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Testing Array Spread Component Implementation in Create React App

This test suite validates the array spread operator functionality in a React component within Create React App. It ensures proper rendering and execution of array spread operations in React components while maintaining compatibility with modern JavaScript features.

Test Coverage Overview

The test coverage focuses on the fundamental rendering capabilities of a React component utilizing array spread operations.

Tests basic component mounting
Verifies asynchronous rendering completion
Ensures DOM integration
Validates component lifecycle with promises

Implementation Analysis

The testing approach employs Jest’s asynchronous testing capabilities combined with React’s rendering lifecycle.

The implementation uses Promise-based assertions to verify component mounting, leveraging ReactDOM.render with a callback pattern for completion verification. The test utilizes modern JavaScript features including arrow functions and promise-based async operations.

Technical Details

Testing Framework: Jest
React Testing Dependencies: ReactDOM
Component: ArraySpread
Setup: Dynamic div creation
Async Pattern: Promise-based rendering verification
DOM Manipulation: document.createElement

Best Practices Demonstrated

The test exemplifies clean testing practices by isolating component rendering and utilizing asynchronous patterns effectively.

Proper cleanup of DOM elements
Async testing patterns
Component isolation
Event-driven completion verification
Modern JavaScript feature usage

facebook/create-react-app

packages/react-scripts/fixtures/kitchensink/template/src/features/syntax/ArraySpread.test.js

            
/**
 * Copyright (c) 2015-present, Facebook, Inc.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */

import React from 'react';
import ReactDOM from 'react-dom';
import ArraySpread from './ArraySpread';

describe('array spread', () => {
  it('renders without crashing', () => {
    const div = document.createElement('div');
    return new Promise(resolve => {
      ReactDOM.render(<ArraySpread onReady={resolve} />, div);
    });
  });
});