var Component=(()=>{var d=Object.create;var c=Object.defineProperty;var h=Object.getOwnPropertyDescriptor;var m=Object.getOwnPropertyNames;var u=Object.getPrototypeOf,N=Object.prototype.hasOwnProperty;var k=(a,n)=>()=>(n||a((n={exports:{}}).exports,n),n.exports),g=(a,n)=>{for(var s in n)c(a,s,{get:n[s],enumerable:!0})},i=(a,n,s,l)=>{if(n&&typeof n=="object"||typeof n=="function")for(let t of m(n))!N.call(a,t)&&t!==s&&c(a,t,{get:()=>n[t],enumerable:!(l=h(n,t))||l.enumerable});return a};var y=(a,n,s)=>(s=a!=null?d(u(a)):{},i(n||!a||!a.__esModule?c(s,"default",{value:a,enumerable:!0}):s,a)),f=a=>i(c({},"__esModule",{value:!0}),a);var r=k((T,o)=>{o.exports=_jsx_runtime});var C={};g(C,{default:()=>v,frontmatter:()=>w});var e=y(r()),w={title:"Testing React Applications",publishedAt:"2024-05-28",updatedAt:"2024-09-19",summary:"Master React app testing with Jest, React Testing Library, and Cypress. Learn testing importance, types, and best practices.",tags:["React","Testing","Jest","React Testing Library","Cypress","TDD","CI/CD"],readingTime:"15",imageCaption:"Image by Clyde D'Souza on codeburst",keywords:["React testing","Jest","React Testing Library","Cypress","TDD","CI/CD","Unit testing React","Integration testing React","End-to-end testing React","Mocking in React tests"]};function p(a){let n=Object.assign({h2:"h2",p:"p",hr:"hr",ul:"ul",li:"li",strong:"strong",h3:"h3",pre:"pre",code:"code",span:"span",ol:"ol"},a.components);return(0,e.jsxs)(e.Fragment,{children:[(0,e.jsx)(n.h2,{id:"introduction",children:"Introduction"}),` `,(0,e.jsx)(n.p,{children:"\u{1F44B} Hello everyone!"}),` `,(0,e.jsx)(n.p,{children:"Let\u2019s dive into an essential aspect of developing robust React applications \u2013 testing. While it\u2019s a well-known practice in the developer community, effectively testing React apps can still be challenging."}),` `,(0,e.jsx)(n.p,{children:"In this article, we\u2019ll explore various aspects of testing React applications. We\u2019ll cover the basics, like why testing is important and the different types of tests you should write. Then we\u2019ll get our hands dirty with some practical examples using popular tools like Jest, React Testing Library, and Cypress."}),` `,(0,e.jsx)(n.p,{children:"By the end of this article, you\u2019ll have a solid understanding of how to set up a robust testing strategy for your React apps, making your development process smoother and your applications more reliable."}),` `,(0,e.jsx)(n.p,{children:"Let\u2019s get started!"}),` `,(0,e.jsx)(n.hr,{}),` `,(0,e.jsx)(n.h2,{id:"1-the-importance-of-testing",children:"1. The importance of testing"}),` `,(0,e.jsx)(n.p,{children:"Testing is a critical component of software development, and for React applications, it\u2019s no different. Here\u2019s why testing your React apps is essential:"}),` `,(0,e.jsxs)(n.ul,{children:[` `,(0,e.jsxs)(n.li,{children:[(0,e.jsx)(n.strong,{children:"Improves Code Quality"}),": Regular testing helps identify and fix bugs early in the development process, leading to higher quality code. It ensures that your code meets the specified requirements and behaves as expected under different conditions."]}),` `,(0,e.jsxs)(n.li,{children:[(0,e.jsx)(n.strong,{children:"Reduces Bugs"}),": Automated tests can catch bugs before they make it to production. By writing comprehensive tests, you can prevent many common issues that might otherwise slip through the cracks during manual testing."]}),` `,(0,e.jsxs)(n.li,{children:[(0,e.jsx)(n.strong,{children:"Enhances Maintainability"}),": As your React application grows, maintaining and updating it becomes more challenging. Tests act as a safety net, ensuring that new changes do not break existing functionality. This makes refactoring and adding new features much safer and more efficient."]}),` `,(0,e.jsxs)(n.li,{children:[(0,e.jsx)(n.strong,{children:"Increases Developer Confidence"}),": With a robust test suite, developers can make changes and add new features with greater confidence, knowing that the tests will catch any regressions or issues."]}),` `,(0,e.jsxs)(n.li,{children:[(0,e.jsx)(n.strong,{children:"Supports Continuous Integration"}),": Automated tests are essential for continuous integration and continuous deployment (CI/CD) pipelines. They ensure that every change is tested automatically, maintaining the stability and reliability of your application."]}),` `]}),` `,(0,e.jsx)(n.p,{children:"Understanding the importance of testing helps in appreciating the effort put into writing and maintaining tests. It\u2019s not just about finding bugs but also about building a reliable and maintainable codebase."}),` `,(0,e.jsx)(n.hr,{}),` `,(0,e.jsx)(n.h2,{id:"2-testing-fundamentals",children:"2. Testing fundamentals"}),` `,(0,e.jsx)(n.p,{children:"Understanding the basics of testing is crucial before diving into the specifics of testing React applications. Here are some key concepts and strategies:"}),` `,(0,e.jsx)(n.h3,{id:"types-of-testing",children:"Types of Testing"}),` `,(0,e.jsxs)(n.ul,{children:[` `,(0,e.jsxs)(n.li,{children:[(0,e.jsx)(n.strong,{children:"Unit Testing"}),": Focuses on individual components or functions. The goal is to test each part of the application in isolation to ensure it works as expected."]}),` `,(0,e.jsxs)(n.li,{children:[(0,e.jsx)(n.strong,{children:"Integration Testing"}),": Tests the interaction between different parts of the application. This ensures that different components or services work together correctly."]}),` `,(0,e.jsxs)(n.li,{children:[(0,e.jsx)(n.strong,{children:"End-to-End (E2E) Testing"}),": Simulates real user interactions with the application. These tests cover the entire application from the user interface to the back-end, ensuring everything works together as a whole."]}),` `]}),` `,(0,e.jsx)(n.h3,{id:"common-testing-tools-for-react",children:"Common Testing Tools for React"}),` `,(0,e.jsxs)(n.ul,{children:[` `,(0,e.jsxs)(n.li,{children:[(0,e.jsx)(n.strong,{children:"Jest"}),": A powerful JavaScript testing framework developed by Facebook, commonly used for unit and integration tests in React applications."]}),` `,(0,e.jsxs)(n.li,{children:[(0,e.jsx)(n.strong,{children:"React Testing Library"}),": A library for testing React components, focusing on testing user interactions rather than implementation details."]}),` `,(0,e.jsxs)(n.li,{children:[(0,e.jsx)(n.strong,{children:"Cypress"}),": A robust framework for writing end-to-end tests. It provides a developer-friendly experience and is known for its powerful features and ease of use."]}),` `]}),` `,(0,e.jsx)(n.p,{children:"Understanding these fundamentals will provide a strong foundation as we move into writing specific types of tests for React applications."}),` `,(0,e.jsx)(n.hr,{}),` `,(0,e.jsx)(n.h2,{id:"3-writing-unit-tests-with-jest-and-react-testing-library",children:"3. Writing unit tests with Jest and React Testing Library"}),` `,(0,e.jsx)(n.p,{children:"Unit testing focuses on verifying the functionality of individual components in isolation. Jest and React Testing Library are commonly used together to write unit tests for React applications."}),` `,(0,e.jsx)(n.h3,{id:"setting-up-your-testing-environment",children:"Setting Up Your Testing Environment"}),` `,(0,e.jsx)(n.p,{children:"First, you need to install Jest and React Testing Library. If you haven\u2019t already, you can add them to your project using npm or yarn:"}),` `,(0,e.jsx)(n.pre,{className:"language-bash",children:(0,e.jsxs)(n.code,{className:"language-bash code-highlight",children:[(0,e.jsxs)(n.span,{className:"code-line",children:[(0,e.jsx)(n.span,{className:"token function",children:"npm"})," ",(0,e.jsx)(n.span,{className:"token function",children:"install"}),` --save-dev jest @testing-library/react @testing-library/jest-dom `]}),(0,e.jsxs)(n.span,{className:"code-line",children:[(0,e.jsx)(n.span,{className:"token comment",children:"# or"}),` `]}),(0,e.jsxs)(n.span,{className:"code-line",children:[(0,e.jsx)(n.span,{className:"token function",children:"yarn"})," ",(0,e.jsx)(n.span,{className:"token function",children:"add"})," ",(0,e.jsx)(n.span,{className:"token parameter variable",children:"--dev"}),` jest @testing-library/react @testing-library/jest-dom `]})]})}),` `,(0,e.jsx)(n.p,{children:"Next, create a setupTests.js file in your src directory to configure Jest and React Testing Library:"}),` `,(0,e.jsx)(n.pre,{className:"language-javascript",children:(0,e.jsxs)(n.code,{className:"language-javascript code-highlight",children:[(0,e.jsxs)(n.span,{className:"code-line",children:[(0,e.jsx)(n.span,{className:"token comment",children:"// src/setupTests.js"}),` `]}),(0,e.jsxs)(n.span,{className:"code-line",children:[(0,e.jsx)(n.span,{className:"token keyword module",children:"import"})," ",(0,e.jsx)(n.span,{className:"token string",children:"'@testing-library/jest-dom'"}),(0,e.jsx)(n.span,{className:"token punctuation",children:";"}),` `]})]})}),` `,(0,e.jsx)(n.p,{children:"Ensure your package.json includes the following configuration for Jest:"}),` `,(0,e.jsx)(n.pre,{className:"language-json",children:(0,e.jsxs)(n.code,{className:"language-json code-highlight",children:[(0,e.jsxs)(n.span,{className:"code-line",children:[(0,e.jsx)(n.span,{className:"token punctuation",children:"{"}),` `]}),(0,e.jsxs)(n.span,{className:"code-line",children:[" ",(0,e.jsx)(n.span,{className:"token property",children:'"scripts"'}),(0,e.jsx)(n.span,{className:"token operator",children:":"})," ",(0,e.jsx)(n.span,{className:"token punctuation",children:"{"}),` `]}),(0,e.jsxs)(n.span,{className:"code-line",children:[" ",(0,e.jsx)(n.span,{className:"token property",children:'"test"'}),(0,e.jsx)(n.span,{className:"token operator",children:":"})," ",(0,e.jsx)(n.span,{className:"token string",children:'"jest"'}),` `]}),(0,e.jsxs)(n.span,{className:"code-line",children:[" ",(0,e.jsx)(n.span,{className:"token punctuation",children:"}"}),(0,e.jsx)(n.span,{className:"token punctuation",children:","}),` `]}),(0,e.jsxs)(n.span,{className:"code-line",children:[" ",(0,e.jsx)(n.span,{className:"token property",children:'"jest"'}),(0,e.jsx)(n.span,{className:"token operator",children:":"})," ",(0,e.jsx)(n.span,{className:"token punctuation",children:"{"}),` `]}),(0,e.jsxs)(n.span,{className:"code-line",children:[" ",(0,e.jsx)(n.span,{className:"token property",children:'"setupFilesAfterEnv"'}),(0,e.jsx)(n.span,{className:"token operator",children:":"})," ",(0,e.jsx)(n.span,{className:"token punctuation",children:"["}),(0,e.jsx)(n.span,{className:"token string",children:'"/src/setupTests.js"'}),(0,e.jsx)(n.span,{className:"token punctuation",children:"]"}),(0,e.jsx)(n.span,{className:"token punctuation",children:","}),` `]}),(0,e.jsxs)(n.span,{className:"code-line",children:[" ",(0,e.jsx)(n.span,{className:"token property",children:'"testEnvironment"'}),(0,e.jsx)(n.span,{className:"token operator",children:":"})," ",(0,e.jsx)(n.span,{className:"token string",children:'"jsdom"'}),` `]}),(0,e.jsxs)(n.span,{className:"code-line",children:[" ",(0,e.jsx)(n.span,{className:"token punctuation",children:"}"}),` `]}),(0,e.jsxs)(n.span,{className:"code-line",children:[(0,e.jsx)(n.span,{className:"token punctuation",children:"}"}),` `]})]})}),` `,(0,e.jsx)(n.h3,{id:"writing-your-first-unit-test",children:"Writing your first unit test"}),` `,(0,e.jsx)(n.p,{children:"Let\u2019s start with a simple example. 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as needed.`,` `,(0,e.jsx)(n.pre,{className:"language-json",children:(0,e.jsxs)(n.code,{className:"language-json code-highlight",children:[(0,e.jsxs)(n.span,{className:"code-line",children:[(0,e.jsx)(n.span,{className:"token punctuation",children:"{"}),` `]}),(0,e.jsxs)(n.span,{className:"code-line",children:[" ",(0,e.jsx)(n.span,{className:"token property",children:'"baseUrl"'}),(0,e.jsx)(n.span,{className:"token operator",children:":"})," ",(0,e.jsx)(n.span,{className:"token string",children:'"http://localhost:3000"'}),` `]}),(0,e.jsxs)(n.span,{className:"code-line",children:[(0,e.jsx)(n.span,{className:"token punctuation",children:"}"}),` `]})]})}),` `]}),` `]}),` `,(0,e.jsx)(n.h3,{id:"writing-e2e-tests",children:"Writing E2E Tests"}),` `,(0,e.jsx)(n.p,{children:"Let\u2019s write a simple E2E test to verify the login functionality of a React application:"}),` `,(0,e.jsxs)(n.ol,{children:[` `,(0,e.jsxs)(n.li,{children:[` `,(0,e.jsxs)(n.p,{children:[(0,e.jsx)(n.strong,{children:"Create 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This step confirms that the test is detecting the absence of the desired functionality."]}),` `,(0,e.jsxs)(n.li,{children:[(0,e.jsx)(n.strong,{children:"Write the Code"}),": Write the minimal amount of code necessary to make the test pass."]}),` `,(0,e.jsxs)(n.li,{children:[(0,e.jsx)(n.strong,{children:"Run the Test Again"}),": Run the test again to ensure it passes with the new code."]}),` `,(0,e.jsxs)(n.li,{children:[(0,e.jsx)(n.strong,{children:"Refactor"}),": Refactor the code to improve its structure and readability while ensuring the tests still pass."]}),` `]}),` `,(0,e.jsx)(n.h3,{id:"tdd-workflow",children:"TDD Workflow"}),` `,(0,e.jsxs)(n.ol,{children:[` `,(0,e.jsxs)(n.li,{children:[(0,e.jsx)(n.strong,{children:"Red Phase"}),": Write a failing test that defines a function or feature."]}),` `,(0,e.jsxs)(n.li,{children:[(0,e.jsx)(n.strong,{children:"Green Phase"}),": Write the code to pass the test."]}),` `,(0,e.jsxs)(n.li,{children:[(0,e.jsx)(n.strong,{children:"Refactor Phase"}),": Refactor the code for optimization and clarity, ensuring the test still passes."]}),` `]}),` `,(0,e.jsx)(n.h3,{id:"advantages-of-tdd",children:"Advantages of TDD"}),` `,(0,e.jsxs)(n.ul,{children:[` `,(0,e.jsxs)(n.li,{children:[(0,e.jsx)(n.strong,{children:"Improved Code Quality"}),": Writing tests first ensures that each piece of functionality is clearly defined and tested."]}),` `,(0,e.jsxs)(n.li,{children:[(0,e.jsx)(n.strong,{children:"Early Bug Detection"}),": Bugs are caught early in the development process, reducing the cost and effort of fixing them later."]}),` `,(0,e.jsxs)(n.li,{children:[(0,e.jsx)(n.strong,{children:"Better Design"}),": TDD encourages modular and maintainable code design."]}),` `,(0,e.jsxs)(n.li,{children:[(0,e.jsx)(n.strong,{children:"Confidence in Code Changes"}),": Tests provide a safety net that gives developers confidence when making changes or adding new features."]}),` `]}),` `,(0,e.jsx)(n.h3,{id:"practical-example",children:"Practical Example"}),` `,(0,e.jsx)(n.p,{children:"Let\u2019s walk through a simple TDD example for a React component:"}),` `,(0,e.jsx)(n.p,{children:(0,e.jsx)(n.strong,{children:"Step 1: Write a Test"})}),` `,(0,e.jsx)(n.p,{children:"Suppose we want to create a Counter component. 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Best practices and Tips"}),` `,(0,e.jsx)(n.p,{children:"Writing effective tests for your React applications involves following best practices that ensure your tests are maintainable, reliable, and efficient. Here are some tips to help you achieve that:"}),` `,(0,e.jsx)(n.h3,{id:"effective-test-writing",children:"Effective Test Writing"}),` `,(0,e.jsxs)(n.ul,{children:[` `,(0,e.jsxs)(n.li,{children:[(0,e.jsx)(n.strong,{children:"Write Tests Early"}),": Incorporate testing into your development process from the beginning. Writing tests early helps catch issues sooner and ensures new features are covered by tests."]}),` `,(0,e.jsxs)(n.li,{children:[(0,e.jsx)(n.strong,{children:"Test Behavior, Not Implementation"}),": Focus on testing the behavior and output of your components rather than their implementation details. This makes your tests more robust and less likely to break with refactoring."]}),` `,(0,e.jsxs)(n.li,{children:[(0,e.jsx)(n.strong,{children:"Keep Tests Small and Focused"}),": Write small, focused tests that cover specific pieces of functionality. This makes it easier to understand and maintain your test suite."]}),` `]}),` `,(0,e.jsx)(n.h3,{id:"optimizing-test-performance",children:"Optimizing Test Performance"}),` `,(0,e.jsxs)(n.ul,{children:[` `,(0,e.jsxs)(n.li,{children:[(0,e.jsx)(n.strong,{children:"Avoid Unnecessary Re-renders"}),": Use utility functions like rerender from React Testing Library to avoid unnecessary re-renders in your tests."]}),` `,(0,e.jsxs)(n.li,{children:[(0,e.jsx)(n.strong,{children:"Mock Expensive Operations"}),": Mock operations that are resource-intensive or slow, such as network requests, to speed up your tests."]}),` `,(0,e.jsxs)(n.li,{children:[(0,e.jsx)(n.strong,{children:"Run Tests in Parallel"}),": Configure your testing framework to run tests in parallel where possible, reducing overall test execution time."]}),` `]}),` `,(0,e.jsx)(n.h3,{id:"managing-test-data",children:"Managing Test Data"}),` `,(0,e.jsxs)(n.ul,{children:[` `,(0,e.jsxs)(n.li,{children:[(0,e.jsx)(n.strong,{children:"Use Factories for Test Data"}),": Create factories or fixtures for generating test data. This ensures consistency and makes it easier to set up tests."]}),` `,(0,e.jsxs)(n.li,{children:[(0,e.jsx)(n.strong,{children:"Clean Up After Tests"}),": Ensure that any side effects created during tests are cleaned up. Use Jest\u2019s afterEach or afterAll hooks to reset state or clear mocks."]}),` `]}),` `,(0,e.jsx)(n.h3,{id:"common-challenges-and-solutions",children:"Common Challenges and Solutions"}),` `,(0,e.jsxs)(n.ul,{children:[` `,(0,e.jsxs)(n.li,{children:[(0,e.jsx)(n.strong,{children:"Flaky Tests"}),": Identify and fix flaky tests that sometimes pass and sometimes fail. This can be due to timing issues, reliance on external services, or random data."]}),` `,(0,e.jsxs)(n.li,{children:[(0,e.jsx)(n.strong,{children:"Testing Asynchronous Code"}),": Use utilities like waitFor or findBy from React Testing Library to handle asynchronous operations in your tests. Ensure that your tests account for delays or async behavior."]}),` `,(0,e.jsxs)(n.li,{children:[(0,e.jsx)(n.strong,{children:"Handling Dependencies"}),": Use mocking to handle dependencies that are difficult to control in tests, such as API calls or global objects."]}),` `]}),` `,(0,e.jsx)(n.hr,{}),` `,(0,e.jsx)(n.h2,{id:"9-continuous-integration-and-deployment-cicd",children:"9. Continuous Integration and Deployment (CI/CD)"}),` `,(0,e.jsx)(n.p,{children:"Continuous Integration and Continuous Deployment (CI/CD) are essential practices for modern software development. They automate the process of integrating code changes, running tests, and deploying applications, ensuring that your software is always in a deployable state."}),` `,(0,e.jsx)(n.h3,{id:"role-of-cicd-in-testing",children:"Role of CI/CD in Testing"}),` `,(0,e.jsx)(n.p,{children:"CI/CD pipelines automate the testing process, allowing you to:"}),` `,(0,e.jsxs)(n.ul,{children:[` `,(0,e.jsxs)(n.li,{children:[(0,e.jsx)(n.strong,{children:"Run Tests Automatically"}),": Ensure that tests are run automatically on every code change, catching bugs early in the development process."]}),` `,(0,e.jsxs)(n.li,{children:[(0,e.jsx)(n.strong,{children:"Maintain Code Quality"}),": Enforce code quality standards by running linting and formatting checks as part of the pipeline."]}),` `,(0,e.jsxs)(n.li,{children:[(0,e.jsx)(n.strong,{children:"Deploy Continuously"}),": Deploy code changes to production or staging environments automatically, ensuring that new features and fixes are available to users as soon as they are ready."]}),` `]}),` `,(0,e.jsx)(n.h3,{id:"popular-cicd-platforms",children:"Popular CI/CD Platforms"}),` `,(0,e.jsx)(n.p,{children:"Several CI/CD platforms are popular in the development community for their ease of use and powerful features. Here are a few:"}),` `,(0,e.jsxs)(n.ul,{children:[` `,(0,e.jsxs)(n.li,{children:[(0,e.jsx)(n.strong,{children:"GitHub Actions"}),": Integrated with GitHub repositories, it allows you to automate workflows directly within your GitHub environment."]}),` `,(0,e.jsxs)(n.li,{children:[(0,e.jsx)(n.strong,{children:"CircleCI"}),": Known for its speed and efficiency, it supports various configurations and is easy to integrate with multiple environments."]}),` `,(0,e.jsxs)(n.li,{children:[(0,e.jsx)(n.strong,{children:"Travis CI"}),": Popular for its simplicity and ease of setup, especially for open-source projects."]}),` `]}),` `,(0,e.jsx)(n.h3,{id:"running-and-monitoring-cicd-pipelines",children:"Running and Monitoring CI/CD Pipelines"}),` `,(0,e.jsx)(n.p,{children:"Once your CI/CD pipeline is set up, every code change will trigger the workflow, running your tests and providing feedback. You can monitor the status of your workflows directly in the GitHub Actions tab of your repository."}),` `,(0,e.jsx)(n.h3,{id:"benefits",children:"Benefits:"}),` `,(0,e.jsxs)(n.ul,{children:[` `,(0,e.jsxs)(n.li,{children:[(0,e.jsx)(n.strong,{children:"Consistency"}),": Ensure that tests are run consistently and automatically on every code change."]}),` `,(0,e.jsxs)(n.li,{children:[(0,e.jsx)(n.strong,{children:"Early Bug Detection"}),": Catch bugs early in the development process before they make it to production."]}),` `,(0,e.jsxs)(n.li,{children:[(0,e.jsx)(n.strong,{children:"Continuous Delivery"}),": Automate the deployment process, ensuring that your application is always in a deployable state."]}),` `]}),` `,(0,e.jsx)(n.p,{children:"By integrating CI/CD into your development workflow, you can maintain high code quality, reduce the risk of introducing bugs, and ensure that new features are delivered to users quickly and reliably."}),` `,(0,e.jsx)(n.h2,{id:"conclusion",children:"Conclusion"}),` `,(0,e.jsx)(n.p,{children:"Implementing a robust testing strategy is crucial for delivering high-quality, reliable software. By integrating tools like Jest, React Testing Library, and Cypress into your workflow, you can catch bugs early, improve code quality, and ensure a smooth user experience. Continuous Integration and Deployment (CI/CD) further enhance this process by automating tests and deployments, maintaining the stability of your application."}),` `,(0,e.jsx)(n.p,{children:"Remember, testing is not just about finding bugs\u2014it\u2019s about ensuring that your code behaves as expected and continues to do so as it evolves. By prioritizing testing in your development workflow, you can build more reliable and maintainable React applications."})]})}function b(a={}){let{wrapper:n}=a.components||{};return n?(0,e.jsx)(n,Object.assign({},a,{children:(0,e.jsx)(p,a)})):p(a)}var v=b;return f(C);})(); ;return Component;

Mario Yonan

Oct 29, 2024

Aug 10, 2024

May 28, 2024