facebook/react · error

363

363

Error message

Test selector API is not supported by this renderer.

What it means

findAllNodes(hostRoot, selectors) is the entry point of React's internal test-selector API. It first checks the host-config flag supportsTestSelectors: the DOM bindings set it to true (react-dom-bindings/src/client/ReactFiberConfigDOM.js), but renderers that re-export ReactFiberConfigWithNoTestSelectors — react-native's Fabric renderer, react-art, most thin custom renderers — set it to false, and custom reconcilers get it from $$$config.supportsTestSelectors. Calling findAllNodes through a renderer that does not implement the selector host methods throws immediately.

Source

Thrown at packages/react-reconciler/src/ReactTestSelectors.js:315

    } else {
      let child = fiber.child;
      while (child !== null) {
        stack.push(child, selectorIndex);
        child = child.sibling;
      }
    }
  }

  return false;
}

export function findAllNodes(
  hostRoot: Instance,
  selectors: Array<Selector>,
): Array<Instance> {
  // $FlowFixMe[constant-condition]
  if (!supportsTestSelectors) {
    throw new Error('Test selector API is not supported by this renderer.');
  }

  const root = findFiberRootForHostRoot(hostRoot);
  const matchingFibers = findPaths(root, selectors);

  const instanceRoots: Array<Instance> = [];

  const stack = Array.from(matchingFibers);
  let index = 0;
  while (index < stack.length) {
    const node = stack[index++] as any as Fiber;
    const tag = node.tag;
    if (
      tag === HostComponent ||
      tag === HostHoistable ||
      tag === HostSingleton
    ) {
      if (isHiddenSubtree(node)) {

View on GitHub (pinned to eafeac097b)

Solutions

1. Use a renderer that implements test selectors: the DOM renderer (react-dom) is the reference implementation where supportsTestSelectors is true
2. If you own the custom reconciler, implement the host-config test-selector methods (getInstanceFromNode, getTextContent, matchAccessibilityRole, isHiddenSubtree, getBoundingRect, setFocusIfFocusable, setupIntersectionObserver) and set supportsTestSelectors: true in the Reconciler config
3. Otherwise replace findAllNodes with your environment's query API (React Native test queries, testing-library queries, renderer.toJSON traversal)

Example fix

// before (custom reconciler, selectors unsupported)
const Reconciler = require('react-reconciler');
module.exports = Reconciler({/* host config without test-selector methods */});
findAllNodes(root, [createRoleSelector('button')]); // throws

// after
const Reconciler = require('react-reconciler');
module.exports = Reconciler({
  // ...host config...
  supportsTestSelectors: true,
  getInstanceFromNode(node) { /* return Fiber or null */ },
  getTextContent(node) { /* return string */ },
  // ...other required host methods
});

// The flag is not publicly exported; detect by renderer identity
function rendererSupportsTestSelectors(renderer: string): boolean {
  return renderer === 'react-dom'; // Fabric/art/custom renderers re-export ReactFiberConfigWithNoTestSelectors
}

try {
  const nodes = findAllNodes(hostRoot, selectors);
} catch (e) {
  if (e instanceof Error && e.message === 'Test selector API is not supported by this renderer.') {
    // fall back to renderer-native queries (testing-library, RN TestRenderer)
  } else throw e;
}

When it happens

Trigger: Calling findAllNodes on a renderer built with react-reconciler whose config leaves supportsTestSelectors false or undefined; using react-native-renderer internals (ReactFiberConfigFabric re-exports the no-selectors config); third-party renderers (ink, react-three-fiber, react-pdf) that never implemented the required host methods such as getInstanceFromNode, getTextContent, matchAccessibilityRole, isHiddenSubtree, getBoundingRect, setFocusIfFocusable, setupIntersectionObserver.

Common situations: Porting a component test harness written against react-dom's internal testing build (e.g. ReactDOMTestingFB exports) to React Native or a custom renderer; upgrading a custom reconciler where the config object changed shape and supportsTestSelectors silently fell back to falsy; running FB-style selector tests against a non-DOM renderer.

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AI-assisted analysis of facebook/react@eafeac097b (2026-08-21). Data as JSON: /api/errors/0fe0eb643724d7f8. Report an issue: GitHub.