rspec model testing; method doesn't work - ruby-on-rails

Question

The method itself works as expected, but when I try to test it in the model spec the create part fails. The find part works well. What did I miss?
conversation.rb
scope :between, -> (sender_id, recipient_id) do
where("(conversations.sender_id = ? AND conversations.recipient_id = ?) OR (conversations.sender_id = ? AND conversations.recipient_id = ?)", sender_id, recipient_id, recipient_id, sender_id)
end
def self.create_or_find_conversation(task_assigner_id, task_executor_id)
Conversation.between(task_assigner_id, task_executor_id).first_or_create do |conversation|
conversation.sender_id = task_assigner_id
conversation.recipient_id = task_executor_id
end
end
conversation_spec.rb
describe "class methods" do
let(:sender) { create(:user) }
let(:recipient) { create(:user) }
let(:other_recipient) { create(:user) }
let!(:conversation) { create(:conversation, sender: sender, recipient: recipient) }
context "create_of_find_conversation" do
#this one throws Failure/Error: expect{conv}.to change{Conversation.count}.by(1)
#expected result to have changed by 1, but was changed by 0
it "creates conversation" do
conv = Conversation.create_or_find_conversation(sender, other_recipient)
expect{conv}.to change{Conversation.count}.by(1)
end
#this one is working as expected
it "finds conversation" do
conv = Conversation.create_or_find_conversation(sender, recipient)
expect(conv).to eq(conversation)
end
end
end

Answer 1

I think these code:
it "creates conversation" do
conv = Conversation.create_or_find_conversation(sender, other_recipient)
expect{conv}.to change{Conversation.count}.by(1)
end
should be changed to:
it "creates conversation" do
expect{
Conversation.create_or_find_conversation(sender.id, other_recipient.id)
}.to change{Conversation.count}.by(1)
end
because it was't the value changed the count, but the process.

Answer 2

Regular variables in Ruby are not lazy loading - the right side of the assignment is processed when the variable is assigned.
def do_something(val)
puts "do_something called"
val
end
a = do_something(hello_world)
puts a
# do_something called
# hello world
You would either need to change expection so that the action is called inside the block passed to expect:
it "creates conversation" do
expect do
Conversation.create_or_find_conversation(sender, other_recipient)
end.to change{Conversation.count}.by(1)
end
Or use RSpec's let to create a lazy loading variable:
let(:conv) { Conversation.create_or_find_conversation(sender, other_recipient) }
it "creates conversation" do
expect { conv }.to change{Conversation.count}.by(1)
end
But that does not fix the underlying problem that you are modeling the domain wrong. In a conversation both the sides take turns speaking - so using a recipient_id and sender_id is just plain wrong. Rather its messages that have a sender and receiver.
You can change them to be called whatever you want but it is much simpler to use a proper many to many relation so that you don't need a complex AND OR query.
class User < ActiveRecord::Base
has_many :user_conversations
has_many :conversations, through: user_conversations
end
class Conversation < ActiveRecord::Base
has_many :user_conversations
has_many :users, through: user_conversations
end
# the m2m join model.
class UserCoversation < ActiveRecord::Base
belongs_to :user
belongs_to :conversation
end
You can then simply query:
Conversation.where(users: [a, b])