How to Build AI-Powered Testing Tools with Codeium 1.5 and Jest 30 for React 19

Testing React applications is critical for maintaining code quality, but writing comprehensive test suites manually is time-consuming. By combining Jest 30’s robust testing capabilities with Codeium 1.5’s AI-driven code generation, you can build custom AI-powered testing tools that automate test creation, detect edge cases, and reduce manual effort. This guide walks through the end-to-end process for React 19 projects.

Prerequisites

• Node.js 20+ installed locally
• Basic knowledge of React 19 and Jest
• Codeium 1.5 account (free tier available)
• React 19 project (we’ll create one from scratch if you don’t have one)

Step 1: Set Up a React 19 Project

First, create a new React 19 project using Vite (the recommended build tool for React 19):

npm create vite@latest react-19-test-demo -- --template react
cd react-19-test-demo
npm install

Verify React 19 is installed by checking package.json:

{
  "dependencies": {
    "react": "^19.0.0",
    "react-dom": "^19.0.0"
  }
}

Step 2: Install and Configure Jest 30 for React 19

Jest 30 includes native support for React 19’s concurrent features and the React Compiler. Install Jest 30 and required dependencies:

npm install --save-dev jest@30 @testing-library/react@16 @testing-library/jest-dom@6

Create a jest.config.js file in the project root:

module.exports = {
  testEnvironment: 'jsdom',
  transform: {
    '^.+\\.[tj]sx?$': 'babel-jest',
  },
  moduleNameMapper: {
    '\\.(css|less|scss|sass)$': 'identity-obj-proxy',
  },
  setupFilesAfterSetup: ['<rootDir>/jest.setup.js'],
};

Create jest.setup.js to import Jest DOM matchers:

import '@testing-library/jest-dom';

Step 3: Set Up Codeium 1.5 for AI Test Generation

Codeium 1.5 adds specialized support for test generation, including context-aware Jest test creation for React components. Install the Codeium CLI:

npm install -g @codeium/cli@1.5

Authenticate with your Codeium account:

codeium auth login

Enable test generation in your project by creating a codeium.config.json file:

{
  "features": {
    "testGeneration": true,
    "testFramework": "jest",
    "componentLibrary": "react"
  },
  "reactVersion": 19
}

Step 4: Build Custom AI-Powered Testing Tools

We’ll build a custom CLI tool that uses Codeium 1.5’s API to generate Jest tests for React components automatically. First, install required dependencies:

npm install --save-dev axios dotenv

Create a .env file with your Codeium API key (retrieve from Codeium dashboard):

CODEIUM_API_KEY=your_api_key_here

Create a generate-tests.js script:

require('dotenv').config();
const axios = require('axios');
const fs = require('fs');
const path = require('path');

const generateTests = async (componentPath) => {
  const componentCode = fs.readFileSync(componentPath, 'utf8');
  const componentName = path.basename(componentPath, path.extname(componentPath));

  const response = await axios.post(
    'https://api.codeium.com/v1/generate-tests',
    {
      code: componentCode,
      framework: 'jest',
      library: 'react',
      version: 19,
      includeEdgeCases: true,
    },
    {
      headers: {
        'Authorization': `Bearer ${process.env.CODEIUM_API_KEY}`,
        'Content-Type': 'application/json',
      },
    }
  );

  const testCode = response.data.testCode;
  const testPath = path.join(path.dirname(componentPath), `${componentName}.test.js`);
  fs.writeFileSync(testPath, testCode);
  console.log(`Generated test file: ${testPath}`);
};

// Run for a sample component
generateTests(path.join(__dirname, 'src', 'components', 'Counter.jsx'));

Create a sample Counter.jsx component to test:

import { useState } from 'react';

export default function Counter() {
  const [count, setCount] = useState(0);

  return (
    <div>
      <h2 data-testid="count">Count: {count}</h2>
      <button data-testid="increment" onClick={() => setCount(count + 1)}>
        Increment
      </button>
      <button data-testid="decrement" onClick={() => setCount(count - 1)}>
        Decrement
      </button>
    </div>
  );
}

Run the test generation script:

node generate-tests.js

Codeium 1.5 will generate a Jest test file for the Counter component, including tests for initial state, increment/decrement functionality, and edge cases like negative counts.

Step 5: Integrate with CI/CD

Add the AI-powered test generation to your CI pipeline (e.g., GitHub Actions) to automatically generate and run tests on every pull request:

name: Test React 19 App
on: [pull_request]

jobs:
  test:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-node@v4
        with:
          node-version: 20
      - run: npm install
      - run: node generate-tests.js
      - run: npx jest@30

Best Practices

• Review all AI-generated tests before committing to avoid false positives.
• Use Codeium’s context window to include related components for more accurate test generation.
• Combine AI-generated tests with manually written tests for critical business logic.
• Update Codeium config when upgrading React or Jest versions.

Conclusion

By combining Jest 30’s testing capabilities with Codeium 1.5’s AI, you can build powerful custom testing tools that save time and improve test coverage for React 19 applications. Start with the sample tool above and extend it to fit your team’s workflow.