nock/nock
Nock
nock is a Node.js HTTP mocking library and request interceptor. It captures outgoing network traffic to specific hosts and paths, returning predefined responses to decouple applications from external servers during automated testing.
The project functions as an API expectation framework to verify that specific calls were made with correct parameters. It includes a traffic recorder that captures real network interactions as fixtures for playback and a network simulation tool to introduce artificial latency or trigger network errors.
Its capabilities cover request matching via hostnames, paths, and headers, as well as the management of mock lifecycles. The tool provides outbound request control to block all outgoing traffic except for specifically allowed hostnames.
Features
- Network Request Interceptors - Intercepts outgoing HTTP requests to redirect traffic to predefined mock responses instead of a live server.
- HTTP Mocking - Intercepts outgoing HTTP requests in Node.js to return predefined responses, decoupling application logic from external servers.
- Request Matching - Matches requests using hostnames, paths, verbs, or headers through strings and regular expressions.
- Request Matchers - Evaluates a collection of defined mock patterns against every intercepted HTTP call to determine the response.
- API Response Simulators - Defines return status codes and response bodies using strings, JSON, or callbacks to simulate API behavior.
- HTTP Mocking Libraries - Provides a comprehensive library for intercepting outgoing HTTP requests and returning predefined responses in Node.js.
- API Expectation Frameworks - Functions as a framework to verify that specific HTTP calls were made with correct parameters and headers.
- API Integration Testing - Enables verification that an application sends correct HTTP requests and handles various server responses within automated suites.
- HTTP Interaction Recording - Captures real HTTP interactions as fixtures to replay them for deterministic offline testing.
- Mock Interaction Recorders - Captures real network interactions as fixtures to be replayed in future test runs.
- API Request Mocking - Intercepts network requests to simulate server responses and decouple code from external dependencies.
- HTTP Interaction Recorders - Captures real network interactions as fixtures that can be replayed in future test environments.
- Request Interception and Blocking - Captures outgoing calls to specific hosts and paths to return predefined responses instead of contacting live servers.
- HTTP Request Interceptors - Captures outgoing network traffic to specific hosts and paths to prevent calls to live external servers.
- Network Access Control - Blocks all outgoing HTTP requests to non-mocked hosts or allows specific hostnames to bypass the interceptor.
- Outbound Network Blockers - Blocks all outgoing network traffic except for specifically allowed hostnames to prevent accidental external API calls during tests.
- Error Simulation Utilities - Introduces artificial latency and triggers network errors to test how the application handles failures.
- Dynamic Response Callbacks - Provides the ability to use JavaScript functions to generate dynamic, request-aware mock responses.
- Mock State Resetting - Provides utilities for removing specific interceptors or clearing all active mocks to reset the test environment.
- Request Verification - Inspects properties of outgoing requests to ensure they meet expected parameters and specifications.
- Network Connectivity Controls - Restrict connections to specific hostnames to prevent accidental external network requests during testing.
- Network Outbound Blocklists - Prevents accidental external network calls by blocking all outgoing traffic that does not match a mock.
- Network Resilience Simulators - Introduces artificial latency and triggers network errors to verify application timeout and failure handling.
- Response Simulators - Returns custom status codes and headers with timing delays to mimic various server response behaviors.
- Lifecycle Management - Clears interceptors and restores original network behavior to reset the environment between test scenarios.
- State Expectation Validation - Maintains a queue of pending requests to verify that specific API calls were made before tests complete.
- Test-Frameworks - HTTP server mocking and request expectations.
