Struggling to Mock a Dependency with Multiple Constructors in a Unit Test using Moq and NUnit
I'm wondering if anyone has experience with I'm sure I'm missing something obvious here, but I've been banging my head against this for hours... I am having trouble writing unit tests for a class that has multiple constructors, each accepting different parameters, and I need to mock a dependency using Moq. My class, `MyService`, looks something like this: ```csharp public class MyService { private readonly IDependency _dependency; public MyService(IDependency dependency) { _dependency = dependency; } public MyService(string someParam) { _dependency = new Dependency(someParam); } public string DoWork() { return _dependency.PerformAction(); } } ``` I want to test the `DoWork` method, but since the constructor has two different signatures, I am not sure how to effectively mock `IDependency` when instantiating `MyService`. Here's a snippet of my test: ```csharp [TestFixture] public class MyServiceTests { [Test] public void DoWork_ShouldReturnExpectedResult_WhenDependencyIsMocked() { // Arrange var mockDependency = new Mock<IDependency>(); mockDependency.Setup(d => d.PerformAction()).Returns("Expected Result"); var service = new MyService(mockDependency.Object); // Act var result = service.DoWork(); // Assert Assert.AreEqual("Expected Result", result); } } ``` When I run this test, I get a `NullReferenceException` because the second constructor is being called, which does not use the mocked dependency. I have tried explicitly calling the constructor that takes `IDependency`, but it seems that the test is still defaulting to the second constructor. How can I manage this situation, ideally ensuring that I can test `MyService` without modifying the class itself? Is there a best practice for unit testing classes with multiple constructors in this manner? How would you solve this? I recently upgraded to C# LTS. I'm working in a Linux environment. What are your experiences with this?