test(frontend): cover JointGraphWrapper highlighting, flags, zoom and coeditor paths

[mengw15]

What changes were proposed in this PR?

Extends the existing JointGraphWrapper spec to cover the remaining
unit-testable (non-rendering) methods
(frontend/src/app/workspace/service/workflow-graph/model/joint-graph-wrapper.ts).
The wrapper is built over a headless new joint.dia.Graph() with no
dia.Paper, matching the spec's existing setup. No production code was changed.

19 tests, grouped by the families the issue lists:

Highlighting — highlightLinks / unhighlightLinks,
highlightCommentBoxes / unhighlightCommentBoxes, highlightPorts /
unhighlightPorts, each asserted through the matching
getCurrentHighlighted*IDs getter and its highlight/unhighlight stream;
single-select (the default) dropping the previous highlight vs setMultiSelectMode(true)
keeping it; getCurrentHighlights / getCurrentHighlightedIDs aggregation
(ports are deliberately excluded from the latter); unhighlightElements
clearing all four families; and the group highlight streams, which operator
highlighting does not touch.

Flags — setReloadingWorkflow / getReloadingWorkflow and
setListenPositionChange / getListenPositionChange round-trips.

Zoom — setZoomProperty updating the ratio and emitting on the zoom stream,
isZoomRatioMin / isZoomRatioMax at the configured bounds, and
restoreDefaultZoomAndOffset resetting to INIT_ZOOM_VALUE while signalling a
paper-offset restore.

Cell layer / breakpoints / position — getCellLayer (z index, and the throw
for an unknown cell), getLinkIDsWithBreakpoint, and
getElementPositionChangeEvent reporting a moved element's old/new position.

Coeditor presence — addCoeditorOperatorHighlight /
deleteCoeditorOperatorHighlight, setCurrentEditing / removeCurrentEditing,
and setPropertyChanged / removePropertyChanged. These reach the canvas
through getMainJointPaper()?., so with no paper attached they must degrade to a
safe no-op; setCurrentEditing additionally returns a 300 ms interval, so the
test drives it under vi.useFakeTimers() and asserts removeCurrentEditing
clears it (real timers restored in a finally).

Two behaviours are asserted as the code actually behaves rather than as the issue
describes them, and are commented in the spec:

• setZoomProperty does not clamp — isZoomRatioMin/Max only report where
  the ratio sits relative to ZOOM_MINIMUM / ZOOM_MAXIMUM; clamping is the
  caller's job.
• the port streams emit unconditionally, so single-select's "clear the
  previous ports first" step surfaces as an extra empty batch on the unhighlight
  stream.

Out of scope per the issue (they need a real dia.Paper / geometry):
attachMainJointPaper / getMainJointPaper, autoLayoutJoint,
getElementPosition / setElementPosition / setAbsolutePosition,
restorePaperOffset.

Any related issues, documentation, discussions?

Closes #6825

How was this PR tested?

Extended unit tests, run locally in frontend/ (all green; the failure path was
verified by breaking an assertion to confirm the suite goes red):

ng test --watch=false --include src/app/workspace/service/workflow-graph/model/joint-graph-wrapper.spec.ts
# Test Files 1 passed (1) | Tests 47 passed (47)
prettier --write <spec>   # clean
eslint  <spec>            # clean

Was this PR authored or co-authored using generative AI tooling?

Generated-by: Claude Code (Opus 4.8 [1M context])

[Copilot]

Pull request overview

This PR expands the frontend unit test suite for JointGraphWrapper to cover additional non-rendering behaviors when used with a headless joint.dia.Graph() (no dia.Paper), aligning with the testing goals in issue #6825. No production code changes are included.

Changes:

• Added tests for highlighting/unhighlighting links, comment boxes, and ports (including single- vs multi-select behavior and aggregation getters).
• Added tests for workflow flags and zoom ratio behaviors (streams, bounds reporting, and default restore signaling).
• Added tests for cell layer lookup, element position-change events, and “no attached paper” coeditor paths.

---

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[github-actions]

Automated Reviewer Suggestions

Based on the git blame history of the changed files, we recommend the following reviewers:

• Contributors with relevant context: @bobbai00
  You can notify them by mentioning @bobbai00 in a comment.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 76.53%. Comparing base (d2ab966) to head (bfd265d).
⚠️ Report is 4 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #6830      +/-   ##
============================================
+ Coverage     76.48%   76.53%   +0.04%     
+ Complexity     3456     3452       -4     
============================================
  Files          1161     1161              
  Lines         45922    45919       -3     
  Branches       5101     5100       -1     
============================================
+ Hits          35125    35142      +17     
+ Misses         9256     9238      -18     
+ Partials       1541     1539       -2     

Flag	Coverage Δ		*Carryforward flag
access-control-service	70.00% <ø> (ø)		Carriedforward from f77b572
agent-service	76.76% <ø> (ø)		Carriedforward from f77b572
amber	67.33% <ø> (-0.01%)	⬇️	Carriedforward from f77b572
computing-unit-managing-service	20.49% <ø> (ø)		Carriedforward from f77b572
config-service	66.66% <ø> (ø)		Carriedforward from f77b572
file-service	67.21% <ø> (ø)		Carriedforward from f77b572
frontend	82.29% <ø> (+0.08%)	⬆️
notebook-migration-service	78.94% <ø> (ø)		Carriedforward from f77b572
pyamber	92.15% <ø> (+0.04%)	⬆️	Carriedforward from f77b572
workflow-compiling-service	55.14% <ø> (ø)		Carriedforward from f77b572

*This pull request uses carry forward flags. Click here to find out more.

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[aglinxinyuan]

LGTM!