Browser Stack , replacing session name with class or test Name

You can use beforeSession.

ex:
beforeSession: function (config, capabilities, specs) { capabilities.name = specs && specs[0].split('/').pop() || undefined; }

selenium testng browserstack

Nunit use below :

capabilities.SetCapability("name", TestContext.CurrentContext.Test.MethodName);

before creating BrowserStack browserit is working for me, for other project checks, how we can SetCapability.

CodeHunter