How to get Angular 2 element through class name in Jasmine

You use By.css to pass a css selector. So any selector you can use with css, you can use with By.css. And a selector for a class is simply .classname (with period).

By.css('.classname')          // get by class name
By.css('input[type=radio]')   // get input by type radio
By.css('.parent .child')      // get child who has a parent

These are just some example. If you know css, then you should know how to use selectors.

EDIT:
To use By.css() be sure to import { By } from '@angular/platform-browser';