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HTTP mocking library for Rust.

Build Status codecov Mentioned in Awesome Rust

Documentation · Crate · Report Bug · Request Feature · Changelog


Getting Started

Add httpmock to Cargo.toml:

httpmock = "0.6"

You can then use httpmock as follows:

use httpmock::prelude::*;

// Start a lightweight mock server.
let server = MockServer::start();

// Create a mock on the server.
let hello_mock = server.mock(|when, then| {
        .query_param("word", "hello");
        .header("content-type", "text/html; charset=UTF-8")

// Send an HTTP request to the mock server. This simulates your code.
let response = isahc::get(server.url("/translate?word=hello")).unwrap();

// Ensure the specified mock was called exactly one time (or fail with a detailed error description).

// Ensure the mock server did respond as specified.
assert_eq!(response.status(), 200);

The above example will spin up a lightweight HTTP mock server and configure it to respond to all GET requests to path /translate with query parameter word=hello. The corresponding HTTP response will contain the text body Привет.


See the reference docs for detailed API documentation.


You can find examples in the httpmock test directory. The reference docs also contain a lot of examples. There is an online tutorial as well.

Standalone Mock Server

You can use httpmock to run a standalone mock server that is executed in a separate process. There is a Docker image available at Dockerhub to get started quickly.

The standalone mode allows you to mock HTTP based APIs for many API clients, not only the ones inside your Rust tests, but also completely different programs running on remote hosts. This is especially useful if you want to use httpmock in system or end-to-end tests that require mocked services (such as REST APIs, data stores, authentication providers, etc.).

Please refer to the docs for more information

File Based Mock Specification

For convenience, the standalone mode also allows you to use YAML files for mock specification, so you do not need to use Rust or any other programming language at all. The mock specification file schema is very similar to the httpmock Rust API, so it's easy to jump between the two. Please find an example mock specification file here.

Please refer to the docs for more information.


httpmock is free software: you can redistribute it and/or modify it under the terms of the MIT Public License.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the MIT Public License for more details.