fix(⚛️): build the Jest mock's ref handle once, and test Canvas under React Native Testing Library

[YevheniiKotyrlo]

Problem

The Jest mock's Canvas, which apps render in their own Jest tests, builds its ref handle on every render (useImperativeHandle without dependencies). A ref gets a new handle after each re-render, and a state setter used as the ref re-renders its owner until React stops with "Maximum update depth exceeded". Canvas itself builds its handle once since #532.

Nothing catches this: every spec under packages/webgpu/src/__tests__ goes through the e2e harness (jest.config.js gives the tree a globalSetup that waits for the example app), so no test renders a component under Jest. Canvas's layout size (#531) and its single handle (#532) have no device test either.

#525's two fixes reached main through #531 and #532; this carries what remained of it.

Solution

• The mock builds its handle once.
• jest.unit.config.js runs src/__tests__/unit with React Native's Jest preset and React Native Testing Library 14, which renders on test-renderer, React 19's replacement for the deprecated react-test-renderer. The e2e config skips that directory, and CI runs yarn test:unit in the build job beside the plugin's tests.
• The Tests screen gains a canvas laid out at 64 × 32 and drawn at half that size under a scale transform, and a re-render that resolves once a commit has rendered it, for Canvas.spec.ts. setup.ts's isNativeApp() replaces the specs' inline platform checks.

Tests

• unit/mock.test.tsx: the mock's handle survives re-renders, a state setter as its ref settles, it answers -1 and null and throws from getNativeSurface(), and it keeps its own props off the View it renders. Without the fix, the first two fail: five ref calls instead of one, and "Maximum update depth exceeded".
• unit/Canvas.test.tsx, with a stand-in RNWebGPU and View's measureLayout: the context is created at the layout size the view measures relative to itself, the ref handle survives re-renders, a state setter as the ref settles, unmount retires the context once, and a context name other than webgpu throws. Against Canvas.tsx from before fix(🎨): size the canvas context from the view's layout, not its transformed box #531 and fix(🎨): add contextId to the useImperativeHandle dependencies in Canvas #532, the first three fail.
• Canvas.spec.ts on a device: the scaled canvas's context has its layout size, not its transformed box, and its handle is the same after three re-renders.
• WebPolyfill.spec.ts: the web polyfill's native surface reports the canvas's layout size, reads it without touching the drawing buffer and delegates its DOM methods to the canvas, and a second context at the same size leaves the drawing buffer alone.

Verification

yarn lint · yarn tsc · yarn turbo run build --filter='./packages/*' · the Expo template's web build · yarn test:plugin · yarn test:unit (9 passed) · yarn check-dawn · yarn build:docs. CI's Android e2e step (debug build, Metro with CI=true) on an Android 15 emulator: 225 of 227 passed, main's 219 and the six new cases; the YUV cases of ExternalTextureColorSpace and NativeBufferWrapper fail on main on that emulator too.

On devices the whole suite passes, 227 of 227: on a Galaxy S23 (Android 14), and on an iPhone 12 Pro Max (iOS 27.0.1) built and run as CI's iOS job does on a simulator (Debug build, Metro with CI=true). main passes 221 of 221 on both. Not run here: the SwiftPM example's build and the semantic-release dry run, which needs the repository's token.