React 基础知识~单元测试/自定义钩子

import "./app.css";
import counter from "./component/counter/counter";

function app() {
  return (
    <div classname="app">
      <counter />
    </div>
  );
}

export default app;

import react, { usestate } from "react";
import { usecounter } from "../../hooks/usecounter";

const counter = () => {
const { count, increment } = usecounter({ initialcount: 10 });

  return (
    <div>
      <h1>{count}</h1>
      <button onclick={() => increment()}>increment</button>
    </div>
  );
};

export default counter;

import react, { usestate } from "react";
import { usecounterprops } from "./usecounter.type";

type usecounterprops = {
  initialcount?: number;
};


export const usecounter = ({ initialcount = 0 }: usecounterprops = {}) => {
  const [count, setcount] = usestate(initialcount);
  const increment = () => setcount((prev) => prev + 1);

  return { count, increment };
};

import { renderHook } from "@testing-library/react";
import { useCounter } from "./useCounter";
import { act } from "react-dom/test-utils";

describe("useCounter", () => {
  test("Should render the initial count", () => {
    const { result } = renderHook(useCounter, {
      initialProps: { initialCount: 10 },
    });
    expect(result.current.count).toBe(10);
  });

  test("Increment the  count", () => {
    const { result } = renderHook(useCounter);
    act(() => {
      result.current.increment();
    });
    expect(result.current.count).toBe(1);
  });
});