How do I mock HTTP requests in Go unit tests?

Use httpmock's Activate function to intercept requests, then RegisterResponder to define mock responses with helpers like NewStringResponder. It hooks into Go's net/http transport for seamless integration.

httpmock vs gock: which should I use?

httpmock is simpler and integrates well with Go's testing frameworks out-of-the-box, while gock offers more features like request/response recording. Choose httpmock for straightforward mocking with minimal setup.

Can I use httpmock with Ginkgo?

Yes, httpmock works with Ginkgo—activate it in BeforeSuite and reset mocks in BeforeEach, as detailed in the README example. This ensures clean state between test cases.

How to create JSON responses with httpmock?

Use the NewJsonResponder helper to generate JSON responses with application/json content-type, or define custom responder functions to encode Go structs, as shown in the advanced example.

How to check how many times a mock was called?

Call GetTotalCallCount for overall calls or GetCallCountInfo for per-URL details, then use these in assertions with testing frameworks to verify HTTP interaction counts.

httpmock or httptest: when to use which?

Use httptest for creating full HTTP test servers with custom handlers, while httpmock is better for intercepting and mocking requests to external APIs in client code without spinning up servers.

How to mock dynamic responses based on request parameters in httpmock?

Implement a custom responder function that accesses request data via httpmock.MustGetSubmatchAsUint or body decoding, then generate responses dynamically, as demonstrated in the advanced example with regex submatch.

Open-Awesome

httpmock

MITGov1.4.1

A Go library for easy mocking of HTTP responses from external resources in tests.

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2.1k stars106 forks0 contributors

What is httpmock?

httpmock is a Go library for mocking HTTP responses from external APIs and services in tests. It allows developers to isolate their code from network dependencies, enabling faster and more reliable unit tests by simulating API interactions.

Target Audience

Go developers writing unit tests for applications that make HTTP requests to external services, such as REST APIs or third-party integrations.

Value Proposition

Developers choose httpmock for its simplicity, intuitive API, and seamless integration with Go's standard testing package, go-testdeep/tdsuite, and Ginkgo, without adding unnecessary complexity.

Overview

HTTP mocking for Golang

Use Cases

Best For

Unit testing Go applications that depend on external HTTP APIs without making real network calls.
Mocking REST API responses with exact URL matching or regex patterns for flexible test scenarios.
Tracking and verifying HTTP call counts and details during test execution for assertions.
Integrating with testing frameworks like Ginkgo or go-testdeep/tdsuite for structured test suites.
Generating dynamic mock responses based on request parameters using custom handler functions.
Testing HTTP clients, such as those built with Resty, by mocking their transport layer.

Not Ideal For

Projects requiring mocking of non-HTTP protocols like gRPC or WebSockets
Teams needing built-in support for API contract testing with OpenAPI specifications
Applications with complex stateful API simulations that require persistent session management without manual implementation

Pros & Cons

Pros

Flexible URL Matching

Supports both exact URLs and regex patterns, enabling precise or broad mocking scenarios as shown in the simple example with `=~^https://api\.mybiz\.com/articles/id/\d+\z`.

Easy Response Creation

Provides helpers like NewStringResponder and NewJsonResponder to quickly mock responses with custom status codes, headers, and bodies, reducing boilerplate in tests.

Seamless Test Integration

Integrates naturally with Go's standard testing package, go-testdeep/tdsuite, and Ginkgo, with clear examples for each framework in the README.

Call Tracking and Verification

Allows monitoring of HTTP call counts and details via GetCallCountInfo, useful for assertions in unit tests to verify external API interactions.

Cons

Non-Default Client Boilerplate

Requires additional setup for custom HTTP clients like Resty, as shown in the Ginkgo example with ActivateNonDefault, adding complexity and potential for errors.

Limited to HTTP Mocking

Only handles HTTP requests, so projects using other protocols such as gRPC must find separate mocking solutions, increasing dependency management.

No Built-in Concurrency Safety

The README doesn't address thread-safety or handling concurrent requests, which could lead to flaky tests in parallel testing environments.

Frequently Asked Questions

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