Nearly every headless UI test opened with the same four-line prologue
(resolve the shared MainWindow, show it, cast its DataContext, wait for the
assembly list), then repeated the corelib lookup, the EnsureLazyChildren +
Children.OfType<T>().Single() drill, the registry single-by-header lookups,
and the open-an-assembly-and-wait dance. The duplication made the intent of
each test hard to see and every signature tweak a suite-wide edit.
Collapse those into TestHarness (BootAsync, OpenAssemblyAsync, GetCommand,
GetEntry) and TreeNavigation extensions (FindCoreLib, GetChild<T>, Expand<T>),
then apply them across the suite. Net ~865 lines of boilerplate removed with
no change in behaviour; the full headless suite stays green.
Replaces the brittle root.GetVisualDescendants().OfType<T>().Single() / .First()
pattern with a new WaitForComponent<T>() extension that polls until the requested
control is in the visual tree, then returns it. Avalonia.Headless tests routinely
queried the visual tree before lazily-templated panes (DataGrid, dock content)
had materialised, surfacing as intermittent 'Sequence contains no elements'
failures across the suite.
Assisted-by: Claude:claude-opus-4-7:Claude Code
Each tree-expansion, selection change, command execution, async wait and
key/mouse injection inside an [AvaloniaTest] now carries a short imperative
comment on the line above (e.g. "// expand typeNode", "// select methodA",
"// wait for assemblies to load", "// execute aboutCmd"). The comments are
the same scaffolding the manual debug-with-screenshot workflow uses to
follow what's happening at each breakpoint, surfaced into the committed
source so the tests are readable without the breakpoint markers attached.
Assisted-by: Claude:claude-opus-4-7:Claude Code
AssemblyListPane attaches a ContextMenu to its TreeGrid at construction
time. The menu's Opening handler builds entries from the
ContextMenuEntryRegistry against a fresh TextViewContext (the live
selection + the grid as OriginalSource), and cancels Opening when no
entry would be visible so an empty popup never flashes up.
Assisted-by: Claude:claude-opus-4-7:Claude Code
Siegfried Pammer