Capybara vs Cucumber: What are the differences?

Introduction:

Capybara and Cucumber are two popular tools used in web application testing. While Capybara is a Ruby library for simulating user interaction with web applications, Cucumber is a tool for behavior-driven development. Although these tools are often used together, they serve different purposes and have some key differences.

1. Programming Language: One key difference between Capybara and Cucumber is the programming language they are based on. Capybara is written in Ruby and primarily used with the Ruby on Rails framework, while Cucumber is a tool that supports multiple programming languages including Ruby, Java, and JavaScript. This means that Capybara is more suited for projects developed in Ruby, whereas Cucumber offers flexibility for teams working with different programming languages.

2. Testing Level: Another difference lies in the level at which these tools operate. Capybara operates at the integration/user interface testing level, meaning it simulates user interactions with the application through a browser-like interface. It focuses on testing the behavior of the entire application from the user's perspective. On the other hand, Cucumber operates at a higher level known as acceptance testing or behavioral testing. It aims to validate the behavior of the application based on defined business requirements or user stories.

3. Syntax and Grammar: Capybara and Cucumber also have distinct syntax and grammar. Capybara uses a domain-specific language (DSL) in Ruby to interact with web elements, perform actions like filling forms or clicking buttons, and make assertions about the expected behavior. Cucumber, on the other hand, uses a plain-text syntax called Gherkin, which is written in a language-agnostic way. Gherkin uses keywords like Given, When, and Then to describe the steps and expected outcomes of scenarios.

4. Specification vs Test Execution: Capybara is mainly used for executing automated tests, focusing on the actual implementation of the test scenarios. It provides a clean and concise way to write tests that interact with the user interface. Meanwhile, Cucumber is more focused on the specification aspect, providing a common language for stakeholders, testers, and developers to collaborate on defining and validating the behavior of the application.

5. Keyword-driven Testing: Capybara largely relies on directly interacting with web elements and performing actions based on element locators, such as searching by CSS selector or XPath. In contrast, Cucumber promotes a keyword-driven approach, where common actions and assertions are encapsulated into reusable steps defined in feature files. This allows for better separation of concerns and promotes readability and maintainability of the test scenarios.

6. Reporting and Documentation: While Capybara provides concise error messages and stack traces to help identify issues in the code, Cucumber goes further by generating human-readable reports in various formats, allowing stakeholders to easily understand the test results. Cucumber's documentation features, such as automated living documentation, are also useful for keeping the application's behavior up-to-date and accessible to non-technical team members.

In summary, Capybara and Cucumber are both valuable tools in web application testing, but they serve different purposes and have distinct features. Capybara focuses on simulating user interactions at the integration level, while Cucumber operates at the acceptance level and emphasizes collaboration and behavior specification. Capybara relies on a Ruby DSL for test implementation, while Cucumber uses Gherkin syntax for defining scenarios. Capybara is more execution-oriented, while Cucumber provides features for documentation and reporting.