react-native-web-internals/dist/esm/modules/useStable/__tests__/index-test.mjs

React Native for Web

import * as ReactDOM from "react-dom";
import { act } from "react-dom/test-utils";
import useStable from "..";
import { jsx } from "react/jsx-runtime";
function createRoot(rootNode) {
  return {
    render(element) {
      ReactDOM.render(element, rootNode);
    }
  };
}
describe("useStable", () => {
  let root,
    rootNode,
    spy = {};
  const TestComponent = ({
    initialValueCallback
  }) => {
    const value = useStable(initialValueCallback);
    return spy.value = value, null;
  };
  beforeEach(() => {
    spy = {}, rootNode = document.createElement("div"), document.body.appendChild(rootNode), root = createRoot(rootNode);
  }), afterEach(() => {
    root.render(null), document.body.removeChild(rootNode), rootNode = null, root = null;
  }), test("correctly sets the initial value", () => {
    const initialValueCallback = () => 5;
    act(() => {
      root.render(/* @__PURE__ */jsx(TestComponent, {
        initialValueCallback
      }));
    }), expect(spy.value).toBe(5);
  }), test("does not change the value", () => {
    let counter = 0;
    const initialValueCallback = () => counter++;
    act(() => {
      root.render(/* @__PURE__ */jsx(TestComponent, {
        initialValueCallback
      }));
    }), expect(spy.value).toBe(0), act(() => {
      root.render(/* @__PURE__ */jsx(TestComponent, {
        initialValueCallback
      }));
    }), expect(spy.value).toBe(0);
  }), test("only calls the callback once", () => {
    let counter = 0;
    const initialValueCallback = () => counter++;
    act(() => {
      root.render(/* @__PURE__ */jsx(TestComponent, {
        initialValueCallback
      }));
    }), expect(counter).toBe(1), act(() => {
      root.render(/* @__PURE__ */jsx(TestComponent, {
        initialValueCallback
      }));
    }), expect(counter).toBe(1);
  }), test("does not change the value if the callback initially returns null", () => {
    let counter = 0;
    const initialValueCallback = () => counter === 0 ? (counter++, null) : counter++;
    act(() => {
      root.render(/* @__PURE__ */jsx(TestComponent, {
        initialValueCallback
      }));
    }), expect(spy.value).toBe(null), act(() => {
      root.render(/* @__PURE__ */jsx(TestComponent, {
        initialValueCallback
      }));
    }), expect(spy.value).toBe(null);
  });
});
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