RSpec: expect.to receive fails if object is not referenced directly - ruby-on-rails

In my Rails application I have a User model:
class User
def self.foo
User.all.each{ |user| user.bar }
end
def bar
end
end
In my spec file I want to check that foo calls bar for every user, so far that's what I have:
describe '::foo' do
let!(:users) { Fabricate.times(5, :user) }
it 'calls bar for every user' do
users.each do |user|
expect(user).to receive(:bar)
end
User.foo
end
end
Although the method gets called (I debugged it, so I'm sure of that) the spec is red.
Also I tried to write this code to understand where the problem was:
let!(:user) { Fabricate(:user) }
it 'fails' do
expect(user).to receive(:bar)
User.first.bar
end
it 'pass' do
expect(user).to receive(:bar)
user.bar
end
It seems that if I reference my instance directly it works, if I obtain it from the DB the expectation doesn't work.
I use mongoid, not sure if this is relevant.

I believe it cannot be done due to how RSpec works: When you set an expectation, RSpec essentially 'wraps' the object so that it can keep track of the messages it receives.
But when the implementation code fetches records from the database, they are not wrapped, so RSpec isn't able to record their messages.
RSpec does have a method allow_any_instance_of which can help in some cases, but its use is discouraged, and don't think it would be suitable here.
In this situation, I would suggest stubbing User.all to return some doubles (two should be sufficient). You can then verify that bar is called on each one.

Related

RSpec Tests For Method Return & Inheritance

I am trying to write two RSpec tests for two different problems that are much more advanced that what I'm used to writing.
What I'm trying to test within my controller:
def index
#buildings ||= building_class.active.where(place: current_place)
end
My attempt at writing the RSpec test:
describe 'GET :index' do
it "assigns #buildings" do
#buildings ||= building_class.active.where(place: current_place)
get :index
expect(assigns(:buildings)).to eq([building])
end
end
This test failed and wouldn't even run so I know I'm missing something.
My second test is needing to test the returned value of a class method. Here is what I am needing to test within the controller:
def class_name
ABC::Accountant::Business
end
Here is my attempt at testing this method:
describe "class name returns ABC::Accountant::Business" do
subject do
expect(subject.class_name).to eq(ABC::Accountant::Business)
end
end
For the first test I would do something like this:
First, I would move that .active.where(place: current_place) to a scope (I'm guessing building_class returns Building or something like that):
class Building << ApplicationRecord
scope :active_in, -> (place) { active.where(place: place)
Then it's easier to stub for the test
describe 'GET :index' do
it "assigns #buildings" do
scoped_buildings = double(:buildings)
expect(Building).to receive(:active_in).and_return(scoped_buildings)
get :index
expect(assigns(:buildings)).to eq(scoped_buildings)
end
end
Then your controller will do
#buildings ||= building_class.active_in(current_place)
This way you are testing two things: that the controller actually calls the scope and that the controller assigns the returned value on the #buildings variable (you don't really need to test the actual buidlings, you can test the scope on the model spec).
Personally, I feel like it would be better to do something like #buildings = current_place.active_buildings using the same idea of the scope to test that you are getting the active buildings of the current place.
EDIT: if you can't modify your controller, then the stubbing is a little different and it implies some chaining of methods that I don't like to explicitly test.
scoped_buildings = double(:buildings)
controller.stub_chain(:building_class, :active, :where).and_return(scoped_building)
get :index
expect(assings(:buildings)).to eq scoped_buildings
Note that now your test depends on a specific implementation and testing implementation is a bad practice, one should test behaviour and not implementation.
For the second, I guess something like this should work:
describe ".class_name" do
it "returns ABC::Accountant::Business" do
expect(controller.class_name).to eq(ABC::Accountant::Business)
end
end
IMHO, that the method's name if confusing, class_name gives the idea that it returns a string, you are not returnin a name, you are returning a class. Maybe you can change that method to resource_class or something less confusing.

How do you cause an expectation to halt execution in RSpec?

I want to test that a class receives a class-method call in RSpec:
describe MyObject do
it "should create a new user" do
expect(User).to receive(:new)
MyObject.new.doit
end
end
class MyObject
def doit
u = User.new
u.save
end
end
The problem is that the expectation does not halt execution. It simply stubs the class method .doit and continues execution.
The effect of the expectation is to ensure that User.new returns nil. So when we get to the next line which is User.save it then fails because there is no user object to call .save on.
I would like execution to halt as soon as the RSpec expectation has been satisfied - how can I do that?
nb
This is just an illustrative example - while an expect to change would work for User.new, it's not this actual code that I need to test
There is a great method for this and_call_original:
expect(User).to receive(:new).and_call_original
based on your test description, you're testing that a record was created, in those cases I would suggest you to do this:
expect {
MyObject.new.doit
}.to change{User.count}
or if you want to make sure it only created one:
expect {
MyObject.new.doit
}.to change{User.count}.by(1)

FactoryGirl attribute set in after(:create) doesnt persist until referenced?

Sorry for the vague title, there are a lot of moving parts to this problem so I think it will only be clear after seeing my code. I'm fairly sure I know what's going on here and am looking for feedback on how to do it differently:
I have a User model that sets a uuid attr via an ActiveRecord callback (this is actually in a "SetsUuid" concern, but the effect is this):
class User < ActiveRecord::Base
before_validation :set_uuid, on: :create
validates :uuid, presence: true, uniqueness: true
private
def set_uuid
self.uuid = SecureRandom.uuid
end
end
I am writing a functional rspec controller test for a "foo/add_user" endpoint. The controller code looks like this (there's some other stuff like error-handling and #foo and #params being set by filters, but you get the point. I know this is all working.)
class FoosController < ApplicationController
def add_user
#foo.users << User.find_by_uuid!(#params[:user_id])
render json: {
status: 'awesome controller great job'
}
end
end
I am writing a functional rspec controller test for the case "foo/add_user adds user to foo". My test looks roughly this (again, leaving stuff out here, but the point should be obvious, and I know it's all working as intended. Also, just to preempt the comments: no, I'm not actually 'hardcoding' the "user-uuid" string value in the test, this is just for the example)
RSpec.describe FoosController, type: :controller do
describe '#add_user' do
it_behaves_like 'has #foo' do
it_behaves_like 'has #params', {user_id: 'user-uuid'} do
context 'user with uuid exists' do
let(:user) { create(:user_with_uuid, uuid: params[:user_id]) } # params is set by the 'has #params' shared_context
it 'adds user with uuid to #foo' do
route.call() # route is defined by a previous let that I truncated from this example code
expect(foo.users).to include(user) # foo is set by the 'has #foo' shared_context
end
end
end
end
end
end
And here is my user factory (I've tried setting the uuid in several different ways, but my problem (that I go into below) is always the same. I think this way (with traits) is the most elegant, so that's what I'm putting here):
FactoryGirl.define do
factory :user do
email { |n| "user-#{n}#example.com" }
first_name 'john'
last_name 'naglick'
phone '718-555-1234'
trait :with_uuid do
after(:create) do |user, eval|
user.update!(uuid: eval.uuid)
end
end
factory :user_with_uuid, traits: [:with_uuid]
end
end
Finally, The problem:
This only works if I reference user.uuid before route.call() in the spec.
As in, if I simply add the line "user.uuid" before route.call(), everything works as intended.
If I don't have that line, the spec fails because the user's uuid doesn't actually get updated by the after(:create) callback in the trait in the factory, and thus the User.find_by_uuid! line in the controller does not find the user.
And just to preempt another comment: I'm NOT asking how to re-write this spec so that it works like I want. I already know a myriad of ways to do this (the easiest and most obvious being to manually update user.uuid in the spec itself and forget about setting the uuid in the factory altogether). The thing I'm asking here is why is factorygirl behaving like this?
I know it has something to do with lazy-attributes (obvious by the fact it magically works if I have a line evaluating user.uuid), but why? And, even better: is there some way I can do what I want here (setting the uuid in the factory) and have everything work like I intend? I think it's a rather elegant looking use of rspec/factorygirl, so I'd really like it to work like this.
Thanks for reading my long question! Very much appreciate any insight
Your issue has less to do with FactoryGirl and more to do with let being lazily evaluated.
From the docs:
Use let to define a memoized helper method. The value will be cached across
multiple calls in the same example but not across examples.
Note that let is lazy-evaluated: it is not evaluated until the first time
the method it defines is invoked. You can use let! to force the method's
invocation before each example.
Since your test doesn't invoke the user object until the expectation there is nothing created. To force rspec to load object, you can use let!.
Instead of using the before_validation callback you should be using after_initialize. That way the callback is fired even before .valid? is called in the model lifecycle.
class User < ActiveRecord::Base
before_initialization :set_uuid!, on: :create, if: :set_uuid?
validates :uuid, presence: true, uniqueness: true
private
def set_uuid!
# we should also check that the UUID
# does not actually previously exist in the DB
begin
self.uuid = SecureRandom.uuid
end while User.where(uuid: self.uuid).any?
end
def set_uuid?
self.uuid.nil?
end
end
Although the chance of generating the same hash twice with SecureRandom.uuid is extremely slim it is possible due to the pigeonhole principle. If you maxed out in the bad luck lottery this would simply generate a new UUID.
Since the callback fires before validation occurs the actual logic here should be completely self contained in the model. Therefore there is no need to setup a callback in FactoryGirl.
Instead you would setup your spec like so:
let!(:user) { create(:user) }
it 'adds user with uuid to #foo' do
post :add_user, user_id: user.uuid, { baz: 3 }
end

How to deal with stubbing new method with potential Nil class in Ruby and rspec

I have a situation where I stub the .new method of a class, but that makes it to return nil objects, and later those objects are needed, and I am not sure how to deal with it. Here is my rspec code:
describe ShopWorker do
describe '#perform' do
let(:worker) { ShopWorker.new }
it 'creates a new instance of Shopper' do
user = FactoryGirl.create(:user)
expect(Shopper).to receive(:new).with(user)
worker.perform(user.id)
end
end
end
And here is my Worker code:
class ShopWorker
include Sidekiq::Worker
def perform(user_id)
user = User.find(user_id)
shopper = Shopper.new(user)
shopper.start # This fails because Shopper.new returns NIL
end
end
So, since I am stubbing the new method with expect(Shopper).to receive(:new).with(user), then when in the worker it does shopper.start, that is nil, and therefore it breaks. How should I solve this? Ideally, I would like to test that a new instance of Shopper is done and also that the method start is called for that instance.
There are a couple of things you can do:
Expect to receive :new but provide a return value (possibly a mock), using and_return(). The problem is that to receive has an implicit and_return(nil) unless you provide a return value explicitly.
Don't stub :new, let it do its job and expect :start on any Shopper instance: expect_any_instance_of(Shopper).to receive(:start).
Ask yourself what value this test provides. The test knows a lot about the implementation, to a point where you always have to change both. What is the impact of shopper.start? Can you assert anything about the actual business value?

Testing a sweeper with RSpec in Rails

I want to make sure my sweeper is being called as appropriate so I tried adding something like this:
it "should clear the cache" do
#foo = Foo.new(#create_params)
Foo.should_receive(:new).with(#create_params).and_return(#foo)
FooSweeper.should_receive(:after_save).with(#foo)
post :create, #create_params
end
But I just get:
<FooSweeper (class)> expected :after_save with (...) once, but received it 0 times
I've tried turning on caching in the test config but that didn't make any difference.
As you already mentioned caching has to be enabled in the environment for this to work. If it's disabled then my example below will fail. It's probably a good idea to temporarily enable this at runtime for your caching specs.
'after_save' is an instance method. You setup an expectation for a class method, which is why it's failing.
The following is the best way I've found to set this expectation:
it "should clear the cache" do
#foo = Foo.new(#create_params)
Foo.should_receive(:new).with(#create_params).and_return(#foo)
foo_sweeper = mock('FooSweeper')
foo_sweeper.stub!(:update)
foo_sweeper.should_receive(:update).with(:after_save, #foo)
Foo.instance_variable_set(:#observer_peers, [foo_sweeper])
post :create, #create_params
end
The problem is that Foo's observers (sweepers are a subclass of observers) are set when Rails boots up, so we have to insert our sweeper mock directly into the model with 'instance_variable_set'.
Sweepers are Singletons and are instantiated at the beginning of the rspec test. As such you can get to it via MySweeperClass.instance(). This worked for me (Rails 3.2):
require 'spec_helper'
describe WidgetSweeper do
it 'should work on create' do
user1 = FactoryGirl.create(:user)
sweeper = WidgetSweeper.instance
sweeper.should_receive :after_save
user1.widgets.create thingie: Faker::Lorem.words.join("")
end
end
Assuming you have:
a FooSweeper class
a Foo class with a bar attribute
foo_sweeper_spec.rb:
require 'spec_helper'
describe FooSweeper do
describe "expiring the foo cache" do
let(:foo) { FactoryGirl.create(:foo) }
let(:sweeper) { FooSweeper.instance }
it "is expired when a foo is updated" do
sweeper.should_receive(:after_update)
foo.update_attribute(:bar, "Test")
end
end
end

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