I am new to mocha gem before that I am using minitest to test my product. Then I came across a situation where my application is publishing jobs to facebook. It selects some jobs and then publish them on facebook.
So somebody told me to use mocking and i found mocha gem.
I see a sample test.
def test_mocking_an_instance_method_on_a_real_object
job = Job.new
job.expects(:save).returns(true)
assert job.save
end
But I did not get the idea. In my jobs controller, I have validations
and the empty job cannot be saved successfully. But here with mocking the
above test assert that job can be saved without mandatory fields.So what exactly we test in above test case?
It is a good practice generally for several reasons:
From an isolation point of view: The responsibility of the controller is to handle the incoming request and trigger actions accordingly. In our given case the actions are: create a new Job, and issue a new post to Facebook if everything fits. (Please notice our controller doesn't need to know about how to post to FB)
So imagine the following controller action:
def create
job = Job.new job_params
if job.save
FacebookService.post_job job
...
else
...
end
end
I would test it like:
class JobsControllerTest < ActionController::TestCase
test "should create a job and issue new FB post" do
job_params = { title: "Job title" }
# We expect the post_job method will be called on the FacebookService class or module, and we replace the original implementation with an 'empty/mock' method that does nothing
FacebookService.expects :post_job
post :create, job_params
assert_equal(Job.count, 1) # or similar
assert_response :created
end
end
The other advantage is: FacebookService.post_job might take significant time, and might require internet access etc, we don't want our tests to pending on those, especially if we have CI.
And finally I would test the real FB posting in the FacebookService test, and maybe stub out some other method, to prevent posting on FB every single time when the test runs (it needs time, internet, FB account...).
Related
Perhaps it is my lack of familiarity with rspec but i do not understand what is going on with my test.
I have 2 classes one called Scrape, the other Result (creative) Scrape is a web scraping class that searches a site and scrapes the results from the page, creating a new Result instance from each.
Result instances are stored in a class variable array accessible via Result.all
this works in practice in the actual program, however when I tried to write a test for this behavior it fails.
describe "#scrape_results" do
it "accepts a url scrapes the page and creates a Result for each" do
s = Scrape.new
s.scrape_results(#url)
expect(Result.all.count).not_to eq(0)
end
end
every time i run the test Result.all.count is 0
if i use pry and manually run #scrape_results the test passes.
I appreciate your time, patience, and help
thanks
I notice that you are passing #url to #scrape_results in your test. Unless you are defining that variable inside of the describe block or the test block it will be nil in your test. It is possible that since #url might be something other than nil from wherever you are pry-ing which is causing the Result to be created and the test to pass.
I find mocking things with RSpec to be entirely problematic and I often don't know how much code to include, in terms of it being diagnostic. So I'll start with the situation I have and the code that I've isolated as causing the problem.
I have tests where I need to mock a browser. I have a mock driver I set up like this:
require "watir"
def mock_driver
browser = double("watir")
allow(browser).to receive(:is_a?).with(Watir::Browser).and_return(true)
allow(browser).to receive(:driver).and_return(true)
browser
end
The only problems I have in my test suite are these two tests:
context "an empiric driver is requested" do
it "a watir browser is provided" do
allow(Watir::Browser).to receive(:new).and_return(Empiric.browser)
Empiric.set_browser mock_driver
end
it "the requested watir browser can be shut down" do
#allow(Empiric.browser).to receive(:quit)
Empiric.quit_browser
#allow(mock_browser).to receive(:new).and_return(Empiric.browser)
#Empiric.set_browser mock_driver
end
end
(The commented out bits in the second test are on purpose to illustrate what's going on.)
With that one line in place in the second test, I get the following error on that test:
<Double "watir"> was originally created in one example but has leaked into another
example and can no longer be used. rspec-mocks' doubles are designed to only last for
one example, and you need to create a new one in each example you wish to use it for.
If I entirely comment out the first test above, that error doesn't happen so I know I've isolated the two tests that are interacting with each other.
Okay, now notice the final line of my second test that is commented out. That seems to be what the error is indicating to me. It's saying I need to create a new double in the other. Okay, so I'll change my last test:
it "the requested watir browser can be shut down" do
#allow(Empiric.browser).to receive(:quit)
Empiric.quit_browser
#allow(mock_browser).to receive(:new).and_return(Empiric.browser)
Empiric.set_browser mock_driver
end
So here I've uncommented the last line so I'm establishing the mock_driver in that test and not allowing the code to leak.
That, however, returns exactly the same error on exactly the same test.
I'm not sure if it would help to see the methods that are being called in that test, but here they are. First is set_browser:
def set_browser(app = :chrome, *args)
#browser = Watir::Browser.new(app, *args)
Empiric.browser = #browser
end
And here is quit_browser:
def quit_browser
#browser.quit
end
The fact that RSpec thought one test was "leaking" into the other made me think that perhaps my #browser instance was the problem, essentially being what's persisting between the two tests. But I don't see how to get around that. I thought that maybe if I quit the browser in the first test, that would help. So I changed the first test to this:
it "a watir browser is provided" do
Empiric.quit_browser
allow(Watir::Browser).to receive(:new).and_return(Empiric.browser)
Empiric.start_browser mock_driver
end
That, however, led to the above error being shown on both tests now.
My more likely accurate guess is that I simply don't know how to provide a mock in this context.
I think you have to use allow with the mock and not Watir::Browser.
For example, what happens if you allow the mock browser to receive whatever calls the browser would and have the it return the mock browser?
Right now you're allowing the "Watir::Browser" to receive those messages and that's returning an "Empiric.browser". Looking at your code, I understand why you put that in there but I think that might be what's screwing you up here.
Mocks in RSpec are horrible things that rarely if ever work correctly in situations like this. I would entirely recommend not using the mock_driver that you have set up. Rather, for each of your tests just do something similar to what you are doing in the mock_driver. My guess is you're including the mock driver as part of a shared context and that, too, is another thing that is very fragile in RSpec. Not recommended.
Instead you might want to use contexts to break up your tests. Then for each context block have a before block. I'm not sure if you should use before:all or before:each given that you're simulating a browser. But that way you can set up the browser in the before and tear it down in an after.
But I would recommend getting it working in each test individually first. Even if it's a lot of code duplication. Then once all tests are passing, refactor to put the browser stuff in those before/after blocks.
But, again, don't use mocks. Don't use shared contexts. It never ends well and honestly it makes your tests harder to reason about.
Given some advice from Micah, I wanted to provide an answer with a solution. I ended up doing this:
context "an empiric driver is requested" do
it "a watir browser is provided" do
allow(Watir::Browser).to receive(:new).and_return(Empiric.browser)
allow(Empiric.browser).to receive(:driver).and_return(true)
expect { Empiric.start_browser :some_browser }.not_to raise_error
end
it "the requested watir browser can be shut down" do
allow(Empiric.browser).to receive(:quit)
allow(Watir::Browser).to receive(:new).and_return(Empiric.browser)
allow(Empiric.browser).to receive(:driver).and_return(true)
expect { Empiric.quit_browser }.not_to raise_error
end
end
All of that was needed as it is or I would get some error or other. I removed my mock driver and, per Micah's suggestion, simply tried to incorporate what seemed to work. The above "contraption" is what I ended up with as the sweet spot.
This works in the sense of giving coverage of the methods in question. What was interesting was that I had to add this to my RSpec configuration:
RSpec.configure do |config|
config.mock_with :rspec do |mocks|
mocks.allow_message_expectations_on_nil = true
end
end
I needed to do this because RSpec was reporting that I was calling allowing something that was nil to receive a value.
This brought up some interesting things, if you think about it. I have a test that is clearly passing. And it adds to my code coverage. But is it actually testing the quit action on a browser? Well, not really since it was testing a quit action on something that it thought was nil.
But -- it does work. And it must be calling the lines of code in question because the code coverage, as reported my SimpleCov, indicates that the statements in question have been checked.
I'll be brief with the code samples, as all of my tests pass except the one below. I got it to pass by changing things up a bit, but I'm not sure why version 1 fails and version 2 works.
My model:
# app/models/person.rb
class Person
validates :contact_number, uniqueness: true
end
Model spec
# spec/models/person_spec.rb
require 'spec_helper'
describe Person do
it 'is a valid factory' do
create(:person).should be_valid # passes
end
it 'has a unique phone number' do
create(:person)
build(:person).should_not be_valid # fails
end
it 'also has a unique phone number' do
person1 = create(:person)
person2 = person1.dup
person2.should_not be_valid # passes
end
end
As far as I can tell, the two uniqueness tests should be doing the same thing, however one passes and one fails.
If it matters, I am using mongoid, though I don't think that should have any effect. I'm also not doing anything with nested contexts or describes in my test, so I think the scope is correct. Any insight is appreciated.
UPDATE 1: I realized in my factory I am adding an initialize_with block like this:
initialize_with { Person.find_or_create_by(contact_number: contact_number) }
I realized that this may be the reason the validation was failing -- I was just getting the same person back. However, commenting out that line gives the following error:
Mongoid::Errors::Validations:
Problem:
Validation of Person failed.
Summary:
The following errors were found: Contact number is already taken
Resolution:
Try persisting the document with valid data or remove the validations.
Which, in theory is good, I suppose, since it won't let me save a second person with the same contact number, but I'd prefer my test to pass.
Probably your person factory has a sequence in contact_number making a diferent contact_number in each person.
Just realize that the build(:person) doesnt validate. The validation occurs only in create.
I strongly suggest use of shoulda-matchers for this kind of validations.
It is possible that your database is being cleaned (do you have database-cleaner in your Gemfile), or your tests are not being run in the order you think they are. (Check for :random in your spec_helper.rb)
While the above answer regarding using shoulda-matchers will help you run this particular test in RSpec more concisely, you probably want to have your unique phone number test be able to be run completely on its own without relying on another spec having executed. Your second test is an example of Obscure Test (and also a little bit of Mystery Guest http://robots.thoughtbot.com/mystery-guest), where it's not clear from the test code what is actually being tested. Your phone number parameter is defined in another file (the factory), and the prior data setup is being run in another spec somewhere else in the file.
Your second test is already better because it is more explicitly showing what you're testing, and doesn't rely on another spec having been run. I would actually write it like this to make it more explicit:
it 'has a unique phone number' do
person1 = create(:person, phone_number: '555-123-4567')
person2 = create(:person, phone_number: '555-123-4567')
# can use 'should' here instead
expect(person2).not_to be_valid
end
If you don't explicitly make it about the phone number, then if you change your factory this test might start failing even though your code is still sound. In addition, if you have other attributes for which you are validating uniqueness, your previous test might pass even though the phone number validation is missing.
I figured it out! On a whim, I checked out the test database and noticed that a Person object was lingering around. So, it actually wasn't the
build(:person).should_not be_valid that was raising the Mongoid exception. It was the create call on the line before. Clearing out the DB and running the spec again passed, but again the data was persisting. I double checked my spec_helper.rb file and noticed I wasn't calling start on the DatabaseCleaner. My updated spec_helper.rb file looks like this, and now everything works:
# Clean up the database
require 'database_cleaner'
config.mock_with :rspec
config.before(:suite) do
DatabaseCleaner.strategy = :truncation
DatabaseCleaner.orm = "mongoid"
end
config.before(:each) do
DatabaseCleaner.start
end
config.after(:each) do
DatabaseCleaner.clean
end
Many times one outcome may have two different consequences that need to be tested with a test double. For example if a network connection is successful I'd like to log a message, and also pass the resource to another object that will store it internally. On the other hand it feels unclean to put these two in one test. For example this code fails:
describe SomeClass do
let(:logger) { double('Logger') }
let(:registry) { double('Registry') }
let(:cut) { SomeClass.new }
let(:player) { Player.new }
describe "#connect" do
context "connection is successful" do
it "should log info" do
logger.should_receive(:info).with('Player connected successfully')
cut.connect player
end
it "should register player" do
registry.should_receive(:register).with(player)
cut.connect player
end
end
end
end
I could specify in each test that the function in the other one might get called, but that looks like unnecessary duplication. In that case I'd rather make this one test.
I also don't like that it's never explicit in the test that a method should NOT be called.
Does anyone know about an alternative that has an explicit 'should_not_receive' message instead of automatically rejecting calls that are not explicitly specified?
RSpec supports should_not_receive, which is equivalent to should_receive(...).exactly(0).times as discussed in this message from the original author of RSpec.
I'd like to know about idioms or best practices for testing a multi-step workflow using rspec.
Let's take as an example a "shopping cart" system, where the buying process might be
when user submits to basket and we are not using https, redirect to https
when user submits to basket and we are using https and there is no cookie, create and display a new basket and send back a cookie
when user submits to basket and we are using https and there is a valid cookie and the new item is for a different product than the first item, add a line to the basket and display both lines
when user submits to basket and we are using https and there is a valid cookie and the new item is for the same product as a previous one, increment that basket line's quantity and display both lines
when user clicks 'checkout' on the basket page and is using https and there is a cookie and the basket is non-empty and ...
...
I've read http://eggsonbread.com/2010/03/28/my-rspec-best-practices-and-tips/ which advises i.a that each "it block" should contain only one assertion: instead of doing the computation and then testing several attributes in the same block, use a "before" inside a context to create (or retrieve) the object under test and assign it to #some_instance_variable, then write each attribute test as a separate block. That helps a little, but in a case such as outlined above where testing step n requires doing all the setup for steps [1..n-1] I find myself either duplicating setup code (obviously not good) or creating lots of helper functions with increasingly unwieldy names (def create_basket_with_three_lines_and_two_products) and calling them consecutively in each step's before block.
Any tips on how to do this less verbosely/tediously? I appreciate the general principle behind the idea that each example should not depend on state left behind by previous examples, but when you're testing a multi-step process and things can go wrong at any step, setting up the context for each step is inevitably going to require rerunning all the setup for the previous n steps, so ...
Here's one possible approach -- define an object that creates the necessary state for each step and pass it forward for each successive one. Basically you need to mock/stub the method calls for all the setup conditions:
class MultiStep
def initialize(context)
#context = context
end
def init_vars
#cut = #context.instance_variable_get(:#cut)
end
def setup(step)
init_vars
method(step).call
end
def step1
#cut.stub(:foo).and_return("bar")
end
def step2
step1
#cut.stub(:foo_bar).and_return("baz_baz")
end
end
class Cut # Class Under Test
def foo
"foo"
end
def foo_bar
"foo_bar"
end
end
describe "multiple steps" do
before(:each) do
#multi_stepper = MultiStep.new(self)
#cut = Cut.new
end
it "should setup step1" do
#multi_stepper.setup(:step1)
#cut.foo.should == "bar"
#cut.foo_bar.should == "foo_bar"
end
it "should setup step2" do
#multi_stepper.setup(:step2)
#cut.foo.should == "bar"
#cut.foo_bar.should == "baz_baz"
end
end
Certainly too late for OP, but this could be handy for others - the rspec-steps gem seems to be built for this exact situation: https://github.com/LRDesign/rspec-steps
It might be worthwhile to look at https://github.com/railsware/rspec-example_steps and https://github.com/jimweirich/rspec-given as well. I settled on rspec-steps, but I was in a rush and these other options might actually be better for all I know.