Add NUnit Test Adapter
MODIFY
sample-code/csharp/test/packages.config
sample-code/csharp/test/packages.config
<package id="Castle.Core" version="4.3.1" targetFramework="net47" />
<package id="Newtonsoft.Json" version="11.0.2" targetFramework="net47" />
<package id="NUnit" version="3.10.1" targetFramework="net47" />
+ <package id="NUnit3TestAdapter" version="3.11.0" targetFramework="net47" />
<package id="Selenium.Support" version="3.8.0" targetFramework="net47" />
<package id="Selenium.WebDriver" version="3.8.0" targetFramework="net47" />
</packages>
\ No newline at end of file

Add NUnit Test Adapter