is not a test.

The marks are deliberately few and central:

Where	Covers
One call in ButtonTree	Every row of every tree — classes, members, enums, enum values, data sources, code generators
One per + New button	The five add flows
One per context-menu entry	Rename and delete for every kind
A probe scope per member row	Keeps two rows' controls apart, the same job PushID does for ImGui itself

A test then writes App.Click("BtnUser") or App.Click("memberAge/Delete") and never states a coordinate.

37 new tests

• Tree navigation — clicking a class, member, enum, data source or code generator row selects the right thing, and clears the other selections.
• Adding — each + New button, the name it asks for, the element that results, and that a name already in use is refused rather than replacing what has it.
• Context menus — rename and delete for every kind, driven by right-clicking the row and choosing the entry.
• Member rows — reorder up and down, the ends of the list that cannot move further, delete, and that each is undoable.
• The class graph — drawn through WidgetHarness rather than the editor, because the tab bar comes from a widget library that does not record its tabs, so there is no name to click. Drawing the view directly reaches the same code and is what the editor's tab delegate does.

The bug they found

Undoing a delete put the element back at the end of its collection, because Restore* appends. Delete a member from the middle of a class, undo, and the class comes back reordered.

That is not cosmetic. The library documents member order as "part of the schema's meaning rather than a display concern" — it is the declaration order generated code uses, it round-trips through the file, and TryMoveMember exists precisely so users can control it. An undo that silently rewrites it is an edit of its own.

Fixed for members, classes and enums by remembering the index and moving the element back to it.

Data sources and code generators have the same bug and are deliberately not fixed here. Schema exposes an ordered set for classes and enums (ClassSet, EnumSet) and nothing equivalent for those two, so the editor has nothing to reposition them with. Fixing it means adding public API to a published package, which is your call rather than mine — the obvious shape is DataSourceSet / CodeGeneratorSet mirroring the two that exist. It is recorded in the roadmap's decisions, and the test that covers those deletes says so rather than asserting the current behaviour is right.

Coverage

The exclusion is now just SchemaEditor/Program.cs, which holds only Main — the third acceptance criterion of #128, "narrowed to what genuinely cannot be executed".

File	Before	After
ClassGraphView.cs	3.2%	80.3%
TreeClass.cs	excluded	92.6%
TreeDataSource.cs	excluded	90.8%
TreeCodeGenerator.cs	excluded	90.6%
ButtonTree.cs	excluded	86.7%
TreeEnum.cs	excluded	82.1%
SchemaEditor.Panels.cs	excluded	54.5%
CodeGeneratorPanel.cs	excluded	42.3%

Nothing in the editor is unmeasurable any more; what is left is a question of how much each panel is worth testing, not of whether it can be. New-code coverage measured locally at 95.6%, over the gate's 80%.

Verification

382 tests, 0 failures (299 library + 83 editor).

🤖 Generated with Claude Code

https://claude.ai/code/session_01Jc8o5zF3cmfCGjzWvQdGDE

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Generated by Claude Code

[sonarqubecloud]

Quality Gate passed

Issues
8 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud