smock-plugin

🎯 SMock - Static & Instance Method Mocking for .NET

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Why SMock?

SMock breaks down the barriers of testing legacy code, third-party dependencies, and static APIs. Built on MonoMod runtime modification technology, SMock gives you the power to mock what others can't.

• Mock Static Methods: The only .NET library that handles static methods seamlessly
• Two API Styles: Choose Hierarchical (with validation) or Sequential (disposable) patterns
• Zero Configuration: Works with your existing test frameworks (NUnit, xUnit, MSTest)
• Complete Feature Set: Async/await, parameter matching, callbacks, exceptions, unsafe code

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Installation

Package Manager

Install-Package SMock

.NET CLI

dotnet add package SMock

💡 Pro Tip: SMock works great with any testing framework - NUnit, xUnit, MSTest, you name it!

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🚀 Quick Start

// Mock a static method in just one line - Sequential API
using var mock = Mock.Setup(() => File.ReadAllText("config.json"))
    .Returns("{ \"setting\": \"test\" }");

// Your code now uses the mocked value!
var content = File.ReadAllText("config.json"); // Returns test JSON

// Or use the Hierarchical API with inline validation
Mock.Setup(() => DateTime.Now, () =>
{
    var result = DateTime.Now;
    Assert.AreEqual(new DateTime(2024, 1, 1), result);
}).Returns(new DateTime(2024, 1, 1));

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Core Concepts

Hook-Based Runtime Modification

SMock uses MonoMod to create runtime hooks that intercept method calls:

• Non-Invasive: No source code changes required
• Isolated: Each test runs in isolation
• Fast: Minimal performance overhead
• Auto-Cleanup: Hooks automatically removed after test completion

Mock Lifecycle

// 1. Setup: Create a mock for the target method
var mock = Mock.Setup(() => DateTime.Now);

// 2. Configure: Define return values or behaviors
mock.Returns(new DateTime(2024, 1, 1));

// 3. Execute: Run your code - calls are intercepted
var now = DateTime.Now; // Returns mocked value

// 4. Cleanup: Dispose mock (Sequential) or automatic (Hierarchical)
mock.Dispose(); // Or automatic with 'using'

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API Styles

SMock provides two distinct API patterns to fit different testing preferences:

Sequential API

Perfect for clean, scoped mocking with automatic cleanup:

[Test]
public void TestFileOperations()
{
    // Mock file existence check
    using var existsMock = Mock.Setup(() => File.Exists("test.txt"))
        .Returns(true);

    // Mock file content reading
    using var readMock = Mock.Setup(() => File.ReadAllText("test.txt"))
        .Returns("Hello World");

    // Your code under test
    var processor = new FileProcessor();
    var result = processor.ProcessFile("test.txt");

    Assert.AreEqual("HELLO WORLD", result);
} // Mocks automatically cleaned up here

Hierarchical API

Perfect for inline validation during mock execution:

[Test]
public void TestDatabaseConnection()
{
    var expectedConnectionString = "Server=localhost;Database=test;";

    Mock.Setup(context => DatabaseConnection.Connect(It.IsAny<string>()), () =>
    {
        // This validation runs DURING the mock execution
        var actualCall = DatabaseConnection.Connect(expectedConnectionString);
        Assert.IsNotNull(actualCall);
        Assert.IsTrue(actualCall.IsConnected);
    }).Returns(new MockConnection { IsConnected = true });

    // Test your service
    var service = new DatabaseService();
    service.InitializeConnection(expectedConnectionString);
}

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⚡ Performance

SMock is designed for minimal performance impact:

• Runtime Hooks: Only active during tests
• Zero Production Overhead: No dependencies in production builds
• Efficient Interception: Built on MonoMod's optimized IL modification
• Benchmarked: Comprehensive performance testing with BenchmarkDotNet

Performance Characteristics