how to mock method retry and variable assignment inside method in rspec - ruby-on-rails

Question

require 'requiredclass'
class Test
def get_client()
return some_client
end
def intermediate_method()
res = nil
self.class
.get_client
.retry(tries:5, on: [RequiredClass::ClientTimeout]) do |myclient|
call_count += 1
res = myclient.dosomething()
end
return res
end
def method_to_test()
x = intermediate_method()
y = false
return x && y
end
end
How can I write rspec for method_to_test here. How can I mock get_client.retry as well as calls to get_client while also mocking res variable assignment so that gets assigned the value i would like it to assign.

Answer 1

As written, this code is difficult to test. That's a smell and a sign that the code should be restructured. Really any time you feel tempted to mock a method in the current class, that's a sign that the thing you want to mock does not belong in that class. It should be injected (passed in) instead. Like this:
require 'requiredclass'
class Test
attr_reader :client
def initialize(client)
#client = client
end
def method_to_test
x = intermediate_method
y = false
x && y
end
def intermediate_method
res = nil
client.retry(tries: 5, on: [RequiredClass:ClientTimeout]) do |my_client|
call_count += 1
res = my_client.do_something
end
res
end
end
Given this refactored code, the tests might look like this:
RSpec.describe Test do
subject(:test) { Test.new(client) }
let(:client) { instance_double(Client, retry: true, do_something: true) }
describe '#method_to_test'
subject(:method_to_test) { test.method_to_test }
it 'returns false' do
expect(method_to_test).to be_false
end
end
end
In this code I've passed a double with a stubbed retry method into the Test class on instantiation. You could optionally use a mock, instead. That would look like this:
RSpec.describe Test do
subject(:test) { Test.new(client) }
let(:client) { instance_double(Client) }
before do
allow(client).to receive(:retry)
allow(client).to receive(:do_something)
end
describe '#method_to_test'
subject(:method_to_test) { test.method_to_test }
it 'returns false' do
expect(method_to_test).to be_false
end
end
end
There's a good write up of mocks and doubles in the RSpec documentation.