Advanced Unit Testing in .NET Core

Unit testing is an integral part of software development, ensuring that individual units or components of code function correctly. In .NET Core, unit testing is facilitated by various frameworks such as NUnit, MSTest, and xUnit. While basic unit testing ensures that methods and classes behave as expected, advanced unit testing techniques delve deeper into the intricacies of testing complex scenarios, handling edge cases, and maximizing code coverage.

Test Fixture Setup

public class MyTestFixture : IDisposable
{
    private readonly MyService _myService;

    public MyTestFixture()
    {
        // Setup any necessary dependencies
        _myService = new MyService();
    }

    public void Dispose()
    {
        // Cleanup resources
    }

    [Fact]
    public void TestMethod1()
    {
        // Test code
    }
}

Data-Driven Testing

[Theory]
[InlineData(1, "expectedResult1")]
[InlineData(2, "expectedResult2")]
public void TestDataDriven(int input, string expected)
{
    // Arrange

    // Act

    // Assert
}

Mocking Dependencies

public interface IDependency
{
    string GetValue();
}

public class MyClass
{
    private readonly IDependency _dependency;

    public MyClass(IDependency dependency)
    {
        _dependency = dependency;
    }

    public string GetDependencyValue()
    {
        return _dependency.GetValue();
    }
}

public class MyClassTests
{
    [Fact]
    public void TestMyClass()
    {
        // Arrange
        var mockDependency = new Mock<IDependency>();
        mockDependency.Setup(d => d.GetValue()).Returns("mockedValue");
        var myClass = new MyClass(mockDependency.Object);

        // Act
        var result = myClass.GetDependencyValue();

        // Assert
        Assert.Equal("mockedValue", result);
    }
}

Asynchronous Testing

[Fact]
public async Task TestAsyncMethod()
{
    // Arrange

    // Act
    var result = await MyAsyncMethod();

    // Assert
    Assert.NotNull(result);
}

Code Coverage Analysis

Analyzing code coverage helps ensure that tests cover all aspects of the codebase. Tools like dotCover, OpenCover, and Visual Studio’s built-in code coverage analysis can be used to identify untested code paths and improve test suite effectiveness.

Conclusion

Advanced unit testing in .NET Core involves techniques like fixture setup, data-driven testing, mocking dependencies, handling asynchronous code, and code coverage analysis. By applying these techniques effectively, developers can ensure robust test suites that thoroughly validate the functionality and behavior of their code.