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Testing Computed Properties Component Rendering in Create React App

This test suite validates the implementation of computed properties in React components within Create React App. It focuses on ensuring components using computed properties can render successfully without crashing and properly handle asynchronous operations.

Test Coverage Overview

The test coverage focuses on the fundamental rendering capability of components utilizing computed properties in React.

Tests basic component mounting
Verifies async rendering behavior
Validates component lifecycle with computed properties
Ensures DOM integration

Implementation Analysis

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

The implementation uses Promise-based assertions to handle component mounting, specifically utilizing ReactDOM.render with a callback pattern to ensure proper component initialization.

Promise-based test structure
Component mounting verification
Async rendering validation

Technical Details

Testing Framework: Jest
React Testing Utilities: ReactDOM
Test Environment: jsdom
Component Type: Functional React Component
Async Pattern: Promise resolution

Best Practices Demonstrated

The test suite exemplifies several React testing best practices, focusing on isolation and async handling.

Clean test setup with isolated DOM elements
Proper async test handling
Component cleanup consideration
Single responsibility principle in test cases

facebook/create-react-app

packages/react-scripts/fixtures/kitchensink/template/src/features/syntax/ComputedProperties.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 ComputedProperties from './ComputedProperties';

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