How to test "initialize" method using RSpec - ruby

Question

github_asset.rb
# frozen_string_literal: true
require 'asset_ingester/helpers/project_details'
require 'active_model'
module AssetIngester
module Asset
class GithubAsset
include ActiveModel::Serializers::JSON
attr_reader :id, :name, :full_name, :description, :owner_name, :owner_url,
:owner_avatar_url, :url, :html_url, :artifact_id, :jiras, :asset_type
# Public: Initializes an instance of the GithubAsset class
#
# repo - A hash containing github repository details
# asset_type - A string representation of the asset type
def initialize(repo, asset_type)
#id = repo[:id]
#name = repo[:name]
#full_name = repo[:full_name]
#description = repo[:description]
#owner_name = repo.dig(:owner, :login)
#owner_url = repo.dig(:owner, :url)
#owner_avatar_url = repo.dig(:owner, :avatar_url)
#url = repo[:url]
#html_url = repo[:html_url]
#asset_type = asset_type
#artifact_id = repo[:artifact_id] if repo[:artifact_id] && !repo[:artifact_id].empty?
#jiras = repo[:jiras] if repo[:jiras] && !repo[:jiras].empty?
end
# Public: Defines the JSON serialization structure
#
# https://edgeguides.rubyonrails.org/active_model_basics.html#serialization
def attributes
{
'id' => #id,
'name' => #name,
'full_name' => #full_name,
'description' => #description,
'owner_name' => #owner_name,
'owner_url' => #owner_url,
'owner_avatar_url' => #owner_avatar_url,
'url' => #url,
'html_url' => #html_url,
'asset_type' => #asset_type,
'artifact_id' => #artifact_id,
'jiras' => #jiras
}.compact
end
end
end
end
github_asset_spec.rb
require 'asset_ingester/asset/github_asset'
RSpec.describe AssetIngester::Asset::GithubAsset, type: :api do
context "creating" do
let(:asset_type) {"node_package"}
let(:repo) do
[id: 131_690,
name: 'acm-care-management-js',
full_name: 'AcuteCaseManagementUI/acm-care-management-js',
owner_name: 'AcuteCaseManagementUI',
owner_url: 'https://github.cerner.com/api/v3/users/AcuteCaseManagementUI',
owner_avatar_url: 'https://avatars.github.cerner.com/u/4095?',
url: 'https://github.cerner.com/api/v3/repos/AcuteCaseManagementUI/acm-care-management-js',
html_url: 'https://github.cerner.com/AcuteCaseManagementUI/acm-care-management-js',
asset_type: 'node_package',
artifact_id: "",
jiras: [] ]
end
describe '::attributes' do
subject { AssetIngester::Asset::GithubAsset.attributes(repo, asset_type) }
it 'instantiates the class with 2 arguments' do
expect(subject).to be_an_instance_of(AssetIngester::Asset::GithubAsset)
end
it 'sets a to the first argument' do
expect(subject.repo).to eq(repo)
end
it 'sets b to the second argument' do
expect(subject.asset_type).to eq(asset_type)
end
end
end
end
This is how i tried testing the github_asset.rb file but however I'am receiving the following error while defining the subject
AssetIngester::Asset::GithubAsset creating ::attributes instantiates the class with 2 arguments
Failure/Error: subject { AssetIngester::Asset::GithubAsset.attributes(repo, asset_type) }
NoMethodError:
undefined method `attributes' for AssetIngester::Asset::GithubAsset:Class
Did you mean? attr_writer
I am green to RSpec testing and want to know how this can be done.

Answer 1

You get that NoMethodError because you are trying to call attributes as a class method:
subject { AssetIngester::Asset::GithubAsset.attributes(repo, asset_type) }
# ^^^^^^^^^^
although in your code, attributes is defined as an instance method.
But apart from that, you ask "how ruby initialize method can be tested" and apparently your test code is all about initialize and not about attributes, so let's start at the beginning:
describe '::attributes' do
# ...
end
You want to test initialize, so attributes should be initialize. And since initialize is an instance method (rather than a class method), :: should be #:
describe '#initialize' do
# ...
end
And your subject should be an instance of GithubAsset which is created via new1:
describe '#initialize' do
subject { AssetIngester::Asset::GithubAsset.new(repo, asset_type) }
# ...
end
With that in place, you can start writing your tests, e.g.:
describe '#initialize' do
subject { AssetIngester::Asset::GithubAsset.new(repo, asset_type) }
it 'sets the id attribute' do
expect(subject.id).to eq(131690)
end
end
1 In Ruby, you rarely invoke ::allocate and #initialize directly. So instead of:
obj = Array.allocate
obj.send(:initialize, 5) { |i| i ** 2 }
obj #=> [0, 1, 4, 9, 16]
you typically just call new and let it call allocate and initialize for you:
obj = Array.new(5) { |i| i ** 2 }
obj #=> [0, 1, 4, 9, 16]