Protocol mocks for Swift 6.3
Strict mocks, checked by the compiler.
Mocksmith’s build plugin generates protocol mocks from @Mockable declarations before compilation. 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
Package version 1.0.0
One typed workflow
Stub, call, verify.
Attach @Mockable to a protocol and add MocksmithBuildPlugin to its declaring target. The generated mock 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
Mocksmith 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.
Open the source
Inspect the package, tests, and executable sample suite on GitHub.