RSpec Stubbing out Date.today in order to test a method

Question

I want to test a method that follows one path if the current date is between Jan 1st - Aug 1st, or it follows another path if the current date is between Aug 2nd - December 31st. example:

def return_something_based_on_current_date
  if date_between_jan_1_and_aug_1?
    return "foo"
  else 
    return "bar"
  end
end

private

def date_between_jan_1_and_aug_1?
  date_range = build_date_range_jan_1_through_aug_1
  date_range === Date.today
end

def build_date_range_jan_1_through_aug_1
  Date.today.beginning_of_year..Date.new(Date.today.year, 8, 1)
end

As you can see: return_something_based_on_current_date depends heavily upon Date.today , as does the private methods it invokes. This is making it difficult to test both paths within this method since Date.today dynamically returns the current date.

For testing purposes: I need Date.today to return a static date that I want it to so that I can test that each path is working correctly.

• I need to test that the path works correctly if the current date is between Jan 1 - Aug 1
• I need to test that the path works correctly if the current date is after Aug 1st.

Question : Is there a way that I can make Date.today return a value that I make up within my spec? After the specs that test the return_something_based_on_current_date : I want the dynamic implementation of Date.today to go back to its usual implementation. I just need control over Date.today to test this method.

Answer 1

Add this to your before block .

allow(Date).to receive(:today).and_return Date.new(2001,2,3)

I *think* it is not necessary to unstub.

Answer 2

I recommend you look at the Timecop gem, it allows to freeze the time at a given date.

On top of stubbing the current Time, it also allows to travel in time for a given test

https://github.com/travisjeffery/timecop

describe "some set of tests to mock" do
  before do
    Timecop.freeze(Time.local(1990))
  end

  after do
    Timecop.return
  end

  it "should do blah blah blah" do
  end
end

Update

As Andy mentions in the comments, there is a helper method travel_to available since Rails 4.1

Reference is available here: http://api.rubyonrails.org/classes/ActiveSupport/Testing/TimeHelpers.html

Answer 3

There's another approach you might want to consider, that doesn't require any stubbing – change the public method to accept an argument for the current date.

Clarification:

Change def return_something_based_on_current_date to def return_something_based_on_current_date(current_date) , then change all instances of Date.today to current_date . You'll also need to pass current_date into the private methods.

Then in your tests, you can pass whatever you want as current_date .

Answer 4

I was in a similar situation but I didn't want to install the gem. as I was interested in time intervals bigger than one day so I decided to do it this way

it 'Creates an event for tomorrow' do
  event = FactoryBot.create(:event, :tomorrow)
  expect(event.date.day).to eq (Time.now + 1.day).day
end

it 'Creates an event for the next week' do
  event = FactoryBot.create(:event, :next_week)
  expect(event.date.day).to eq (Time.now + 1.week).day
end

it 'Creates an event for the next month' do
  event = FactoryBot.create(:event, :next_month)
  expect(event.date.day).to eq (Time.now + 1.month).day
end

so I just tested the expected date, I am afraid that there is a specific time of the day that the test will be broken but I don't care

Answer 5

Since Rails 4.2 there's the ActiveSupport::Testing::TimeHelpers module that provides a straightforward way to do this:

travel_to(Time.parse("2019-01-19")) do
  # your code here
end