Guide to Unit Testing in C# .NET Framework Revit Add-Ins

Unit testing is a valuable practice in software development that allows you to verify the correctness of your code by testing individual units (such as methods or classes) in isolation. When developing Revit add-ins using C# and the .NET Framework, unit testing becomes essential to ensure the reliability and robustness of your extensions. In this guide, we'll explore how to set up and conduct unit tests for your Revit add-ins.

Prerequisites

Before you start unit testing your Revit add-ins, make sure you have the following prerequisites:

Visual Studio: Install Visual Studio or a compatible IDE for C# development.
NUnit Framework: NUnit is a popular unit testing framework for .NET. You can install it via NuGet Package Manager in Visual Studio.
Mocking Framework: Consider using a mocking framework like Moq, NSubstitute, or Rhino Mocks to create mock objects for dependencies.

Setting Up a Unit Test Project

Create a New Unit Test Project:

In Visual Studio, create a new Class Library (.NET Framework) project.
Name it something like "MyRevitAddinTests."

Install NUnit and a Mocking Framework:

In the "Package Manager Console" (Tools -> NuGet Package Manager -> Package Manager Console), run the following commands to install NUnit and a mocking framework (e.g., Moq):

Install-Package NUnit
Install-Package Moq

Configure NUnit:

In your test project, open the "App.config" file and add the NUnit configuration:

<configSections>
  <section name="nunit" type="System.Configuration.NameValueSectionHandler" />
</configSections>
 
<nunit>
  <add key="TestRunner" value="NUnit" />
</nunit>

In the project properties, go to the "Build" tab and select "All configurations" and "Any CPU" as the platform target.

Create Your First Test Class:

In your test project, create a new class for your test cases.

Writing and Running Unit Tests

Now, let's write and run unit tests for your Revit add-in code:

Writing Test Cases:

Create test methods within your test class. These methods should test specific functionality of your add-in code.

[TestFixture]
public class MyAddinTests
{
    [Test]
    public void TestMyMethod()
    {
        // Arrange
        var myAddin = new MyAddin();
 
        // Act
        var result = myAddin.MyMethod();
 
        // Assert
        Assert.AreEqual(42, result);
    }
}

Arrange, Act, Assert (AAA):

In each test method, follow the AAA pattern:
Arrange: Set up the test scenario, create objects, and prepare data.
Act: Invoke the method or code under test.
Assert: Verify the expected results.

Running Tests:

To run your tests, open the Test Explorer in Visual Studio (Test -> Windows -> Test Explorer).
Click "Run All" to execute your tests.

Review Test Results:

Test Explorer displays the results of your tests, indicating whether each test passed or failed.
Investigate failures, fix issues in your code, and rerun the tests until they all pass.

Mocking Dependencies

In Revit add-ins, you may have dependencies on Revit API objects that are difficult to test directly. Mocking frameworks like Moq can help you create mock implementations of these dependencies for testing purposes.

[Test]
public void TestWithMockedDependency()
{
    // Arrange
    var mockRevitDocument = new Mock<Document>();
    mockRevitDocument.Setup(d => d.SomeMethod()).Returns(someValue);
 
    var myAddin = new MyAddin(mockRevitDocument.Object);
 
    // Act
    var result = myAddin.MyMethod();
 
    // Assert
    Assert.AreEqual(expectedResult, result);
}

Conclusion

Unit testing is a critical practice for ensuring the correctness and reliability of your Revit add-ins. By following this guide and leveraging the NUnit framework along with a mocking framework, you can develop robust and maintainable extensions for Autodesk Revit while confidently verifying their behavior through automated tests.

Dependency Injection ASRR.Core