Faking ActiveRecord::Associations::CollectionProxy with Mocha in Capybara (Rails) - ruby-on-rails

I have a very simple data structure: a User has_many filters and a Filter belongs_to a user. For my tests, I am using Capybara, minitest-rails and mocha (no rspec).
I am struggling to adequately stub an ActiveRecord collection of Filters. This is what I have currently:
require 'test_helper'
class TestExample < Capybara::Rails::TestCase
let(:user) { FactoryGirl.create(:user) }
def setup
# Create some mock filters:
f1 = Filter.new
f1.stubs(:id).returns(1)
f1.stubs(:user_id).returns(1)
f1.stubs(:title).returns("First Filter")
f1.stubs(:value).returns(123)
f2 = Filter.new
f2.stubs(:id).returns(2)
f2.stubs(:user_id).returns(1)
f2.stubs(:title).returns("Second Filter")
f2.stubs(:value).returns(456)
fake_filters = [f1, f2]
user.stubs(:filters).returns(fake_filters)
end
def test_user_has_correct_number_of_mocked_filters
assert_equal(user.filters.count, 2)
end
def test_users_mocked_filters_have_correct_ids
assert_equal(user.filters.pluck(:id), [1, 2]) # ERROR
end
end
The second test throws an error, since their is no pluck() method for an Array.
How would this be accomplished? I want the tests to behave as if there are indeed records in the Filter table.

You really shouldn't be mocking objects when using Capybara, it's for full integration/feature tests. Instead you should build them using factory_girl like you are for user
factory :user do
# you current user factory code
# stays here
factory :user_with_filters do
transient do
filters_count 2
end
after(:create) do |user, proxy|
create_list(:filter, proxy.filters_count, user: user)
end
end
end
and then instead of let(:user) { FactoryGirl.create(:user) } do let(:user) { FactoryGirl.create(:user_with_filters) }

Pluck is a method restricted to ActiveRecord::Relation, so unless you also stub a method on fake_filters called pluck, just like you did on Filter
However, what I would do is just use .map(&:id) instead of .pluck(:id). The difference between map and pluck is that map is not efficient during querying since it will do a SELECT * FROM filters instead of SELECT id FROM filters in the case of pluck. Map also allows querying anything the object responds to, not only the active record attributes. However, here, it should be fine.

Related

Should we test rails attributes?

In Rails models we usually have attributes and relations tests, like:
describe 'attributes' do
it { is_expected.to have_db_column(:identifier).of_type(:uuid) }
it { is_expected.to have_db_column(:content).of_type(:jsonb) }
it { is_expected.to have_db_column(:created_at).of_type(:datetime) }
end
describe 'relations' do
it { is_expected.to belong_to(:user).class_name('User') }
end
And using a TDD style it seems to be some useful tests, however I have been dwelling if these are really necessary tests, and I would like to know if there is some common knowledge about it, is it good practice to create these tests? or are we just testing rails?
Amongst the purposes of a unit test are...
Does it work?
Does it still work?
If it's a promise, if other things rely on it, you should test it to ensure you keep that promise. This is regression testing.
But don't test more than you promise. You'll be stuck with it, or your code will break when you make an internal change.
For example...
it { is_expected.to have_db_column(:identifier).of_type(:uuid) }
This promises that it has a column called identifier which is a UUID. Usually you don't promise all that detail; it is glass-box testing and it makes your test brittle.
Instead, promise as little as you can. Its ID is a UUID. This is black-box testing.
require "rspec/uuid"
describe '#id' do
subject { thing.id }
let(:thing) { create(:thing) }
it 'has a uuid ID' do
expect(thing.id).to be_a_uuid
end
end
It's possible there is an even higher level way to express this without holding yourself specifically to a UUID.
it { is_expected.to have_db_column(:content).of_type(:jsonb) }
Similarly, don't promise it has a jsonb column. That is blackbox testing. Promise that you can store complex data structures.
describe '#content' do
subject { create(:thing) }
it 'can round trip complex data' do
data = [1, { two: 3, four: [5] }]
thing.update!(content: data)
# Force it to re-load content from the database.
thing.reload
expect(thing.content).to eq data
end
end
it { is_expected.to belong_to(:user).class_name('User') }
Instead of promising what it belongs to, promise the relationship.
describe '#user' do
let(:thing) { create(:thing) }
let(:user) { create(:user) }
before {
user.things << thing
}
it 'belongs to a user' do
expect(thing.user).to eq user
expect(user.things).to contain(thing)
end
end
I have answered a nearly identical question here: https://stackoverflow.com/a/74195850/14837782
In summary: If it is end-developer code, I believe it should be tested. If it can be fat-fingered, I believe it should be tested. If you're going to remove it deliberately, I also believe you should have to remove a test deliberately as well. If it can fail, there should be a specific test for that failure mode.
This is not to be confused with testing the Rails framework. You obviously want to design your tests so that you're not testing Rails itself or Rails implementation, only your own code.
Attributes should be tested. Here is how I do it in minitest:
test/models/car_test.rb
class CarTest < ActiveSupport::TestCase
###################################################################
#
# Attributes
#
###################################################################
test 'describe some attr_reader fields' do
expected = [:year, :make, :model, :vin]
assert_has_attr_readers(Car, expected)
end
###############################################
test 'describe some attr_writer fields' do
expected = [:infotainment_fimrware_version]
assert_has_attr_writers(Car, expected)
end
###############################################
test 'describe some attr_accessor fields' do
expected = [:owner, :color, :mileage]
assert_has_attr_readers(Car, expected)
assert_has_attr_writers(Car, expected)
end
end
test/test_helpers/attributes_helper.rb
# frozen_string_literal: true
module AttributesHelper
###################################################################
#
# Assertions
#
###################################################################
#
# Performs an assertion that the given class contains reader/getter methods for the given attribute names.
# This helper checks for the existence of `attribute_name` methods on the class, and does not concern itself
# with how those methods are declared: directly defined, attr_reader, attr_accessor, etc.
#
def assert_has_attr_readers(klass, attribute_names)
# Get public and protected method names, passing `false` to exclude methods from super classes.
actual_method_names = klass.instance_methods(false).map(&:to_s)
attribute_names.each do |attribute|
message = "Expected class #{klass.name} to contain a reader for attribute #{attribute}"
assert_includes(actual_method_names, attribute.to_s, message)
end
end
#
# Performs an assertion that the given class contains writer/setter methods for the given attribute names.
# This helper checks for the existence of `attribute_name=` methods on the class, and does not concern itself
# with how those methods are declared: directly defined, attr_writer, attr_accessor, etc.
#
def assert_has_attr_writers(klass, attribute_names)
# Get public and protected method names, passing `false` to exclude methods from super classes.
actual_method_names = klass.instance_methods(false).map(&:to_s)
attribute_names.each do |attribute|
message = "Expected class #{klass.name} to contain a writer for attribute #{attribute}"
assert_includes(actual_method_names, "#{attribute}=", message)
end
end
#
# Performs an assertion that the given class implements attr_encrypted for the given attribute names.
# This helper is tied to the implementation details of the attr_encrypted gem. Changes to how attributes
# are encrypted will need to be accounted for here.
#
def assert_has_encrypted_attrs(klass, attribute_names)
message = "Expected class #{klass.name} to encrypt specific attributes"
actual_attributes = klass.encrypted_attributes.keys
assert_equal(attribute_names.map(&:to_s).sort, actual_attributes.map(&:to_s).sort, message)
end
end
Your example tests seem to be testing the existence of DB fields, not getter/setter model attributes. Database fields are impossible to fat-finger (they require a migration to modify) so if that's what you're talking about, I do not believe it makes sense to test them. (And I personally believe it is useful to test nearly everything.)
Although I guess in the case where the DB is accessible by other applications and could potentially be modified outside of a single application then it could make sense to test for the existence of those fields as well, as pointed out by Dave Newton in a comment below.
Ultimately it is up to you, and if your one application is the only one with access to the DB but you still want to test DB field existence and settings, maybe a 3rd option is some sort of migration test that you're looking for to make sure the migration is written properly. I've not written anything like that yet, but it might be feasible. I would hate to try to write one, and it does seem to go too far, but it's an idea...

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.

RSpec: how to test that parameters are correct in includes().where()

I am new in Rspec testing of Ruby on Rails and I have a question concerning controller tests.
Please, suggest me how to test this line:
#dreams = Dream.public_dreams.includes(:user).where("users.type_id = ?", 5)
In other words, I want to test if correct parameters were set in the controller. It should display all the dreams of a users with type_id equal to 5.
Can someone, please, help me out?
Since you've indicated that you "want to make sure...displayed dreams [are] only of users who have type_id equal to 5", this would seem to me more like a model spec than a controller spec, and I would probably refactor the code and spec it out to look something like this (assuming you still want to keep your rigid conditions):
First, refactor query into a scope in the model:
class DreamsController < ApplicationController
def your_action
#dreams = Dream.public_dreams_for_type_five_users
end
end
class Dream < ActiveRecord::Base
def self.public_dreams
# your code here to access public dreams
end
def self.public_dreams_for_type_five_users
public_dreams.includes(:user).where("users.type_id = ?", 5)
end
end
Next, test the scope in a model spec against some entries in the database that will pass and fail your expectations (the following spec uses FactoryGirl syntax, but you can substitute it out for whatever fixture-substitute library you like):
require 'spec_helper'
describe Dream do
describe ".public_dreams_for_type_five_users" do
let(:type_five_user_public_dreams) { Dream.public_dreams_for_type_five_users }
context "for users where type_id is 5" do
let!(:type_five_dream) { create(:dream, user: create(:user, type_id: 5)) }
it "includes the user's public dreams" do
expect(type_five_user_public_dreams).to include(type_five_dream)
end
end
context "for users where type_id is not 5" do
let!(:type_six_dream) { create(:dream, user: create(:user, type_id: 6)) }
it "does not include the user's public dreams" do
expect(type_five_user_public_dreams).to_not include(type_six_dream)
end
end
end
end
If you wanted, you could then go and further generalise the class method to be something like Dream.public_dreams_for_users_of_type(id) and change the specs accordingly.
There are several answers to that:
You could test the query itself:I would put such a query in a method or scope of your Dream model.Then go and test the query in a model spec.
You could test the assignment:On the other hand you can test the correct assignment in a controller spec with assigns[:dreams]
#dreams.select { |dream| dream.user.type_id = 5 }.should eq(#dreams) ?

Stubbing model attributes in controller tests

I am finding it very hard to stub certain attributes of a model on a controller test. I want to make sure to stub as little as possible.
EDIT: I have been demoved of using stubs for such integration. I understood that the stubs won't reach the action call. The correct question would now be:
How can one use mocks and stubs to simulate a certain state in a Rails controller test?
So I've reached something like the following:
Spec
require 'spec_helper'
describe TeamsController do
let(:team) { FactoryGirl.create :team }
context "having questions" do
let(:competition) { FactoryGirl.create :competition }
it "allows a team to enter a competition" do
post(:enter_competition, id: team.id, competition_id: competition.id)
assigns(:enroll).team.should == team
assigns(:enroll).competition.should == competition
end
end
# ...
end
Factories
FactoryGirl.define do
factory :team do
name "Ruby team"
end
factory :competition, class: Competition do
name "Competition with questions"
after_create do |competition|
competition.
stub(:questions).
and_return([
"something"
])
end
end
factory :empty_competition, class: Competition do
name "Competition without questions"
questions []
after_create do |competition|
competition.stub(:questions).and_return []
end
end
end
Production code
class TeamsController < ApplicationController
def enter_competition
#team = Team.find params[:id]
#competition = Competition.find params[:competition_id]
#enroll = #team.enter_competition #competition
render :nothing => true
end
end
class Team < ActiveRecord::Base
def enter_competition competition
raise Competition::Closed if competition.questions.empty?
enroll = Enroll.new team: self, competition: competition
enroll.save
enroll
end
end
When I run the test, the questions attribute comes as being nil and so the test fails in the model when checking for nil.empty?.
Why isn't the stub being used so that the state of that message is correctly used? I expected that #competition.questions would be [ "question" ] but instead I get nil.
The problem you're running into is that stub works on an instance of a Ruby object; it doesn't affect all ActiveRecord objects that represent the same row.
The quickest way to fix your test would be to add this to your test, before the post:
Competition.stub(:find).and_return(competition)
The reason that's necessary is that Competition.find will return a fresh Competition object that doesn't have questions stubbed out, even though it represents the same database row. Stubbing find as well means that it will return the same instance of Competition, which means the controller will see the stubbed questions.
I'd advise against having that stub in your factory, though, because it won't be obvious what's stubbed as a developer using the factory, and because it means you'll never be able to test the real questions method, which you'll want to do in the Competition unit test as well as any integration tests.
Long story short: if you stub out a method on an instance of your model, you also need to stub out find for that model (or whatever class method you're using to find it), but it's not a good idea to have such stubs in a factory definition.
When you call create on FactoryGirl, it creates database records which you then retrieve back in your controller code. So the instances you get (#team, #competition) are pure ActiveRecord, without any methods stubbed out.
Personally I would write you test like this (not touching database at all):
let(:team) { mock_model(Team) }
let(:competition) { mock_model(Competition) }
before do
Team.stub(:find) { team }
Competition.stub(:find) { competition }
end
and then in your test something like this:
it "should call enter_competition on #team with #competition" do
team.should_receive(:enter_competition).with(competition)
post :enter_competition, id: 7, competition_id: 10
I don't really understand what your controller is supposed to do or what are you testing for that matter, sorry :(

How to test chained methods in Ruby on Rails using Rspec

I'm trying to decide how to test a method that simply calculates an average of values on associated records. I'm concerned about testing the implementation vs the actual result returned.
Say I have the following models...
class User
has_many :interviews
def interview_grade
interviews.average(:score).round unless interviews.empty?
end
end
class Interview
belongs_to :user
end
And in user_spec.rb I have...
describe "interview_grade" do
let(:user) {User.new}
context "when the user has interviews" do
before { user.stub_chain(:interviews, :empty?){false} }
it "should return an average of the appraisal ratings" do
user.interviews.should_receive(:average).with(:score).and_return(3.2)
user.work_history_grade.should == 3
end
end
context "when the user has no interviews" do
before {Interview.destroy_all}
it "should return nil" do
user.interview_grade.should be_nil
end
end
end
These tests pass but it feels fragile to me. What if interview_grade should actually calculate the sum of the scores (for example). As I'm just testing that a particular chain of methods is called, this passing test wouldn't tell me that the result is actually incorrect.
I have tried stubbing user.interviews in order to setup the available scores for the test to work with but this seems tricky to do in Rails 3 due to the way associations are lazy loaded. i.e. I can't just create an array of Interview objects because it doesn't respond to the average method.
Any advice greatly appreciated.
Coming back to this 3 years later. I would would approach it entirely differently.
The benefit of the code below is that in order to write tests for InterviewGrader I would no longer need to worry about how the scores are attained.
I just give it the scores and test it gives me the correct output.
Also I would never need to worry about the underlying implementation of InterviewGrader. However, if the logic was changed at a later date, the tests would fail.
The new scores method on User would need to be tested separately.
class InterviewGrader
def self.run scores
new(scores).run
end
attr_reader :scores
def initialize(scores)
#scores = scores
end
def run
scores.inject { |sum, score|
sum + score
}.to_f / number_of_scores
end
private
def number_of_scores
scores.length
end
end
class User
has_many :interviews
def scores
interviews.map(&:score)
end
def interview_grade
InterviewGrader.run(scores)
end
end
class Interview
belongs_to :user
end
This is incorrect usage of stubbing and mocking.
In this case you should only test, that interview_grade works, when average returns nil (and this is only case interviews.empty? is used).
The average method is tested by rails itself. round method by ruby tests (i guess). So you not need to test this methods. This is a general idea to test only your own code.
And if you want to test, how interview_grade is calculated, you should create test data (with fixtures or factories). Because you should test separate (in some case) part of system, and in this case separation is wrong: interviews.average and interviews.empty? are dependent in your code, but in spec they independent.
def interview_grade
interviews.average(:score).try(:round)
end
If you rewrite your method in this way, you no need in stubbing and mocking

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