I've just started to take on my first model spec task at work. After writing a lot of feature specs, I find it hard to get into the different perspective of writing model specs (not taking the context into consideration). I'll take a method of the Order model as an example, to explain which difficulties I am experiencing:
def update_order_prices
self.shipping_price_cents = SHIPPING_PRICE_CENTS unless shipping_price_cents
return if order_lines.empty?
self.total_price_cents = calculate_order_price
self.total_line_items_price_cents = calculate_total_order_line_price
self.total_tax_cents = calculate_tax_amount
end
EDIT TL;DR
I am totally happy with an answer that simply writes me a spec for this method. The rest of the post just shows what I tried so far but is not necessary to answer this question.
First approach:
At first I didn't know what to test for. I tried to find out when and where the method was called and to find a scenario where I would know what the attributes that are touched in this method should be equal to. Put short, I spent a lot of time trying to understand the context. Then a coworker said that I should test methods in model specs self-contained, independent from the context. I should just make sure I identify all cases. So for this method that would be:
it sets shipping price cents to default (if not done already)
it returns early if order_lines is empty
it sets values if order_line is set
Current approach:
I tried writing the tests for these points but still questions arise:
Test 1
it 'sets shipping price cents to default (if not done already)' do
order.shipping_price_cents = nil
order.update_order_prices
expect(order.shipping_price_cents).to eq(Order::SHIPPING_PRICE_CENTS)
end
I am confident I got this one right, but feel free to prove me wrong. I set shipping_price_cents to nil to trigger the code that sets it, call the tested method on the cents to be equal to the default value as defined in the model.
Test 2
it 'returns early if order_lines is empty' do
expect(order.update_order_prices).to eq(nil)
end
So here I want to test that the method returns early when there is no object in the order_lines association. I didn't have a clue how to do that so I went into the console, took an order, removed the order_lines associated with it, and called the method to see what would be returned.
2.3.1 :011 > o.order_lines
=> #<ActiveRecord::Associations::CollectionProxy []>
2.3.1 :012 > o.update_order_prices
=> nil
Then did the same for an order with associated order_line:
2.3.1 :017 > o.update_order_prices
=> 1661
So I tested for 'nil' to be returned. But it doesn't feel like I am testing the right thing.
Test 3
it 'sets (the correct?) values if order_line is set' do
order_line = create(:order_line, product: product)
order = create(:order, order_lines: [order_line])
order.update_order_prices
expect(order.total_price_cents).to eq(order.calculate_order_price)
expect(order.total_line_items_price_cents).to eq(order.calculate_order_line_price)
expect(order.total_tax_cents).to eq(order.calculate_tax_amount)
end
I simply test that the attributes equal what they are set to, without using actual values, as I shouldn't look outside. If I wanted to test for an absolute value, I would have to investigate outside of this function which then wouldn't test the method but also status of the Order object etc.?
Running the tests
Failures:
1) Order Methods: #update_order_prices sets (the correct?) values if order_line is set
Failure/Error: expect(order.total_price_cents).to eq(order.calculate_order_price)
NoMethodError:
private method `calculate_order_price' called for #<Order:0x007ff9ee643df0>
Did you mean? update_order_prices
So, the first two tests passed, the third one didn't. At this point I feel a bit lost and would love hear how some experienced developers would write this seemingly simple test.
Thanks
I guess you have to spec against the exact values you are expecting after update_order_prices.
Let's say you set up your order and order lines to have a total price of 10 euros then I'd add the following expectation
expect(order.total_price_cents).to eq(1000)
Same for the other methods. Generally I try to test against specific values. Also as you are relying on the result of a private method you only care about the result.
Related
Using Mocha on Rails 4.2.
I'm testing a method that it should make a call to another method with the correct parameters. These parameters are ActiveRecord objects that it calls up from the database. Here is the key line in my test:
UserMailer.expects(:prompt_champion).with(users(:emma), [[language, 31.days.ago]]).once
Both users(:emma) and language are ActiveRecord objects.
Even though the correct call is made, the test fails because the parameters don't match the expectations. I think this might be because it's a different Ruby object each time a record is pulled up from the database.
I think one way around it is to see what method is being used in my code to pull up the records and stub that method to return mocks, but I don't want to do this because a whole bunch of Records are retrieved then filtered down to get to the right one, mocking all those records would make the test way too complex.
Is there a better way of doing this?
You could use block form of allow/expect.
expect(UserMailer).to receive(:prompt_champion) do |user, date|
expect(user.name).to eq "Emma"
expect(date).to eq 31.days.ago # or whatever
end
Sergio gave the best answer and I accepted it. I discovered the answer independently and found out along the way that I needed to return a mock from the ActionMailer method to make everything work properly.
I think it best to post here my complete test here for the sake of any other hapless adventurer to come this way. I'm using Minitest-Spec.
it 'prompts champions when there have been no edits for over a month' do
language.updated_at = 31.days.ago
language.champion = users(:emma)
language.save
mail = mock()
mail.stubs(:deliver_now).returns(true)
UserMailer.expects(:prompt_champion).with do |user, languages|
_(user.id).must_equal language.champion_id
_(languages.first.first.id).must_equal language.id
end.once.returns(mail)
Language.prompt_champions
end
You could use an RSpec custom matcher and compare expected values in that function.
It said here https://www.relishapp.com/rspec/rspec-core/v/3-5/docs/helper-methods/let-and-let what variable defined by let is changing across examples.
I've made the same simple test as in the docs but with the AR model:
RSpec.describe Contact, type: :model do
let(:contact) { FactoryGirl.create(:contact) }
it "cached in the same example" do
a = contact
b = contact
expect(a).to eq(b)
expect(Contact.count).to eq(1)
end
it "not cached across examples" do
a = contact
expect(Contact.count).to eq(2)
end
end
First example passed, but second failed (expected 2, got 1). So contacts table is empty again before second example, inspite of docs.
I was using let and was sure it have the same value in each it block, and my test prove it. So suppose I misunderstand docs. Please explain.
P.S. I use DatabaseCleaner
P.P.S I turn it off. Nothing changed.
EDIT
I turned off DatabaseCleaner and transational fixtures and test pass.
As I can understand (new to programming), let is evaluated once for each it block. If I have three examples each calling on contact variable, my test db will grow to three records at the end (I've tested and so it does).
And for right test behevior I should use DatabaseCleaner.
P.S. I use DatabaseCleaner
That's why your database is empty in the second example. Has nothing to do with let.
The behaviour you have shown is the correct behaviour. No example should be dependant on another example in setting up the correct environment! If you did rely on caching then you are just asking for trouble later down the line.
The example in that document is just trying to prove a point about caching using global variables - it's a completely different scenario to unit testing a Rails application - it is not good practice to be reliant on previous examples to having set something up.
Lets, for example, assume you then write 10 other tests that follow on from this, all of which rely on the fact that the previous examples have created objects. Then at some point in the future you delete one of those examples ... BOOM! every test after that will suddenly fail.
Each test should be able to be tested in isolation from any other test!
I'm using the cancan gem, and in ability.rb, I wanted to check if a user with a certain role can update another object if and only if the user 'is part of' the other object (that is, there is an association between the models, and the user is found in the object's users method).
I wanted to use the include? method to see if #current_user is found in the resulting User array.
It always returns false when testing the code through ability.rb. If I run the same code in the rails console, it works fine.
I found out that include? does not work if the Array objects are not of the same class as the passed object, but I printed their class through class.name, and they are the same.
I ended up using detect and comparing id's, but I wanted to know if anyone has had this kind of issue before, and if you could shed some light on this.
Something similar happened with delete_if, where after deleting 20 out of a 100, count was still returning 100, but an each loop printed only the ones that were supposed to be there (20). This happened when executing within the RoR environment, but the rails console with the same code behaved as expected (array.count # => 20).
EDIT 20131007
A bit of code regarding the include? issue.
This bit returns false all the time, even though the user IS in the resulting array from course.institution.users.
can [:read, :update], Course do |course|
val = course.institution.users.include? user
end
If I take that same line, and try it for a given course and user in the rails console, like so:
Course.find(course_id).institution.users.include? User.find(user_id)
It works as it's supposed to, returning true then the user is found in the array and false if not.
So even, even if the == operator was weird in some way for this particular model, I'm dealing with the same arrays in both cases, so it should either bust or work well in both cases, not only within the cancan ability.rb... right?
Cancan has a built-in mechanism to query associations. Without knowing your exact setup, this should be close to how you could set this up in your Ability class:
can :view, MyObject, users: { id: user.id }
I'm writing an application that allows users to send one another messages about an 'offer'.
I thought I'd save myself some work and use the Mailboxer gem.
I'm following a test driven development approach with RSpec. I'm writing a test that should ensure that only one Conversation is allowed per offer. An offer belongs_to two different users (the user that made the offer, and the user that received the offer).
Here is my failing test:
describe "after a message is sent to the same user twice" do
before do
2.times { sending_user.message_user_regarding_offer! offer, receiving_user, random_string }
end
specify { sending_user.mailbox.conversations.count.should == 1 }
end
So before the test runs a user sending_user sends a message to the receiving_user twice. The message_user_regarding_offer! looks like this:
def message_user_regarding_offer! offer, receiver, body
conversation = offer.conversation
if conversation.nil?
self.send_message(receiver, body, offer.conversation_subject)
else
self.reply_to_conversation(conversation, body)
# I put a binding.pry here to examine in console
end
offer.create_activity key: PublicActivityKeys.message_received, owner: self, recipient: receiver
end
On the first iteration in the test (when the first message is sent) the conversation variable is nil therefore a message is sent and a conversation is created between the two users.
On the second iteration the conversation created in the first iteration is returned and the user replies to that conversation, but a new conversation isn't created.
This all works, but the test fails and I cannot understand why!
When I place a pry binding in the code in the location specified above I can examine what is going on... now riddle me this:
self.mailbox.conversations[0] returns a Conversation instance
self.mailbox.conversations[1] returns nil
self.mailbox.conversations clearly shows a collection containing ONE object.
self.mailbox.conversations.count returns 2?!
What is going on there? the count method is incorrect and my test is failing...
What am I missing? Or is this a bug?!
EDIT
offer.conversation looks like this:
def conversation
Conversation.where({subject: conversation_subject}).last
end
and offer.conversation_subject:
def conversation_subject
"offer-#{self.id}"
end
EDIT 2 - Showing the first and second iteration in pry
Also...
Conversation.all.count returns 1!
and:
Conversation.all == self.mailbox.conversations returns true
and
Conversation.all.count == self.mailbox.conversations.count returns false
How can that be if the arrays are equal? I don't know what's going on here, blown hours on this now. Think it's a bug?!
EDIT 3
From the source of the Mailboxer gem...
def conversations(options = {})
conv = Conversation.participant(#messageable)
if options[:mailbox_type].present?
case options[:mailbox_type]
when 'inbox'
conv = Conversation.inbox(#messageable)
when 'sentbox'
conv = Conversation.sentbox(#messageable)
when 'trash'
conv = Conversation.trash(#messageable)
when 'not_trash'
conv = Conversation.not_trash(#messageable)
end
end
if (options.has_key?(:read) && options[:read]==false) || (options.has_key?(:unread) && options[:unread]==true)
conv = conv.unread(#messageable)
end
conv
end
The reply_to_convesation code is available here -> http://rubydoc.info/gems/mailboxer/frames.
Just can't see what I'm doing wrong! Might rework my tests to get around this. Or ditch the gem and write my own.
see this Rails 3: Difference between Relation.count and Relation.all.count
In short Rails ignores the select columns (if more than one) when you apply count to the query. This is because
SQL's COUNT allows only one or less columns as parameters.
From Mailbox code
scope :participant, lambda {|participant|
select('DISTINCT conversations.*').
where('notifications.type'=> Message.name).
order("conversations.updated_at DESC").
joins(:receipts).merge(Receipt.recipient(participant))
}
self.mailbox.conversations.count ignores the select('DISTINCT conversations.*') and counts the join table with receipts, essentially counting number of receipts with duplicate conversations in it.
On the other hand, self.mailbox.conversations.all.count first gets the records applying the select, which gets unique conversations and then counts it.
self.mailbox.conversations.all == self.mailbox.conversations since both of them query the db with the select.
To solve your problem you can use sending_user.mailbox.conversations.all.count or sending_user.mailbox.conversations.group('conversations.id').length
I have tended to use the size method in my code. As per the ActiveRecord code, size will use a cached count if available and also returns the correct number when models have been created through relations and have not yet been saved.
# File activerecord/lib/active_record/relation.rb, line 228
def size
loaded? ? #records.length : count
end
There is a blog on this here.
In Ruby, #length and #size are synonyms and both do the same thing: they tell you how many elements are in an array or hash. Technically #length is the method and #size is an alias to it.
In ActiveRecord, there are several ways to find out how many records are in an association, and there are some subtle differences in how they work.
post.comments.count - Determine the number of elements with an SQL COUNT query. You can also specify conditions to count only a subset of the associated elements (e.g. :conditions => {:author_name => "josh"}). If you set up a counter cache on the association, #count will return that cached value instead of executing a new query.
post.comments.length - This always loads the contents of the association into memory, then returns the number of elements loaded. Note that this won't force an update if the association had been previously loaded and then new comments were created through another way (e.g. Comment.create(...) instead of post.comments.create(...)).
post.comments.size - This works as a combination of the two previous options. If the collection has already been loaded, it will return its length just like calling #length. If it hasn't been loaded yet, it's like calling #count.
It is also worth mentioning to be careful if you are not creating models through associations, as the related model will not necessarily have those instances in its association proxy/collection.
# do this
mailbox.conversations.build(attrs)
# or this
mailbox.conversations << Conversation.new(attrs)
# or this
mailbox.conversations.create(attrs)
# or this
mailbox.conversations.create!(attrs)
# NOT this
Conversation.new(mailbox_id: some_id, ....)
I don't know if this explains what's going on, but the ActiveRecord count method queries the database for the number of records stored. The length of the Relation could be different, as discussed in http://archive.railsforum.com/viewtopic.php?id=6255, although in that example, the number of records in the database was less than the number of items in the Rails data structure.
Try
self.mailbox.conversations.reload; self.mailbox.conversations.count
or perhaps
self.mailbox.reload; self.mailbox.conversations.count
or, if neither of those work, just try reloading as many of the objects as possible to see if you can get it to work (self, mailbox, conversations, etc.).
My guess is that something is messed up between memory and the DB. This is definitely a really weird error though, might wanna put in an issue on Rails to see why this would be the case.
The result of mailbox.conversations is cached after the first call. To reload it write mailbox.conversations(true)
I have a Model PromoCode which has a .generate! method, that calls .generate which generates a String using SecureRandom.hex(5) and saves it to the database:
class PromoCode < ActiveRecord::Base
class << self
def generate
SecureRandom.hex 5
end
def generate!
return create! code: generate
end
end
end
Now I want to write a spec that test the uniqueness of the generated string. The .generate method should be called as long as a non existent PromoCode has been generated.
I'm not sure how to do this since I can't really stub out the .generate method to return fixed values (because then it would be stuck in an infinite loop).
This is the passing spec for the model so far:
describe PromoCode do
describe ".generate" do
it "should return a string with a length of 10" do
code = PromoCode.generate
code.should be_a String
code.length.should eql 10
end
end
describe ".generate!" do
it "generates and returns a promocode" do
expect {
#promo = PromoCode.generate!
}.to change { PromoCode.count }.from(0).to(1)
#promo.code.should_not be_nil
#promo.code.length.should eql 10
end
it "generates a uniq promocode" do
end
end
end
Any directions appreciated.
Rspec's and_return method allows you to specify multiple return values that will be cycled through
For example you could write
PromoCode.stub(:generate).and_return('badcode1', 'badcode2', 'goodcode')
Which will cause the first call to generate to return 'badcode1', the second 'badcode2' etc... You can then check that the returned promocode was created with the correct code.
If you want to be race condition proof you'll want a database uniqueness constraint, so your code might actually want to be
def generate!
create!(...)
rescue ActiveRecord::RecordNotUnique
retry
end
In your spec you would stub the create! method to raise the first time but return a value the second time
And what about something like: create a PromoCode, save the result, and try to create a new PromoCode with the code of the previous PromoCode object:
it "should reject duplicate promocode" do
#promo = PromoCode.generate!
duplicate_promo = PromoCode.new(:code => #promo.code)
duplicate_promo.should_not be_valid
end
Also, this is model level, I am assuming you have a key in the database that will save you from race conditions...
If you saves the promocode in database you would have added validations there in the model for uniq promocode. So you can test the same in rspec too.
Like this,
it { should validate_uniqueness_of(:promocode) }
This answer is based on your comment:
I need to make sure that generate! generates a code - no matter what,
until a unique code has been generated.
I feel like you might have a hard time testing this correctly. Unit testing "no matter what" situations with indefinite loops can be a bit of a tricky subject.
I'm not sure how to do this since I can't really stub out the .generate method to return fixed values (because then it would be stuck in an infinite loop).
One possibility to consider might be if instead of doing either one or the other, you tried both? (That is, find a way make it return a fixed number under certain circumstances, and eventually trigger the actual random number. An instance variable counter might help; set it to a random number, count it down, when it's greater than zero return the fixed number, or something along those lines). This still doesn't feel like a perfect test, though, or even a very good one for that matter.
It might be worth looking more into means of generating similar strings with high probability of them being unique, and having some mathematical proof of it being that way. I'm not saying this is the most practical idea either, but if you really need to prove (as you're trying to do with tests), it might be the more probably solution.