Add models to represent "Collections" (#36977)

spec/fabricators/account_fabricator.rb

@@ -17,3 +17,7 @@ Fabricator(:account) do
   discoverable        true
   indexable           true
 end
+
+Fabricator(:remote_account, from: :account) do
+  domain 'example.com'
+end

spec/fabricators/collection_fabricator.rb

@@ -0,0 +1,10 @@
+# frozen_string_literal: true
+
+Fabricator(:collection) do
+  account      { Fabricate.build(:account) }
+  name         { sequence(:name) { |i| "Collection ##{i}" } }
+  description  'People to follow'
+  local        true
+  sensitive    false
+  discoverable true
+end

spec/fabricators/collection_item_fabricator.rb

@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+Fabricator(:collection_item) do
+  collection                { Fabricate.build(:collection) }
+  account                   { Fabricate.build(:account) }
+  position                  1
+  state                     :accepted
+end
+
+Fabricator(:unverified_remote_collection_item, from: :collection_item) do
+  account      nil
+  state        :pending
+  object_uri   { Fabricate.build(:remote_account).uri }
+  approval_uri { sequence(:uri) { |i| "https://example.com/authorizations/#{i}" } }
+end

spec/models/collection_item_spec.rb

@@ -0,0 +1,41 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe CollectionItem do
+  describe 'Validations' do
+    subject { Fabricate.build(:collection_item) }
+
+    it { is_expected.to define_enum_for(:state) }
+
+    it { is_expected.to validate_numericality_of(:position).only_integer.is_greater_than(0) }
+
+    context 'when account inclusion is accepted' do
+      subject { Fabricate.build(:collection_item, state: :accepted) }
+
+      it { is_expected.to validate_presence_of(:account) }
+    end
+
+    context 'when item is local and account is remote' do
+      subject { Fabricate.build(:collection_item, account: remote_account) }
+
+      let(:remote_account) { Fabricate.build(:remote_account) }
+
+      it { is_expected.to validate_presence_of(:activity_uri) }
+    end
+
+    context 'when item is not local' do
+      subject { Fabricate.build(:collection_item, collection: remote_collection) }
+
+      let(:remote_collection) { Fabricate.build(:collection, local: false) }
+
+      it { is_expected.to validate_absence_of(:approval_uri) }
+    end
+
+    context 'when account is not present' do
+      subject { Fabricate.build(:unverified_remote_collection_item) }
+
+      it { is_expected.to validate_presence_of(:object_uri) }
+    end
+  end
+end

spec/models/collection_spec.rb

@@ -0,0 +1,45 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe Collection do
+  describe 'Validations' do
+    subject { Fabricate.build :collection }
+
+    it { is_expected.to validate_presence_of(:name) }
+
+    it { is_expected.to validate_presence_of(:description) }
+
+    context 'when collection is remote' do
+      subject { Fabricate.build :collection, local: false }
+
+      it { is_expected.to validate_presence_of(:uri) }
+
+      it { is_expected.to validate_presence_of(:original_number_of_items) }
+    end
+
+    context 'when using a hashtag as category' do
+      subject { Fabricate.build(:collection, tag:) }
+
+      context 'when hashtag is usable' do
+        let(:tag) { Fabricate.build(:tag) }
+
+        it { is_expected.to be_valid }
+      end
+
+      context 'when hashtag is not usable' do
+        let(:tag) { Fabricate.build(:tag, usable: false) }
+
+        it { is_expected.to_not be_valid }
+      end
+    end
+
+    context 'when there are more items than allowed' do
+      subject { Fabricate.build(:collection, collection_items:) }
+
+      let(:collection_items) { Fabricate.build_times(described_class::MAX_ITEMS + 1, :collection_item, collection: nil) }
+
+      it { is_expected.to_not be_valid }
+    end
+  end
+end