How can I pass a parameter to the interface IClassFixture?

Question

I am writing a unit test using xUnit for .Net core.

Below is the TestBase Class

public class TestBase : IDisposable
{
    TestBase(string filename) {
        ...
        stream = new MemoryStream(File.ReadAllBytes(Path.GetFullPath(Path.Combine(Environment.CurrentDirectory, filename))));
    }
    public TestBase() : this("filename.csv") { }            

    public void Dispose() {
        ..
    }
}

Here's how it's being used

public class FileProcessingServiceFacadeTest : IClassFixture<TestBase>
{
    TestBase testBase { get; set; }

    public FileProcessingServiceFacadeTest(TestBase testBase) {
        this.testBase = testBase;
    }

    [Fact]
    public void ProcessAsync() {
        ....
    }
}

Because I don't know how to pass the parameter to the TestBase class using interface IClassFixture, I had to create a constructor that internally calls the parameter constructor.

Can I pass a parameter to interface IClassFixture without an additional constructor?

Removed the `#region`s - please don't do that on either SO or in real life; they add nothing and are a code smell. — Ruben Bartelink, May 30 '22 at 22:44
Is it possible you're looking at tutorials targeted at xUnit 1.x ? https://stackoverflow.com/a/32175366/11635 — Ruben Bartelink, May 30 '22 at 22:51

score 2 · Accepted Answer · answered May 30 '22 at 22:43

Only default constructors are supported for Class (or Collection Fixtures). The main use cases are covered in the docs.

The interface is solely a marker which the test runner uses to know what it needs to create/dispose for a given Test Class. If the constructor on the Test Class asks for the instances, it gets them supplied; if not, that's fine too (they still get created and Disposed)

In other words, the best you can do is to define a base class and then have a concrete derived class that passes down the filename.

How can I pass a parameter to the interface IClassFixture?

1 Answers1