Simulate. Test. Verify

A lightweight and expressive library for unit testing in Swift — supporting async/await, delays, error simulation, and call tracking.

Overview

EasyMock is a test utility designed for creating mock objects (test doubles) in Swift with minimal setup and maximum readability.

It’s ideal for testing interactions, async flows, and error handling — without boilerplate.

✨ Features

• ✅ Controlled input/output (stubbing)
• 🔍 Call tracking (spies)
• ⏱ Simulated delays (like network latency)
• 🌀 Full async/await support
• ❗ Error simulation (throw)
• 🧪 Designed for clarity in unit tests

Why Use EasyMock?

Replace This:

final class AuthenticatorMock: Authenticator {
    private(set) var authenticateCallCount = 0
    private(set) var wasCalledWithCredential: Credential?
    var credentialDelay: Double?
    var authenticateStub = makeAnyAuthenticated()
    var authenticateErrorStub: Error?
    
    func authenticate(_ credential: Credential) async throws -> Authenticated {
        if let delay {
            try await Task.sleep(nanoseconds: UInt64(delay * 1_000_000_000))
        }
        
        if let authenticateErrorStub {
            throw authenticateErrorStub
        }
        
        authenticateCallCount += 1
        wasCalledWithCredential = credential
        return authenticateStub
    }
}

With This:

struct AuthenticatorMock: Authenticator {
    let authenticateMocked = AsyncThrowableMock<Credential, Authenticated>(makeAnyAuthenticated())
    
    func authenticate(_ credential: Credential) async throws -> Authenticated {
        try await authenticateMocked.synchronize(credential)
    }
}

Installation

Using Swift Package Manager

Simply add a package to your project passing in https://github.com/EasyPackages/EasySymbol.

In your dependency you can add this in your Package.swift:

dependencies: [
    .package(
        url: "https://github.com/EasyPackages/EasyMock.git",
        from: "1.0.0"
    )
]

In your target:

.target(
    name: "YourApp",
    dependencies: ["EasyMock"]
)

Examples

Basic Mock

let mock = Mock<String, Bool>(true)
let result = mock.synchronize("input")

#expect(mock.spies == ["input"])
#expect(result == true)

AsyncMock

let asyncMock = AsyncMock<Void, String>("Done")
asyncMock.mock(delay: 1.0)

let result = await asyncMock.synchronize()
#expect(result == "Done")

ThrowableMock

enum LoginError: Error { case invalid }

let mock = ThrowableMock<String, Bool>(false)
mock.mock(throwing: LoginError.invalid)

XCTAssertThrowsError(try mock.synchronize("admin"))

AsyncThrowableMock

let asyncMock = AsyncThrowableMock<String, Int>(42)
asyncMock.mock(delay: 0.5)
asyncMock.mock(throwing: nil)

let value = try await asyncMock.synchronize("ping")
XCTAssertEqual(value, 42)

Supported Platforms

• iOS 13+
• macOS 10.15+
• Swift 5.9+

Author

Created by Paolo Prodossimo Lopes
Feel free to contribute, open issues, or suggest improvements.