gRusticMock

gRusticMock provides gRPC mocking to help you test Rust applications that interact with third-party libraries.

You can concisely describe the request and response expected in your test cases.

Table of Contents

• How to install
• Usage
  • Unary Method
• Test isolation
• Efficiency
• References

How to install

Add gRusticMock to your development dependencies by editing the Cargo.toml file:

[dev-dependencies]
# ...
gRusticMock = "0.1"

Or by running:

cargo add wiremock --dev

Usage

Unary Method

use grusticmock::{MockServer, Mock, ResponseTemplate};
use grusticmock::matchers::{method, path};

#[async_std::main]
async fn main() {
    // Start a background HTTP server on a random local port
    let mut mock_server = MockServer::start().await;

    let expected := Item { "id": 42, "name": "Item 42" }

    // Arrange the behaviour of the MockServer:
    mock_server
        .expect_unary("myservice/getItems")
        .with_header("locale", "en-US")
        .with_payload(AnyRequest {"id": 42})
        .return(&expected);
    
    // ToDo: Fix me to real code
    let response = tonic::unary(
        mock_server.address,
        "myservice/getItems",
        AnyRequest {"id": 42},
    )
        .header("locale", "en-US")
        .insecure()

    assert_eq!(matches!(Ok(expected), response))

Test isolation

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.

Efficiency

gRusticMock maintains a pool of mock servers in the background to minimise the number of connections and the time spent starting up a new MockServer.

References

This repository was inspired by:

• wiremock-rs for HTTP mocking to test Rust applications.
• grpcmock for gRPC mocking to test Go applications.