Mocking the model and its methods - ruby-on-rails

Question

Can anyone tell me whether my approach is fine?
I want to know the api we are using is working as designed and when it changes so we know that has changed without having to dig through all the code logic. We will provide a set of arguments, we expect a certain result so that my unit tests work well.
User.login({email: username, password: password);
The above method in my model actually hits the API and returns me a response. I want to check whether my Model's login method work as intended.
Below is my approach.
I am stubbing my login method in my model with required params and expected response, to avoid hitting the api and then expecting the login method to derive the same response.
I am using ActiveRestClient.
Below is my model
class User << ActiveRestClient::Base
get :all, '/user'
get :find, '/user/:id'
end
Below is my spec
require 'spec_helper'
describe User do
let(:username) {"test#test.com"}
let(:password) {"123"}
context "when signing in" do
let(:response) {{token: "123"}.to_json}
it "should sign in with valid input" do
allow(User).to receive(:login).with({email: username, password:
password}).and_return(response)
expect(User.login({email: username, password: passwor})).to eq(response)
end
end
end
Can anyone tell me whether my approach is fine?

Answer 1

No, I am sorry, your approach is not fine. Because it does not test a single line of our code. The only thing your spec is testing is that the User.login stub returns what you told it to return.
If you want to speed up your specs by stubbing methods, than you should look for calls in your method that touch the database. Something like User.find_by_email in the following example (And I guess you do something similar in your login method).
Furthermore you may want to spec want happens if the email or the password does not match.
describe User do
describe 'login' do
let(:username) { "test#test.com" }
let(:password) { "password" }
subject(:login) { User.login(email: username, password: password) }
context 'when user do not exists' do
before { allow(User).to receive(:find_by_email).and_return(nil) }
it 'returns nil' do
expect(login).to be_nil
end
end
context 'when user exists' do
before do
allow(User).to receive(:find_by_email).with(username).and_return(user)
end
context 'when password does not match' do
let(:user) { User.new(:password => 'wrong password') }
it 'returns nil' do
expect(login).to be_nil
end
end
context 'when password matches' do
let(:user) { User.new(:password => password, :generate_token => 123) }
it 'returns a json containing the signin token' do
expect(login).to eq "{'token':'123'}"
end
end
end
end
end
Since I have no idea what your login method really does, all specs above are just based on assumptions and will very like not pass with your implementation. But I hope you get the point.