Andrew Seaford

In this article we will create a React component that returns a Promise. The promise will be the sum of two numbers. We will also create unit test to confirm the components functionality.

Component Setup

• create the app npx create-react-app demo-promise.
• Change directory cd demo-promise.
• Create a directory within src called components.
• Create a file called DemoPromise.js withing the components directory.

const DemoPromise = ({a,b}) => {
    return Promise.resolve(a+b);
}

export default DemoPromise;

• Create a file called DemoPromise.test.js withing the components directory.

import DemoPromise from "./DemoPromise"

test('Should confirm promise returns sum of a and b', async () => {
    // Arrange
    const a = 1;
    const b = 2;

    // Act
    const result = await DemoPromise({a,b});

    // Assert
    expect(result).toBe(a + b);
})

• Execute the tests npm test