Unit testing is an essential part of the software development process, allowing developers to verify that individual components of their application work as expected. The .NET Command Line Interface (CLI) provides a straightforward way to run unit tests for an ASP.NET Core application. This guide will walk you through the steps to run unit tests using the CLI.

What are Unit Tests?

Unit tests are automated tests that verify the functionality of a specific section of code, usually at the level of individual functions or methods. They help ensure that changes to the code do not introduce new bugs and that the application behaves as expected.

How to Run Unit Tests Using the CLI

To run unit tests for your ASP.NET Core application using the CLI, follow these steps:

Step 1: Open Your Command Line Interface

Open your terminal (macOS/Linux) or command prompt (Windows) and navigate to the directory containing your test project. This is typically a separate project within your solution that contains your unit tests.

Step 2: Ensure You Have a Test Project

If you do not have a test project yet, you can create one using the following command:

dotnet new xunit -n MyApp.Tests

This command creates a new xUnit test project named MyApp.Tests. You can replace xunit with nunit or mstest if you prefer a different testing framework.

Step 3: Add a Reference to the Project Under Test

If your test project needs to reference the main application project, you can add a reference using the following command:

dotnet add MyApp.Tests/MyApp.Tests.csproj reference MyApp/MyApp.csproj

This command adds a reference to the main application project, allowing the test project to access its classes and methods.

Step 4: Run the Tests

To run the unit tests, use the following command:

dotnet test

This command will build the test project and execute all the tests defined within it. You should see output indicating the results of the tests, including any failures or successes.

Example

Suppose you have a test project named MyApp.Tests and you want to run the tests. You would do the following:

cd MyApp.Tests
dotnet test

After executing this command, you will see output similar to the following:

Test run for MyApp.Tests.dll(.NETCoreApp,Version=v3.1)
    <br>Starting test execution, please wait...
    <br>Passed!  - Failed: 0, Passed: 5, Skipped: 0, Total: 5

This output indicates that all tests have passed successfully.

Running Tests with Specific Options

You can also run tests with specific options, such as filtering tests by name or category. For example, to run tests that contain a specific name, you can use:

dotnet test --filter "Name~MyTest"

This command runs only the tests that have "MyTest" in their name.

Conclusion

Running unit tests for an ASP.NET Core application using the CLI is a straightforward process that helps ensure the reliability of your code. By following the steps outlined in this guide, you can easily create, reference, and run unit tests, allowing you to maintain high-quality code throughout the development process. Understanding how to effectively use the CLI for testing is essential for any .NET developer looking to implement robust testing practices.