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Vadym M, Jest Developer

Last Job: 25 Sep 2024
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Programming Skills Verified
CV Verified

- 5+ years of experience as a Front-end JavaScript Developer. - 5+ years of experience in React.js; - Deep experience in Next.js technology; - Experience with WebRTC, Soket.io; - Good knowledge of Tailwind CSS, Bootstrap, and Chakra UI; - Experience working with Redux, and Docker; - Familiar with Node.js; - Strong abilities working with Web3; - Proficiency in testing frameworks like Jest and Cypress; - E-commerce, web, and mobile applications, including learning platforms, chatbots, dApps, and cryptocurrency wallet extensions.

Jest

Jest

JavaScript

JavaScript   5 yr.

Web3.js

Web3.js

React

React

WebRTC (Web Real-Time Communication)

WebRTC (Web Real-Time Communication)

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Vlad L., Jest Developer

$35/hr
Last Job: 6 Sep 2024
Identity Verified
Language Verified
Programming Skills Verified
CV Verified

- 9 years of proven professional expertise in the IT industry; - Advanced experience in Web Development using JavaScript 7+ years; - Solid experience in software development using ReactJS and React Native (6+ years); 3 Years with Node.js - Good experience in Web development using PHP; - Beginner experience in Web Development using Ruby on Rails; - Beginner experience in Web Development using Java; - Upper-Intermediate English

Jest

Jest

React

React   6 yr.

React Native

React Native   2 yr.

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Ruslan, Jest Developer

Last Job: 19 Dec 2023

A full stack software engineer with 4+ years of experience specializing in web development for domains such as e-commerce, adTech, and media. Expertise in JavaScript, TypeScript, and PHP with hands-on experience in key backend technologies including Node.js, Nest JS, Express.js, and Laravel, as well as front-end development with React.js and associated technologies. Proven track record in implementing complex database schemas, facilitating efficient communication with RabbitMQ, and ensuring platform security with OAuth2. Solid foundation in cloud services (AWS, GCP), DevOps (Docker), and automated testing (Jest), reflecting a versatile and adaptive technical skillset.

Jest

Jest

JavaScript

JavaScript

Node.js

Node.js

NestJS

NestJS

React

React

Redux

Redux

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Egor G., Jest Developer

Last Job: 4 Jul 2023

- 4 years of professional experience with front-end and back-end development - Back-end: NodeJS (Express, Nest), REST API, Docker, Google, Facebook auth, Postgres - Front-end: HTML, CSS, BEM, SASS/SCSS, LESS, Bootstrap, Material-UI, ReactJS, Redux, Redux-Thunk, React-query, Webpack, Vite, Jest, Lodash - Available in 1 week after approval for the project

Jest

Jest

Node.js

Node.js

React

React

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Danil T., Jest Developer

Last Job: 4 Jul 2023

- 4+ years of professional experience using front-end and back-end technologies - Back-end: NodeJS, Express, Nest, REST API, Docker, Google, Facebook auth, Postgres - Front-end: React, Redux, Redux-Thunk, React-query, Webpack, Material-UI, Vite, Jest, Lodash, HTML, CSS, BEM, SASS/SCSS, LESS, Bootstrap - Intermediate English - Available in 2 weeks after approval for the project

Jest

Jest

Node.js

Node.js

React

React

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Roman Masniuk August 25, 2023
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A Jest Developer is a specialist in the Jest framework/language, focusing on developing applications or systems that require expertise in this particular technology.

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If your project involves developing applications or systems that rely heavily on Jest, then hiring a Jest Developer would be essential.

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The cost depends on factors like experience and project scope, but Upstaff.com offers competitive rates and flexible pricing options.

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All developers undergo a strict vetting process to ensure they meet our high standards of expertise and professionalism.

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Table of Contents

How and where is Jest used?

How and where
Case NameCase Description
Unit TestingJest is widely used for unit testing JavaScript applications. It provides a simple and intuitive API for writing test cases and assertions. With features like snapshot testing, mocking, and code coverage reporting, Jest helps developers ensure the correctness of their code at the unit level.
React Component TestingJest is the default testing framework for React applications created with Create React App. It offers specific utilities for testing React components, such as the ability to render components and simulate user interactions. With Jest, developers can verify the behavior and rendering of React components in isolation.
Integration TestingJest can be used for integration testing, where multiple components or modules are tested together to ensure their proper interaction. By leveraging Jest’s testing capabilities and tools like mocks and spies, developers can verify the integration between different parts of their application and identify potential issues.
Asynchronous TestingJest provides built-in support for handling asynchronous operations in tests. It offers various methods to handle promises, timers, and asynchronous code, making it easier to write and maintain tests that involve asynchronous behavior. This allows developers to thoroughly test asynchronous operations in their applications.
Code Coverage AnalysisJest includes a built-in code coverage tool that helps developers measure the extent to which their tests cover their codebase. It generates detailed reports highlighting the lines of code that were executed during testing and identifies areas that lack test coverage. This enables developers to identify and improve the overall quality and reliability of their code.
Snapshot TestingJest’s snapshot testing feature allows developers to capture a representation of the rendered output of a component or module and compare it against a previously saved “snapshot.” This helps detect unexpected changes in the UI or output of a component, ensuring that any unintended modifications are identified and addressed.
Mocking DependenciesJest offers powerful mocking capabilities, allowing developers to easily create mock versions of dependencies or modules. This is particularly useful when testing components or modules that rely on external services or APIs. By mocking these dependencies, developers can isolate the code under test and control the behavior of external dependencies.
Continuous IntegrationJest integrates well with popular continuous integration (CI) systems, such as Jenkins and Travis CI. It provides command-line options and plugins that enable seamless integration with CI pipelines, allowing developers to run tests automatically on each code commit and receive immediate feedback on the test results.
Custom Test EnvironmentJest allows developers to define custom test environments tailored to their specific needs. This is particularly useful when testing applications that require specific configurations or external dependencies. By creating a custom test environment, developers can ensure that their tests accurately simulate the target runtime environment.

TOP 10 Jest Related Technologies

Related Technologies
  • JavaScript

    JavaScript is the most fundamental technology for Jest software development. It is a versatile programming language that allows developers to build interactive web applications. With Jest, JavaScript is used for writing test cases and executing them.

  • TypeScript

    TypeScript is a statically typed superset of JavaScript that adds optional type annotations. It provides better tooling and improves the maintainability of Jest test suites. TypeScript is widely adopted in the Jest community for its type safety and enhanced code readability.

  • React

    React is a popular JavaScript library for building user interfaces. It provides a component-based architecture that promotes reusability and modularity. Jest integrates seamlessly with React, making it the preferred choice for unit testing React components and applications.

  • Vue.js

    Vue.js is another JavaScript framework for developing user interfaces. It has gained significant popularity due to its simplicity and ease of integration with existing projects. Jest supports Vue.js out of the box, making it a reliable choice for testing Vue.js applications.

  • Angular

    Angular is a comprehensive framework for building web applications. It offers a wide range of features and tools for developing large-scale applications. Jest can be used effectively for testing Angular components and services, providing a robust testing solution for Angular projects.

  • Express.js

    Express.js is a minimalist web application framework for Node.js. It simplifies the process of building server-side applications and APIs. Jest can be integrated with Express.js to test the server-side logic and ensure the reliability of the backend code.

  • Redux

    Redux is a predictable state management library for JavaScript applications. It provides a centralized store to manage the application state. Jest can be used to test Redux actions, reducers, and selectors, ensuring the correctness of the state management logic.

Hard skills of a Jest Developer

Hard skills

As a Jest Developer, having a strong set of hard skills is essential for success in the field. Below are the key hard skills required for developers at different levels:

Junior

  • Test Writing: Ability to write clear and concise test cases using Jest framework.
  • Test Execution: Proficiency in executing tests and analyzing the results.
  • Debugging: Skill in identifying and resolving bugs in test cases.
  • Test Automation: Knowledge of automating tests to improve efficiency.
  • Version Control: Familiarity with using Git or other version control systems for code management.

Middle

  • Test Framework Customization: Ability to customize Jest framework to meet specific project requirements.
  • Performance Testing: Experience in testing the performance of applications using Jest.
  • Code Coverage: Knowledge of measuring code coverage to ensure comprehensive testing.
  • Continuous Integration: Proficiency in integrating Jest tests into continuous integration systems.
  • API Testing: Skill in testing APIs using Jest and related libraries.
  • Mocking: Familiarity with mocking external dependencies to isolate tests.
  • Test Data Management: Ability to manage test data effectively for different scenarios.

Senior

  • Test Strategy: Ability to design and implement comprehensive test strategies using Jest.
  • Test Framework Development: Experience in developing custom test frameworks using Jest.
  • Test Environment Setup: Proficiency in setting up complex test environments for Jest.
  • Code Review: Skill in reviewing test code to ensure best practices and maintainability.
  • Performance Optimization: Knowledge of optimizing Jest tests for better performance.
  • Test Reporting: Familiarity with generating detailed test reports using Jest.
  • Integration Testing: Ability to perform integration testing using Jest and related tools.
  • Test Automation Frameworks: Experience with other test automation frameworks and tools.

Expert/Team Lead

  • Test Strategy Planning: Ability to plan and execute test strategies for large-scale projects.
  • Mentoring: Proficiency in mentoring junior developers and providing technical guidance.
  • Test Architecture: Skill in designing and implementing scalable and maintainable test architectures.
  • Test Driven Development (TDD): Experience in driving development through TDD with Jest.
  • Test Framework Selection: Knowledge of selecting the appropriate test frameworks based on project requirements.
  • Test Automation Framework Development: Familiarity with developing custom test automation frameworks using Jest.
  • Performance Testing Optimization: Ability to optimize performance testing processes and tools.
  • Test Coverage Analysis: Skill in analyzing test coverage reports and improving test coverage.
  • Continuous Testing: Proficiency in implementing continuous testing practices using Jest.
  • Test Automation Strategy: Experience in defining and implementing test automation strategies for projects.
  • Technical Leadership: Capability to provide technical leadership and drive the overall testing strategy.

Pros & cons of Jest

Pros & cons

6 Pros of Jest

  • Jest provides a comprehensive testing solution for JavaScript applications, allowing developers to write tests for their code easily and efficiently.
  • It has a simple and intuitive API, making it easy to learn and use for both beginners and experienced developers.
  • Jest has built-in support for popular features like mocking, code coverage, and snapshot testing, which helps developers write more robust and reliable tests.
  • It has excellent performance and speed, thanks to its intelligent test runner that parallelizes test execution, making it ideal for large-scale projects.
  • Jest has great integration with other tools and frameworks, such as Babel, Webpack, and React, making it a popular choice among developers working with these technologies.
  • It has a vibrant and active community, with regular updates and improvements, as well as extensive documentation and resources available online.

6 Cons of Jest

  • Jest can be slower than other testing frameworks when running tests in watch mode, especially for larger codebases.
  • It may require additional configuration and setup for certain use cases, which can be time-consuming for developers who are new to Jest.
  • Jest’s snapshot testing feature can sometimes lead to brittle tests if not used properly, as changes to the code can cause the snapshots to fail and require manual updates.
  • It may not be the best choice for projects that heavily rely on other testing libraries or have complex testing requirements outside of Jest’s capabilities.
  • Jest’s documentation can be overwhelming for beginners, with a vast amount of information that may not be easily digestible or organized in a user-friendly manner.
  • While Jest has good support for JavaScript and React, it may not have the same level of support for other programming languages or frameworks.

What are top Jest instruments and tools?

Instruments and tools
  • Jest: Jest is a JavaScript testing framework developed by Facebook. It was first released in 2014 and has gained popularity among developers due to its simplicity and powerful features. Jest provides a platform for writing unit tests, integration tests, and snapshot tests for JavaScript applications. It offers features like test parallelization, code coverage analysis, and easy mocking of modules and dependencies. Jest is known for its fast and reliable test execution, making it a preferred choice for many developers.
  • Enzyme: Enzyme is a JavaScript testing utility for React applications. It was developed by Airbnb and released in 2015. Enzyme provides a set of APIs that make it easier to test React components. It allows developers to simulate user interactions, traverse and manipulate the component tree, and assert the output of the components. Enzyme is widely used in the React community for testing React components in isolation and ensuring their correct behavior.
  • Puppeteer: Puppeteer is a Node.js library developed by the Chrome team at Google. It provides a high-level API for controlling headless Chrome or Chromium browsers. Puppeteer can be used for various tasks, including web scraping, automated testing, and generating screenshots or PDFs of web pages. With Puppeteer, developers can simulate user interactions, navigate through web pages, and extract data from websites. It is known for its ease of use and powerful capabilities, making it a popular choice for web automation and testing.
  • Cypress: Cypress is a modern JavaScript end-to-end testing framework. It was first released in 2017 and has gained popularity for its simplicity and comprehensive testing capabilities. Cypress allows developers to write tests in a synchronous and intuitive manner, providing real-time reloading and automatic waiting for DOM elements. It also offers features like time-travel debugging, network stubbing, and automatic screenshots and videos of test runs. Cypress is widely used for testing web applications and ensuring their functionality and reliability.
  • React Testing Library: React Testing Library is a lightweight JavaScript testing utility for testing React components. It was developed by Kent C. Dodds and released in 2018. React Testing Library encourages developers to write tests that resemble how a user would interact with the application. It provides a set of simple and intuitive APIs for querying and interacting with the rendered components. React Testing Library focuses on testing the behavior and accessibility of components, ensuring they work as expected for the end users.
  • Jasmine: Jasmine is a behavior-driven development (BDD) JavaScript testing framework. It was first released in 2010 and has been widely adopted in the JavaScript community. Jasmine provides a clean and expressive syntax for writing tests, making it easy to understand and maintain test suites. It includes features like test spies, asynchronous testing support, and built-in matchers for assertions. Jasmine is known for its readability and ease of use, making it a popular choice for testing JavaScript applications.

TOP 10 Facts about Jest

Facts about
  • Jest is a popular JavaScript testing framework created by Facebook.
  • It is widely used for testing JavaScript code, including React applications.
  • Jest provides a simple and intuitive API for writing tests, making it easy for developers to get started with test-driven development.
  • One of the key features of Jest is its ability to run tests in parallel, which can significantly speed up the testing process.
  • Jest comes with built-in code coverage reporting, allowing developers to easily track the percentage of code that is covered by tests.
  • It has a rich set of matchers that make it easy to write assertions and validate the behavior of your code.
  • Jest has powerful mocking capabilities, allowing developers to easily create mock functions and modules to isolate code dependencies during testing.
  • It supports snapshot testing, which enables developers to capture the output of a component or function and compare it against a saved snapshot to ensure that it hasn’t changed unexpectedly.
  • Jest has a watch mode that automatically re-runs tests when files change, making it convenient for iterative development and continuous testing.
  • It integrates seamlessly with other popular JavaScript tools and frameworks, such as Babel, webpack, and ESLint.

Cases when Jest does not work

Does not work
  1. Jest may not work properly if your codebase is not set up correctly. It relies on a specific directory structure and configuration files to run tests. If these are not in place, Jest may not be able to locate and execute your tests effectively.
  2. If your project uses a different testing framework or runner, such as Mocha or Karma, Jest may conflict with them. Jest is designed to be a self-contained testing solution, and integrating it with other frameworks can lead to compatibility issues.
  3. When using certain features or libraries that are not fully supported by Jest, you may encounter problems. For example, if your code relies heavily on native browser APIs or specific DOM implementations, Jest’s default environment may not be sufficient.
  4. Jest may not be suitable for testing large-scale applications with complex dependencies. As your project grows, the sheer number of tests and their interdependencies can impact Jest’s performance and slow down your test suite.
  5. If you are developing a project that requires a high degree of customization, Jest’s configuration options may not cover all your needs. While Jest provides extensive configuration capabilities, there may be certain edge cases where it falls short.

TOP 10 Tech facts and history of creation and versions about Jest Development

Facts and history
  • Jest is a JavaScript testing framework developed and maintained by Facebook.
  • It was first released in 2014 and has since gained popularity for its simplicity and powerful features.
  • Sebastian MarkbÃ¥ge, a software engineer at Facebook, is credited with creating Jest.
  • Jest uses a methodology called “snapshot testing” which allows developers to capture the output of a function or component and compare it against a previously saved snapshot.
  • Snapshot testing helps to catch unintended changes in the output, making it easier to identify and fix bugs.
  • Jest is known for its fast execution speed, thanks to its built-in parallelization and smart test selection features.
  • In 2017, Jest introduced support for running tests in parallel across multiple CPU cores, significantly reducing test execution time.
  • Jest also provides built-in code coverage reporting, allowing developers to measure the effectiveness of their tests.
  • Since its initial release, Jest has undergone several major version updates, introducing new features and improvements.
  • The latest version of Jest, as of 2021, is v27.0.6, which includes enhanced TypeScript support, improved error messages, and better test performance optimizations.

Let’s consider Difference between Junior, Middle, Senior, Expert/Team Lead developer roles.

Seniority NameYears of experienceResponsibilities and activitiesAverage salary (USD/year)
Junior0-2 yearsAssisting in basic programming tasks, bug fixing, code maintenance, learning and improving coding skills, working under the guidance of senior developers.40,000 – 60,000
Middle2-5 yearsDeveloping complex features, participating in code reviews, collaborating with other team members, working on multiple projects, taking ownership of specific modules.60,000 – 90,000
Senior5-10 yearsLeading development efforts, designing and implementing software solutions, mentoring junior developers, making technical decisions, collaborating with cross-functional teams.90,000 – 120,000
Expert/Team Lead10+ yearsLeading a team of developers, setting technical direction, overseeing project execution, providing technical guidance, participating in strategic planning, driving innovation.120,000+

Soft skills of a Jest Developer

Soft skills

Soft skills are essential for a Jest Developer as they contribute to their overall effectiveness and success in their role. Here are the soft skills required for a Jest Developer at different levels:

Junior

  • Attention to Detail: Ability to pay close attention to small details and ensure accuracy in test cases.
  • Collaboration: Willingness to work effectively in a team environment and actively participate in discussions and problem-solving.
  • Communication: Strong verbal and written communication skills to effectively communicate test results and issues to the team.
  • Adaptability: Ability to quickly adapt to changing requirements and priorities in a fast-paced development environment.
  • Problem-Solving: Aptitude for identifying and solving problems in test cases and finding innovative solutions.

Middle

  • Leadership: Ability to take ownership of testing projects, provide guidance to junior developers, and mentor them.
  • Critical Thinking: Strong analytical skills to assess complex scenarios and identify potential issues in test cases.
  • Time Management: Efficiently manage time and prioritize tasks to meet project deadlines and deliver high-quality tests.
  • Negotiation: Skill to negotiate and collaborate with stakeholders to resolve conflicts and ensure smooth testing processes.
  • Quality Assurance: Understanding of quality assurance principles and ability to implement best practices in testing.
  • Attention to Performance: Ability to measure and analyze test performance, identify bottlenecks, and optimize test cases.
  • Customer Focus: Understanding customer requirements and aligning testing efforts to meet their expectations.

Senior

  • Mentorship: Ability to mentor and guide junior and middle-level developers, sharing knowledge and best practices.
  • Strategic Thinking: Capability to think strategically and align testing efforts with overall project goals and objectives.
  • Conflict Resolution: Skill to efficiently resolve conflicts within the team and promote a positive work environment.
  • Decision Making: Confidence in making informed decisions regarding test strategies and approaches.
  • Continuous Improvement: Commitment to continuously improve testing processes and enhance efficiency.
  • Risk Management: Ability to identify and mitigate risks associated with testing and ensure project success.
  • Stakeholder Management: Effective communication and collaboration with stakeholders to ensure testing meets their needs.
  • Innovation: Willingness to explore new tools and technologies to enhance testing practices and efficiency.

Expert/Team Lead

  • Team Management: Ability to lead a team of developers, assign tasks, and ensure timely delivery of high-quality test cases.
  • Project Management: Proficiency in managing testing projects, including planning, resource allocation, and risk assessment.
  • Strategic Planning: Capability to develop long-term testing strategies aligned with business objectives.
  • Technical Expertise: In-depth knowledge of Jest and other testing frameworks, staying updated with industry trends.
  • Collaboration with Stakeholders: Ability to collaborate with stakeholders to understand their requirements and align testing efforts.
  • Performance Optimization: Expertise in optimizing test cases for improved performance and efficiency.
  • Process Improvement: Implementation of process improvements to enhance the overall quality of testing.
  • Problem-Solving at Scale: Ability to identify and address complex testing challenges at a large scale.
  • Decision-Making at Scale: Confidence in making critical decisions that impact the entire testing process.
  • Continuous Learning: Dedication to staying updated with the latest advancements in testing methodologies and tools.
  • Influencing Skills: Ability to influence and inspire the team to achieve testing goals and objectives.

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