React 基础知识~单元测试/描述测试

• 当我测试一些当前代码时，我可以使用describe函数将代码分组。

• 在本例中，我创建了一个计数器应用程序。

・src/example.jsx

import counter from "./components/counter";

const example = () => {
  const origincount = 0;

  return ;
};

export default example;

・src/components/counter.jsx

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import { usestate } from "react";

const counter = (props) => {
  const { origincount } = props;
  const [count, setcount] = usestate(origincount);

  const countup = () => {
    setcount(count + 1);
  };

  const countdown = () => {
    setcount(count - 1);
  };

  const countclear = () => {
    setcount(0);
  };

  return (
    

      
counter test
      

        current count:{count}
      
      

        countup
        countdown
        clear
      
    
  );
};

export default counter;

・src/components/counter.test.jsx

import { fireEvent, render, screen } from "@testing-library/react";
import Counter from "./Counter";

//A group for initial test
describe("Counter", () => {
 describe("Check the initial display", () => {

　　// ①　A Confirming the Initial State
    test("Whether 
    test("Whether the current count is 0 or not", () => {
      render();

      const spanElBeforeUpdate = screen.getByText("Current count:0");
      expect(spanElBeforeUpdate).toBeInTheDocument();
    });
  });

  //A group for actions tests
  describe("Control buttons", () => {

    // ①　count up
    test("Whether the current count changes into 1 or not, in case the 
      countup button is clicked", () => {
      render();

      const spanElBeforeUpdate = screen.getByText("Current count:0");
      expect(spanElBeforeUpdate).toBeInTheDocument();

      const btn = screen.getByRole("button", { name: "Countup" });
      fireEvent.click(btn);

      const spanEl = screen.getByText("Current count:1");
      expect(spanEl).toBeInTheDocument();
    });
　　
　　// ②　count down 
    test("Whether the current count  changes into -1 or not, in case the 
      countdown button is clicked ", () => {
      render();

      const spanElBeforeUpdate = screen.getByText("Current count:0");
      expect(spanElBeforeUpdate).toBeInTheDocument();

      const btn = screen.getByRole("button", { name: "Countdown" });
      fireEvent.click(btn);

      const spanEl = screen.getByText("Current count:-1");
      expect(spanEl).toBeInTheDocument();
    });

　　// ③　count clear 
    test("Whether the current count changes into 0 or not, in case the 
      clear button is clicked ", () => {
      render();

      const spanElBeforeUpdate = screen.getByText("Current count:0");
      expect(spanElBeforeUpdate).toBeInTheDocument();

      const btn = screen.getByRole("button", { name: "Clear" });
      fireEvent.click(btn);

      const spanEl = screen.getByText("Current count:0");
      expect(spanEl).toBeInTheDocument();
    });
  });
});

・计数

・倒计时
・倒计时
・成功
・失败