it 'instructor should be able to impersonate a user while already impersonating a user but from nav bar' do
      allow(User).to receive(:find_by).with(name: student1.name).and_return(student1)
      allow(User).to receive(:find_by).with(name: student2.name).and_return(student2)
      allow(instructor).to receive(:can_impersonate?).with(student1).and_return(true)
      allow(instructor).to receive(:can_impersonate?).with(student2).and_return(true)