[samuelgja]

Description

The @joint/react jest suite now takes its SVG mocks from the shared @joint/mock-svg package instead of its own copy in __mocks__/jest-setup.ts. The hand-rolled mocks (SVGPathElement, SVGAngle, ResizeObserver, createSVGMatrix / createSVGPoint / createSVGTransform, getBBox, getScreenCTM, getComputedTextLength, checkVisibility) are removed; only the DOMMatrix polyfill stays, since the package does not provide it.

The package mocks are closer to a browser without layout than the old ones, which leaked state between calls:

• The old createSVGMatrix() / createSVGPoint() returned one shared, mutable object, so V.transformPoint() returned its input and a matrix created with V.createSVGMatrix() kept the values written into it. The package returns a fresh all-zero point / matrix each time: every client point maps to the paper origin.
• The old checkVisibility() returned true for every element. The package reports an SVG node as rendered only when its getBBox() is non-empty, which the mock never is.
• The package installs its mocks once per test file, not before every test.

Test changes (same behaviour verified)

• __mocks__/jest-setup.ts: imports @joint/mock-svg; restores its ResizeObserver before every test, so the suites that install their own observer stay isolated, as with the per-test reinstall before.
• paper-button-interactions.test.tsx: the paper maps client points to local points one-to-one (it sits unscaled at the client origin). The drag test relied on the leaking matrix to move the element; with the identity mapping both cases (drag moves, press-and-release does not) are checked against a working pointer mapping.
• anchors.test.ts, extra-coverage.test.ts: magnets are treated as rendered (checkVisibility spied to true), so the DOM-measured fallbacks still measure the magnet instead of hitting the "not part of the render tree" branch.
• graph-store.test.ts: captures the ResizeObserver callback with jest.spyOn(); the package mock is a plain function, not a jest.fn().

@joint/mock-svg is a dev dependency with the workspace:~ range @joint/vitest-plugin-mock-svg uses. The changeset is empty: nothing in the published package changes.

Test plan

• yarn test in packages/joint-react on dev before the change: React 19 108 suites / 1170 tests, React 18 106 suites / 1129 tests, all passing.
• yarn test after the change: the same 108 / 1170 and 106 / 1129, all passing; typecheck, knip and jscpd pass.
• yarn lint: 0 errors (the 2 warnings are already on dev).
• Checked which tests reach the mocks whose results changed (point and matrix transforms, checkVisibility, transform.baseVal). Apart from the files above, they assert events, classes or that a value exists, not coordinates, so none of them passes on a value the old mocks produced by accident.
• Without the identity mapping, "moves the element when dragged" fails with the package mocks (the element stays at its position).

Context

Refs #3579.