Protocol mocks for Swift 6.3

Strict mocks, checked by the compiler.

Mocksmith generates protocol mocks with Swift macros. There is no Sourcery phase and no generated source to commit.

Get started See compiled examples

Latest release

1.0.0

Published August 14, 2026

Release notes

Package version 1.0.0

One typed workflow

Stub, call, verify.

Attach @Mockable to a protocol. The generated peer keeps test setup tied to the protocol declaration.

WeatherServiceTests.swift

import Mocksmith
import MocksmithTesting

@Mockable
protocol WeatherService {
    func temperature(for city: String) async throws -> Double
}

let weather = WeatherServiceMock()
Given(weather).temperature(for: .value("Toronto")).willReturn(20)

let value = try await weather.temperature(for: "Toronto")
Verify(weather, 1).temperature(for: .value("Toronto"))

Capabilities

Enough control for real test suites

Typed from protocol to assertion

The macro generates the mock and its Given, Perform, Calls, and Verify selectors. Swift checks member names, arguments, and result types.

Strict until you say otherwise

An unstubbed call does not invent a result. Choose per-instance defaults only when a setup-heavy test needs them.

Modern Swift requirements

Mock async and typed-throwing members, actors, generics, static members, subscripts, ownership modifiers, and noncopyable inputs.

Control over time

Return sequences, compute answers from arguments, suspend async calls, capture values, and verify order across mocks.

Call comparison

Assertions use recorded invocations

Every generated mock records its calls. Verify compares that history with typed matchers and a call count. Successful checks mark their calls, so VerifyNoMoreInteractions can catch anything left over.

Recorded call compared with the expectation

Expected

temperature(for: "Toronto")

count: exactly 1

Recorded

temperature(for: "Toronto")

1 matching call

Platform support

Swift 6.3, across Apple and Linux

Apple platforms: iOS 17, macOS 13, tvOS 17, and watchOS 10 or newer
Linux: Supported with the Swift 6.3 toolchain
Swift Testing: Use the MocksmithTesting adapter
XCTest: Use the MocksmithXCTest adapter

Provenance you can inspect

The examples are package tests

The repository's sample target compiles the same public API shown here. Macro tests cover generated declarations, while runtime and integration tests exercise call recording, stubbing, adapters, and inherited protocols.

Read the guides

Start with installation, then move through the module reference.

Read the guide

Open the source

Inspect the package, tests, and executable sample suite on GitHub.

Browse GitHub