Rails/Rspec - How to stub a model method inside of a controller test?

Question

I have a controller method that can return different objects at random. How can I stub out the randomization method so that it always returns true or false so I can test the responses?

Example Controller:

class TaskController
  def next 
    if(Tasks.assign_random_test?)
      Tasks.next_test
    else 
      Tasks.next_task
    end
  end
end

ActiveRecord Model:

class Tasks << ActiveRecord::Base
  def self.assign_random_test? 
    rand() > 0.899
  end

  def self.next_test
   # ...
  end

  def self.next_task
   # ... 
  end
end

RSpec Test

RSpec.describe TaskController, type :controller do 
  it 'can return a test task' do 
   # force random method to return true here? 
  end
end

Answer 1

allow(Tasks).to receive(:assign_random_test?).and_return(true)

RSpec.describe TaskController, type :controller do 
  describe '#next' do
    before do
      allow(Tasks).to receive(:assign_random_test?).and_return(true)
    end

    context 'when assign_random_test' do
      it 'should return result' do
        #your test here
      end 
    end

    context 'when not assign_random_test' do
      before do
        allow(Tasks).to receive(:assign_random_test?).and_return(false)
      end
      it 'should return result' do
        #your test here
      end 
    end
  end 
end