Component testing
Component testing evaluates an individual software component’s behavior at its boundaries, independently of the wider system while allowing relevant interactions with dependencies.
BDD in Action, Second Edition
A component test evaluates an individual software component or UI component in isolation from parts of the wider system.
- How it is used
- Applies isolated UI checks when full-system assembly adds cost without improving confidence in the behavior under test.
- How deep it goes
- Explains isolation and test-boundary choices with registration scenarios, but stops short of detailed component-test implementation.
- Examples
- Uses registration-field validation, terms acceptance, mocked services, Storybook, and Playwright Component Tests as examples.
- What you can do after
- Apply it via Storybook or Playwright Component Tests to verify UI behavior without deploying the entire system.
Read how BDD in Action, Second Edition explains component testing →
Web Components in Action
Component testing is the practice of verifying a reusable interface component's behavior, rendering, and public API in isolation.
- How it is used
- Verifies Web Component behavior, rendering, and public APIs through browser-run tests.
- How deep it goes
- Builds fixtures, suites, assertions, and boundary tests without descending into browser automation internals.
- Examples
- Uses a slider fixture to test initial values, JavaScript setters, rendered thumb position, and min/max clamping.
- What you can do after
- Apply it via Web Component Tester, Mocha, and Chai to run component tests in automated browsers.
Read how Web Components in Action explains component testing →
Build Financial Software with Generative AI (From Scratch)
Component testing is testing that evaluates an isolated software component, such as an API, independently of other components.
- How it is used
- Evaluates an API independently to catch malformed requests and exception conditions.
- How deep it goes
- Demonstrates endpoint assertions and BDD structure, while deferring broader testing categories and detailed implementation.
- Examples
- Uses a FastAPI /files endpoint, TestClient assertions, and a BDD feature with step definitions.
- What you can do after
- Apply it via FastAPI TestClient to verify endpoint status codes and response data.
Read how Build Financial Software with Generative AI (From Scratch) explains component testing →
Related concepts
- testkind of · A test is a procedure or check that evaluates behavior using specified inputs or evidence against expected results or criteria.
- React Testing Libraryused by · React Testing Library is a JavaScript library for testing React components through their rendered behavior, user-facing interactions, and accessible interfaces.
- system-level verificationcontrasts with · System-level verification evaluates the behavior and interactions of multiple software components assembled into a complete or substantially complete system.
- integration testcontrasts with · An integration test evaluates whether multiple software components, or a component and an external dependency, interact and behave correctly together.
- browserused by · A web browser is software that retrieves, interprets, and renders web resources, executes supported web content, and enables interaction with web pages and applications.
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