QUnit testing if Error is thrown by method that is being tested

A method of a class I have created is supposed to throw an error under certain circumstances. I have the following:

test('calling do() must throw an error', function(assert) {
  var anInstance = new SomeClass();
  anInstance.do(); 

  /* 
     at this point the above function throws an error 
     that appears on my browser's console with a custom 
     message I am including. What I want to do is verify 
     that this error was actually thrown and if that is the case, 
     consider this test a success. i.e. I want something similar to 
     the below.
   */

   assert.errorWasThrownFromWithinInstanceWithMessage('my custom message');
});

I've looked into assert.throws but it looks like it works with Errors created inside the above scope. I want to check for a specific Error that is thrown from within the instance of my Class which is declared elsewhere on a separate file.