How to stub a method of jasmine mock object?

You have to chain method1, method2 as EricG commented, but not with andCallThrough() (or and.callThrough() in version 2.0). It will delegate to real implementation.

In this case you need to chain with and.callFake() and pass the function you want to be called (can throw exception or whatever you want):

var someObject = jasmine.createSpyObj('someObject', [ 'method1', 'method2' ]);
someObject.method1.and.callFake(function() {
    throw 'an-exception';
});

And then you can verify:

expect(yourFncCallingMethod1).toThrow('an-exception');