Where to find “Microsoft.VisualStudio.TestTools.UnitTesting” missing dll?

Question

I am getting following error in my C# visual studio project:

The type or namespace name \'VisualStudio\' does not exist in the namespace \'Microsoft\'

Answer 1

To resolve this issue, I had to do the following:

1. Launch the Visual Studio Installer with administrative privileges
2. If it prompts you to install updates to Visual Studio, do so before continuing
3. When prompted, click the button to Modify the existing installation
4. Click on the "Individual components" tab / header along the top
5. Scroll down to the "Debugging and testing" section
6. Check the box next to "Web performance and load testing tools"
7. Click the Modify button on the bottom right corner of the dialog to install the missing DLLs

Once the DLLs are installed, you can add references to them using the method that Agent007 indicated in his answer.