Unit Tesing vs E2E Testing

Unit testing and End-to-End(E2E) testing are two distinct levels of software testing, each serving different purposes within the software development lifecycle.

Unit Testing

• Scope: Unit testing focuses on testing individual components or units of code in isolation.
• Purpose: The goal is to verify that each unit of the software performs as designed. Units can be functions, methods, or even entire classes or modules.
• Isolation: Unit tests are isolated from the rest of the system, meaning external dependencies are often mocked or stubbed to ensure that the test is only evaluating the unit itself.
• Development Phase: Typically conducted by developers during the development phase.
• Speed: Unit tests are generally fast to execute since they target small, specific pieces of code.

End-to-End Testing

• Scope: End-to-end testing involves testing the entire application or system from start to finish, simulating real user scenarios.
• Purpose: The goal is to ensure that all integrated components of a system work together as expected and that the application behaves correctly in a real-world environment.
• Isolation: Unlike unit testing, end-to-end tests do not isolate components. They involve testing the complete flow of the application, including user interfaces, backend processes, and interactions with external systems.
• Development Phase: Typically conducted in later stages of development, often during the quality assurance (QA) phase.
• Speed: End-to-end tests can be slower compared to unit tests because they involve a larger portion of the system and may require more setup.

In Angular projects, there are specific tools and libraries commonly used for both unit testing and end-to-end testing. While there are several options available, the two primary frameworks used are Jasmine for unit testing and Cypress for end-to-end testing.

Unit Testing (Jasmine and Karma)

• Jasmine: A behavior-driven development (BDD) testing framework for JavaScript. It provides a clean syntax for writing tests and comes with a set of matchers for assertions.
• Karma: A test runner that works well with Jasmine (and other testing frameworks). Karma is often used to automate the execution of unit tests in various browsers.

To set up unit testing in an Angular project, Angular CLI provides built-in support for Jasmine and Karma. You can use the following commands to generate and run unit tests:

ng test

This command runs the unit tests using Karma and Jasmine.

End-to-End Testing (Cypress)

• Cypress: A JavaScript end-to-end testing framework that is widely used for testing web applications. Cypress provides a simple and powerful API for writing tests and includes features like real-time reloading, automatic waiting, and a time-traveling debugger.

To use Cypress in an Angular project, you can install it as a dev dependency:

npm install cypress --save-dev

After installation, you can open Cypress with:

npx cypress open

Cypress also provides a command-line interface for running tests in CI/CD environments. These libraries and tools work well together to cover both unit testing and end-to-end testing needs in an Angular project.

In summary, unit testing is focused on validating individual units of code in isolation, ensuring that each part of the software functions as intended. End-to-end testing, on the other hand, verifies the entire application’s functionality by testing the integration of various components and simulating user interactions. Both types of testing are essential for ensuring the quality and reliability of software applications.