今天來學習 Jest 測試的 Group 寫法：

情境：如果我的測試檔案中，有多個測試函式。我想要把相關連的測試群組起來，方便執行測試時一起執行。

原本的寫法：

// Button
test("Render a Log In Button", () => {
    render(<LogInButton />);
    
    const textEl = screen.getByText("Log In");
    expect(textEl).toBeInTheDocument();
});

// Button
test("Render a Log Out Button", () => {
    render(<LogInButton />);
    
    const textEl = screen.getByText("Log Out");
    expect(textEl).toBeInTheDocument();
});

// Greet
test("Render a Greet Component", () => {
    render(<Greet name="Joanna" />);
    
    const textEl = screen.getByText("Hello");
    expect(textEl).toBeInTheDocument();
});

分組寫法：加入關鍵字 describe

// Button
describe("Button", () => {
    test("Render a Log In Button", () => {
        render(<LogInButton />);

        const textEl = screen.getByText("Log In");
        expect(textEl).toBeInTheDocument();
    });

    test("Render a Log Out Button", () => {
        render(<LogInButton />);

        const textEl = screen.getByText("Log Out");
        expect(textEl).toBeInTheDocument();
    });
});


// Greet
test("Render a Greet Component", () => {
    render(<Greet name="Joanna" />);
    
    const textEl = screen.getByText("Hello");
    expect(textEl).toBeInTheDocument();
});

補充：

describe() 也有提供 describe.only() describe.skip() 的寫法，方便群組測試執行。