moq

name	moq
description	Creates mock objects and configures test dependencies with Moq. Use when: writing unit tests that need to isolate dependencies, verify method calls, or simulate service behavior.
allowed-tools	Read, Edit, Write, Glob, Grep, Bash

Moq Skill

Moq is the mocking framework used throughout VanDaemon for unit testing. All services are registered as singletons and depend on interfaces, making them ideal candidates for mocking. Tests use Mock<T> to create test doubles, Setup() to configure behavior, and Verify() to assert interactions.

Quick Start

Basic Service Mock

// Mock a service interface
var mockTankService = new Mock<ITankService>();
mockTankService
    .Setup(x => x.GetAllTanksAsync(It.IsAny<CancellationToken>()))
    .ReturnsAsync(new List<Tank> { new Tank { Id = Guid.NewGuid(), Name = "Fresh Water" } });

var controller = new TanksController(mockTankService.Object);

Mock with Argument Matching

var mockControlService = new Mock<IControlService>();
mockControlService
    .Setup(x => x.SetControlStateAsync(
        It.Is<Guid>(id => id != Guid.Empty),
        It.IsAny<object>(),
        It.IsAny<CancellationToken>()))
    .ReturnsAsync(true);

Key Concepts

Concept	Usage	Example
Mock<T>	Create mock instance	new Mock<ITankService>()
.Object	Get mocked instance	mock.Object
Setup()	Configure method behavior	.Setup(x => x.Method())
Returns()	Sync return value	.Returns(value)
ReturnsAsync()	Async return value	.ReturnsAsync(value)
It.IsAny<T>()	Match any argument	It.IsAny<CancellationToken>()
It.Is<T>()	Match with predicate	It.Is<Guid>(g => g != Guid.Empty)
Verify()	Assert method called	.Verify(x => x.Method(), Times.Once)

Common Patterns

Mocking Logger (Serilog via ILogger)

var mockLogger = new Mock<ILogger<TankService>>();
var service = new TankService(mockLogger.Object, mockFileStore.Object);

// Verify logging occurred (Moq can't verify extension methods directly)
// Use LoggerFactory or just trust the implementation

Mocking JsonFileStore

var mockFileStore = new Mock<IJsonFileStore>();
mockFileStore
    .Setup(x => x.LoadAsync<List<Tank>>("tanks.json", It.IsAny<CancellationToken>()))
    .ReturnsAsync(testTanks);

Mocking SignalR Hub Context

var mockHubContext = new Mock<IHubContext<TelemetryHub>>();
var mockClients = new Mock<IHubClients>();
var mockGroup = new Mock<IClientProxy>();

mockHubContext.Setup(x => x.Clients).Returns(mockClients.Object);
mockClients.Setup(x => x.Group("tanks")).Returns(mockGroup.Object);

See Also

• patterns
• workflows

Related Skills

• See the xunit skill for test structure and assertions
• See the fluent-assertions skill for readable assertions
• See the csharp skill for async/await patterns used with mocks