Rspec testing Httparty response

I have a definition like this

require 'httparty'
def distance_calculation
    url = "https://api.distancematrix.ai/maps/api/distancematrix/json?origins=# 
    {@departure}&destinations=#{@destination}&key=lugtcyuuvliub;o;o"
    response = HTTParty.get(url)
    distance = response.parsed_response["rows"].first["elements"].first["distance"]. 
    ["text"]

end

End rspec test:

describe "#cargo" do
  context "distance" do
    it "returns hash with destination addresses, origin addresses & rows of datas" do
  end
end

From URL parsing I get hash in which keys are destination_addresses, origin_addresses, distance and duration. How to test by Rspec definition in which the httparty gem is used and, it does not return anything, just writes a parsed field (distance in km) to a variable.

You can stub HTTParty.get method like this working example:

require "rails_helper"

class MyClass
  def distance_calculation
    url = "https://api.distancematrix.ai/maps/api/distancematrix/json?origins=foo&destinations=bar&key=lugtcyuuvliub;o;o"
    response = HTTParty.get(url)
    distance = response.parsed_response["rows"].first["elements"].first["distance"]["text"]
  end
end

RSpec.describe MyClass do
  # you can write some helper methods inside your class test
  def wrap_elements_body(elements)
    {
      rows: [{
        elements: elements
      }]
    }
  end

  def build_distance_body_response(distance)
    item = { distance: { text: distance } }
    wrap_elements_body([item])
  end

  def stub_request_with(body)
    body = JSON.parse(body.to_json) # just to convert symbol keys into string
    response = double(parsed_response: body)

    allow(HTTParty).to receive(:get).and_return(response)
  end


  describe "#cargo" do
    context "distance" do
      it "returns hash with destination addresses, origin addresses & rows of datas" do

        # stubbing 
        expected_distance = 100.0
        body_response = build_distance_body_response(expected_distance)
        stub_request_with(body_response)

        # running 
        calculated_distance = described_class.new.distance_calculation

        # expectations
        expect(calculated_distance).to eq(expected_distance)
      end
    end
  end
end

You can then export those helper methods into a Helper class inside RSpec suite to use in other places.

I like to create these helper methods instead of using https://github.com/vcr/vcr because I can control more what I want and use.