HTTP mocking for testing apps: start isolated mock servers, define rich request matchers, template dynamic responses, set invocation expectations, and pool servers to speed tests.
This is a Kotlin Multiplatform line-by-line transliteration port of LukeMathWalker/wiremock-rs.
Original Project: This port is based on LukeMathWalker/wiremock-rs. All design credit and project intent belong to the upstream authors; this repository is a faithful port to Kotlin Multiplatform with no behavioural changes intended.
This is an in-progress port. The goal is feature parity with the upstream Rust crate while providing a native Kotlin Multiplatform API. Every Kotlin file carries a // port-lint: source <path> header naming its upstream Rust counterpart so the AST-distance tool can track provenance.
LukeMathWalker/wiremock-rsThe text below is reproduced and lightly edited from
https://github.com/LukeMathWalker/wiremock-rs. It is the upstream project's own description and remains under the upstream authors' authorship; links have been rewritten to absolute upstream URLs so they continue to resolve from this repository.
wiremock provides HTTP mocking to perform black-box testing of Rust applications that
interact with third-party APIs.
It provides mocking of HTTP responses using request matching and response templating.
The name wiremock is a reference to WireMock.Net, a .NET port of the original Wiremock from Java.
Add wiremock to your development dependencies by editing the Cargo.toml file:
[dev-dependencies]
# ...
wiremock = "0.6"
Or by running:
cargo add wiremock --dev
wiremock provides a set of matching strategies out of the box - check the matchers module
for a complete list.
You can define your own matchers using the Match trait, as well as using Fn closures.
Check Match's documentation for more details and examples.
wiremock empowers you to set expectations on the number of invocations to your Mocks -
check the expect method for more details.
Expectations can be used to verify that a side-effect has (or has not) taken place!
Expectations are automatically verified during the shutdown of each MockServer instance,
at the end of your test. A failed verification will trigger a panic.
By default, no expectations are set on your Mocks.
wiremock lets you specify pre-determined responses using ResponseTemplate and
respond_with.
You are also given the option to have Mocks return different responses based on the matched
Request using the Respond trait.
Check Respond's documentation for more details and examples.
Each instance of MockServer is fully isolated: start takes care of finding a random port
available on your local machine which is assigned to the new MockServer.
To ensure full isolation and no cross-test interference, MockServers shouldn't be
shared between tests. Instead, MockServers should be created in the test where they are used.
When a MockServer instance goes out of scope (e.g. the test finishes), the corresponding
HTTP server running in the background is shut down to free up the port it was using.
wiremock can be used (and it is tested to work) with both async_std and tokio as
futures runtimes.
If you encounter any compatibility bug, please open an issue on our GitHub repository.
wiremock maintains a pool of mock servers in the background to minimise the number of
connections and the time spent starting up a new MockServer.
Pooling reduces the likelihood of you having to tune your OS configurations (e.g. ulimit).
The pool is designed to be invisible: it makes your life easier and your tests faster. If you end up having to worry about it, it's a bug: open an issue!
mockito and httpmock provide HTTP mocking for Rust.
Check the table below to see how wiremock compares to them across the following dimensions:
More request matchers can be added to those provided out-of-the-box to handle common usecases.
stubr for mounting Wiremock json stubs in a MockServer. Also works as a cli.Licensed under either of Apache License, Version 2.0 or MIT license at your option. Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in this crate by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.
dependencies {
implementation("io.github.kotlinmania:wiremock-kotlin:0.1.1")
}
./gradlew build
./gradlew test
See AGENTS.md and CLAUDE.md for translator discipline, port-lint header convention, and Rust → Kotlin idiom mapping.
This Kotlin port is distributed under the same MIT license as the upstream LukeMathWalker/wiremock-rs. See LICENSE (and any sibling LICENSE-* / NOTICE files mirrored from upstream) for the full text.
Original work copyrighted by the wiremock-rs authors.
Kotlin port: Copyright (c) 2026 Sydney Renee and The Solace Project.
Thanks to the LukeMathWalker/wiremock-rs maintainers and contributors for the original Rust implementation. This port reproduces their work in Kotlin Multiplatform; bug reports about upstream design or behavior should go to the upstream repository.
use wiremock::{MockServer, Mock, ResponseTemplate};
use wiremock::matchers::{method, path};
async fn main() {
// Start a background HTTP server on a random local port
let mock_server = MockServer::start().await;
// Arrange the behaviour of the MockServer adding a Mock:
// when it receives a GET request on '/hello' it will respond with a 200.
Mock::given(method("GET"))
.and(path("/hello"))
.respond_with(ResponseTemplate::new(200))
// Mounting the mock on the mock server - it's now effective!
.mount(&mock_server)
.await;
// If we probe the MockServer using any HTTP client it behaves as expected.
let status = reqwest::get(format!("{}/hello", &mock_server.uri()))
.await
.unwrap()
.status();
assert_eq!(status.as_u16(), 200);
// If the request doesn't match any `Mock` mounted on our `MockServer` a 404 is returned.
let status = reqwest::get(format!("{}/missing", &mock_server.uri()))
.await
.unwrap()
.status();
assert_eq!(status.as_u16(), 404);
}
| Test execution strategy | How many APIs can I mock? | Out-of-the-box request matchers | Extensible request matching | API | Spying | Standalone mode |
|---|
| mockito | ✔ Parallel | ✔ Unbounded | ✔ | ❌ | Async/Sync | ✔ | ❌ |
| httpmock | ✔ Parallel | ✔ Unbounded | ✔ | ✔ | Async/Sync | ✔ | ✔ |
| wiremock | ✔ Parallel ️ | ✔ Unbounded | ✔ | ✔ | Async | ✔ | ❌ |
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