Use NotesFinder in IssuableActions module

Remove project from NotesFinder constructor

Add project parameter to specs

Also look for methods in private scope

Fix specs to match new NotesFinder constructor

15 files changed, 316 insertions, 78 deletions

diff --git a/app/controllers/concerns/issuable_actions.rb b/app/controllers/concerns/issuable_actions.rb
index 6fa2f75be33..8a27b7f1c5f 100644
--- a/app/controllers/concerns/issuable_actions.rb
+++ b/app/controllers/concerns/issuable_actions.rb
@@ -98,13 +98,12 @@ module IssuableActions
     render json: { notice: "#{quantity} #{resource_name.pluralize(quantity)} updated" }
   end
 
-  # rubocop: disable CodeReuse/ActiveRecord
+  # rubocop:disable CodeReuse/ActiveRecord
   def discussions
-    notes = issuable.discussion_notes
-      .inc_relations_for_view
-      .with_notes_filter(notes_filter)
-      .includes(:noteable)
-      .fresh
+    notes = NotesFinder.new(current_user, finder_params_for_issuable).execute
+                .inc_relations_for_view
+                .includes(:noteable)
+                .fresh
 
     if notes_filter != UserPreference::NOTES_FILTERS[:only_comments]
       notes = ResourceEvents::MergeIntoNotesService.new(issuable, current_user).execute(notes)
@@ -117,7 +116,7 @@ module IssuableActions
 
     render json: discussion_serializer.represent(discussions, context: self)
   end
-  # rubocop: enable CodeReuse/ActiveRecord
+  # rubocop:enable CodeReuse/ActiveRecord
 
   private
 
@@ -222,4 +221,13 @@ module IssuableActions
   def parent
     @project || @group # rubocop:disable Gitlab/ModuleWithInstanceVariables
   end
+
+  # rubocop:disable Gitlab/ModuleWithInstanceVariables
+  def finder_params_for_issuable
+    {
+        target: @issuable,
+        notes_filter: notes_filter
+    }.tap { |hash| hash[:project] = project if respond_to?(:project, true) }
+  end
+  # rubocop:enable Gitlab/ModuleWithInstanceVariables
 end
diff --git a/app/controllers/concerns/notes_actions.rb b/app/controllers/concerns/notes_actions.rb
index 0098c4cdf4c..d2a961efff7 100644
--- a/app/controllers/concerns/notes_actions.rb
+++ b/app/controllers/concerns/notes_actions.rb
@@ -243,7 +243,7 @@ module NotesActions
   end
 
   def notes_finder
-    @notes_finder ||= NotesFinder.new(project, current_user, finder_params)
+    @notes_finder ||= NotesFinder.new(current_user, finder_params)
   end
 
   def note_serializer
diff --git a/app/controllers/projects/notes_controller.rb b/app/controllers/projects/notes_controller.rb
index 3152a38fd8e..65d9b074eee 100644
--- a/app/controllers/projects/notes_controller.rb
+++ b/app/controllers/projects/notes_controller.rb
@@ -68,7 +68,7 @@ class Projects::NotesController < Projects::ApplicationController
   alias_method :awardable, :note
 
   def finder_params
-    params.merge(last_fetched_at: last_fetched_at, notes_filter: notes_filter)
+    params.merge(project: project, last_fetched_at: last_fetched_at, notes_filter: notes_filter)
   end
 
   def authorize_admin_note!
diff --git a/app/controllers/snippets/notes_controller.rb b/app/controllers/snippets/notes_controller.rb
index 612897f27e6..1f016493c1f 100644
--- a/app/controllers/snippets/notes_controller.rb
+++ b/app/controllers/snippets/notes_controller.rb
@@ -27,7 +27,9 @@ class Snippets::NotesController < ApplicationController
   alias_method :noteable, :snippet
 
   def finder_params
-    params.merge(last_fetched_at: last_fetched_at, target_id: snippet.id, target_type: 'personal_snippet')
+    params.merge(last_fetched_at: last_fetched_at, target_id: snippet.id, target_type: 'personal_snippet').tap do |hash|
+      hash[:project] = project if respond_to?(:project)
+    end
   end
 
   def authorize_read_snippet!
diff --git a/app/finders/notes_finder.rb b/app/finders/notes_finder.rb
index 8f610d7dddb..f7d9100bb78 100644
--- a/app/finders/notes_finder.rb
+++ b/app/finders/notes_finder.rb
@@ -3,6 +3,8 @@
 class NotesFinder
   FETCH_OVERLAP = 5.seconds
 
+  attr_reader :target_type
+
   # Used to filter Notes
   # When used with target_type and target_id this returns notes specifically for the controller
   #
@@ -10,15 +12,17 @@ class NotesFinder
   #   current_user - which user check authorizations with
   #   project - which project to look for notes on
   #   params:
+  #     target: noteable
   #     target_type: string
   #     target_id: integer
   #     last_fetched_at: time
   #     search: string
   #
-  def initialize(project, current_user, params = {})
-    @project = project
+  def initialize(current_user, params = {})
+    @project = params[:project]
     @current_user = current_user
-    @params = params
+    @params = params.dup
+    @target_type = @params[:target_type]
   end
 
   def execute
@@ -32,7 +36,27 @@ class NotesFinder
   def target
     return @target if defined?(@target)
 
-    target_type = @params[:target_type]
+    if target_given?
+      use_explicit_target
+    else
+      find_target_by_type_and_ids
+    end
+  end
+
+  private
+
+  def target_given?
+    @params.key?(:target)
+  end
+
+  def use_explicit_target
+    @target = @params[:target]
+    @target_type = @target.class.name.underscore
+
+    @target
+  end
+
+  def find_target_by_type_and_ids
     target_id   = @params[:target_id]
     target_iid  = @params[:target_iid]
 
@@ -45,13 +69,11 @@ class NotesFinder
           @project.commit(target_id)
         end
       else
-        noteables_for_type_by_id(target_type, target_id, target_iid)
+        noteable_for_type_by_id(target_type, target_id, target_iid)
       end
   end
 
-  private
-
-  def noteables_for_type_by_id(type, id, iid)
+  def noteable_for_type_by_id(type, id, iid)
     query = if id
               { id: id }
             else
@@ -77,10 +99,6 @@ class NotesFinder
     search(notes)
   end
 
-  def target_type
-    @params[:target_type]
-  end
-
   # rubocop: disable CodeReuse/ActiveRecord
   def notes_of_any_type
     types = %w(commit issue merge_request snippet)
diff --git a/lib/api/helpers/notes_helpers.rb b/lib/api/helpers/notes_helpers.rb
index b03ac7deb71..7124ac0c5c3 100644
--- a/lib/api/helpers/notes_helpers.rb
+++ b/lib/api/helpers/notes_helpers.rb
@@ -76,7 +76,7 @@ module API
       def find_noteable(parent_type, parent_id, noteable_type, noteable_id)
         params = params_by_noteable_type_and_id(noteable_type, noteable_id)
 
-        noteable = NotesFinder.new(user_project, current_user, params).target
+        noteable = NotesFinder.new(current_user, params.merge(project: user_project)).target
         noteable = nil unless can?(current_user, noteable_read_ability_name(noteable), noteable)
         noteable || not_found!(noteable_type)
       end
diff --git a/lib/gitlab/project_search_results.rb b/lib/gitlab/project_search_results.rb
index 0f3b97e2317..827f4f77f36 100644
--- a/lib/gitlab/project_search_results.rb
+++ b/lib/gitlab/project_search_results.rb
@@ -108,7 +108,7 @@ module Gitlab
 
     # rubocop: disable CodeReuse/ActiveRecord
     def notes_finder(type)
-      NotesFinder.new(project, @current_user, search: query, target_type: type).execute.user.order('updated_at DESC')
+      NotesFinder.new(@current_user, search: query, target_type: type, project: project).execute.user.order('updated_at DESC')
     end
     # rubocop: enable CodeReuse/ActiveRecord
 
diff --git a/spec/controllers/concerns/issuable_actions_spec.rb b/spec/controllers/concerns/issuable_actions_spec.rb
new file mode 100644
index 00000000000..7b0b4497f3f
--- /dev/null
+++ b/spec/controllers/concerns/issuable_actions_spec.rb
@@ -0,0 +1,69 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe IssuableActions do
+  let(:project) { double('project') }
+  let(:user) { double('user') }
+  let(:issuable) { double('issuable') }
+  let(:finder_params_for_issuable) { {} }
+  let(:notes_result) { double('notes_result') }
+  let(:discussion_serializer) { double('discussion_serializer') }
+
+  let(:controller) do
+    klass = Class.new do
+      attr_reader :current_user, :project, :issuable
+
+      def self.before_action(action, params = nil)
+      end
+
+      include IssuableActions
+
+      def initialize(issuable, project, user, finder_params)
+        @issuable = issuable
+        @project = project
+        @current_user = user
+        @finder_params = finder_params
+      end
+
+      def finder_params_for_issuable
+        @finder_params
+      end
+
+      def params
+        {
+          notes_filter: 1
+        }
+      end
+
+      def prepare_notes_for_rendering(notes)
+        []
+      end
+
+      def render(options)
+      end
+    end
+
+    klass.new(issuable, project, user, finder_params_for_issuable)
+  end
+
+  describe '#discussions' do
+    before do
+      allow(user).to receive(:set_notes_filter)
+      allow(user).to receive(:user_preference)
+      allow(discussion_serializer).to receive(:represent)
+    end
+
+    it 'instantiates and calls NotesFinder as expected' do
+      expect(Discussion).to receive(:build_collection).and_return([])
+      expect(DiscussionSerializer).to receive(:new).and_return(discussion_serializer)
+      expect(NotesFinder).to receive(:new).with(user, finder_params_for_issuable).and_call_original
+
+      expect_any_instance_of(NotesFinder).to receive(:execute).and_return(notes_result)
+
+      expect(notes_result).to receive_messages(inc_relations_for_view: notes_result, includes: notes_result, fresh: notes_result)
+
+      controller.discussions
+    end
+  end
+end
diff --git a/spec/controllers/projects/issues_controller_spec.rb b/spec/controllers/projects/issues_controller_spec.rb
index 32d14dce936..0f885d776e1 100644
--- a/spec/controllers/projects/issues_controller_spec.rb
+++ b/spec/controllers/projects/issues_controller_spec.rb
@@ -1260,6 +1260,28 @@ describe Projects::IssuesController do
         sign_in(user)
       end
 
+      context do
+        it_behaves_like 'discussions provider' do
+          let!(:author) { create(:user) }
+          let!(:project) { create(:project) }
+
+          let!(:issue) { create(:issue, project: project, author: user) }
+
+          let!(:note_on_issue1) { create(:discussion_note_on_issue, noteable: issue, project: issue.project, author: create(:user)) }
+          let!(:note_on_issue2) { create(:discussion_note_on_issue, noteable: issue, project: issue.project, author: create(:user)) }
+
+          let(:requested_iid) { issue.iid }
+          let(:expected_discussion_count) { 3 }
+          let(:expected_discussion_ids) do
+            [
+              issue.notes.first.discussion_id,
+              note_on_issue1.discussion_id,
+              note_on_issue2.discussion_id
+            ]
+          end
+        end
+      end
+
       it 'returns discussion json' do
         get :discussions, params: { namespace_id: project.namespace, project_id: project, id: issue.iid }
 
diff --git a/spec/controllers/projects/merge_requests_controller_spec.rb b/spec/controllers/projects/merge_requests_controller_spec.rb
index 57a432de3f5..b1dc6a65dd4 100644
--- a/spec/controllers/projects/merge_requests_controller_spec.rb
+++ b/spec/controllers/projects/merge_requests_controller_spec.rb
@@ -1210,6 +1210,22 @@ describe Projects::MergeRequestsController do
         end
       end
     end
+
+    context do
+      it_behaves_like 'discussions provider' do
+        let!(:author) { create(:user) }
+        let!(:project) { create(:project) }
+
+        let!(:merge_request) { create(:merge_request, source_project: project) }
+
+        let!(:mr_note1) { create(:discussion_note_on_merge_request, noteable: merge_request, project: project) }
+        let!(:mr_note2) { create(:discussion_note_on_merge_request, noteable: merge_request, project: project) }
+
+        let(:requested_iid) { merge_request.iid }
+        let(:expected_discussion_count) { 2 }
+        let(:expected_discussion_ids) { [mr_note1.discussion_id, mr_note2.discussion_id] }
+      end
+    end
   end
 
   describe 'GET edit' do
diff --git a/spec/controllers/projects/notes_controller_spec.rb b/spec/controllers/projects/notes_controller_spec.rb
index 98aea9056dc..9ab565dc2e8 100644
--- a/spec/controllers/projects/notes_controller_spec.rb
+++ b/spec/controllers/projects/notes_controller_spec.rb
@@ -43,7 +43,7 @@ describe Projects::NotesController do
       request.headers['X-Last-Fetched-At'] = last_fetched_at
 
       expect(NotesFinder).to receive(:new)
-        .with(anything, anything, hash_including(last_fetched_at: last_fetched_at))
+        .with(anything, hash_including(last_fetched_at: last_fetched_at))
         .and_call_original
 
       get :index, params: request_params
diff --git a/spec/finders/notes_finder_spec.rb b/spec/finders/notes_finder_spec.rb
index 87bde4ca2f6..88906adfeeb 100644
--- a/spec/finders/notes_finder_spec.rb
+++ b/spec/finders/notes_finder_spec.rb
@@ -14,7 +14,7 @@ describe NotesFinder do
       let!(:system_note) { create(:note_on_issue, project: project, system: true) }
 
       it 'returns only user notes when using only_comments filter' do
-        finder = described_class.new(project, user, notes_filter: UserPreference::NOTES_FILTERS[:only_comments])
+        finder = described_class.new(user, project: project, notes_filter: UserPreference::NOTES_FILTERS[:only_comments])
 
         notes = finder.execute
 
@@ -22,7 +22,7 @@ describe NotesFinder do
       end
 
       it 'returns only system notes when using only_activity filters' do
-        finder = described_class.new(project, user, notes_filter: UserPreference::NOTES_FILTERS[:only_activity])
+        finder = described_class.new(user, project: project, notes_filter: UserPreference::NOTES_FILTERS[:only_activity])
 
         notes = finder.execute
 
@@ -30,7 +30,7 @@ describe NotesFinder do
       end
 
       it 'gets all notes' do
-        finder = described_class.new(project, user, notes_filter: UserPreference::NOTES_FILTERS[:all_activity])
+        finder = described_class.new(user, project: project, notes_filter: UserPreference::NOTES_FILTERS[:all_activity])
 
         notes = finder.execute
 
@@ -41,7 +41,7 @@ describe NotesFinder do
     it 'finds notes on merge requests' do
       create(:note_on_merge_request, project: project)
 
-      notes = described_class.new(project, user).execute
+      notes = described_class.new(user, project: project).execute
 
       expect(notes.count).to eq(1)
     end
@@ -49,7 +49,7 @@ describe NotesFinder do
     it 'finds notes on snippets' do
       create(:note_on_project_snippet, project: project)
 
-      notes = described_class.new(project, user).execute
+      notes = described_class.new(user, project: project).execute
 
       expect(notes.count).to eq(1)
     end
@@ -59,13 +59,13 @@ describe NotesFinder do
       note = create(:note_on_commit, project: project)
       params = { target_type: 'commit', target_id: note.noteable.id }
 
-      notes = described_class.new(project, create(:user), params).execute
+      notes = described_class.new(create(:user), params).execute
 
       expect(notes.count).to eq(0)
     end
 
     it 'succeeds when no notes found' do
-      notes = described_class.new(project, create(:user)).execute
+      notes = described_class.new(create(:user), project: project).execute
 
       expect(notes.count).to eq(0)
     end
@@ -82,7 +82,7 @@ describe NotesFinder do
       it 'publicly excludes notes on merge requests' do
         create(:note_on_merge_request, project: project)
 
-        notes = described_class.new(project, create(:user)).execute
+        notes = described_class.new(create(:user), project: project).execute
 
         expect(notes.count).to eq(0)
       end
@@ -90,7 +90,7 @@ describe NotesFinder do
       it 'publicly excludes notes on issues' do
         create(:note_on_issue, project: project)
 
-        notes = described_class.new(project, create(:user)).execute
+        notes = described_class.new(create(:user), project: project).execute
 
         expect(notes.count).to eq(0)
       end
@@ -98,7 +98,7 @@ describe NotesFinder do
       it 'publicly excludes notes on snippets' do
         create(:note_on_project_snippet, project: project)
 
-        notes = described_class.new(project, create(:user)).execute
+        notes = described_class.new(create(:user), project: project).execute
 
         expect(notes.count).to eq(0)
       end
@@ -110,7 +110,7 @@ describe NotesFinder do
       let!(:note2) { create :note_on_commit, project: project }
 
       it 'finds only notes for the selected type' do
-        notes = described_class.new(project, user, target_type: 'issue').execute
+        notes = described_class.new(user, project: project, target_type: 'issue').execute
 
         expect(notes).to eq([note1])
       end
@@ -118,56 +118,51 @@ describe NotesFinder do
 
     context 'for target' do
       let(:project) { create(:project, :repository) }
-      let(:note1) { create :note_on_commit, project: project }
-      let(:note2) { create :note_on_commit, project: project }
+      let!(:note1) { create :note_on_commit, project: project }
+      let!(:note2) { create :note_on_commit, project: project }
       let(:commit) { note1.noteable }
-      let(:params) { { target_id: commit.id, target_type: 'commit', last_fetched_at: 1.hour.ago.to_i } }
-
-      before do
-        note1
-        note2
-      end
+      let(:params) { { project: project, target_id: commit.id, target_type: 'commit', last_fetched_at: 1.hour.ago.to_i } }
 
       it 'finds all notes' do
-        notes = described_class.new(project, user, params).execute
+        notes = described_class.new(user, params).execute
         expect(notes.size).to eq(2)
       end
 
       it 'finds notes on merge requests' do
         note = create(:note_on_merge_request, project: project)
-        params = { target_type: 'merge_request', target_id: note.noteable.id }
+        params = { project: project, target_type: 'merge_request', target_id: note.noteable.id }
 
-        notes = described_class.new(project, user, params).execute
+        notes = described_class.new(user, params).execute
 
         expect(notes).to include(note)
       end
 
       it 'finds notes on snippets' do
         note = create(:note_on_project_snippet, project: project)
-        params = { target_type: 'snippet', target_id: note.noteable.id }
+        params = { project: project, target_type: 'snippet', target_id: note.noteable.id }
 
-        notes = described_class.new(project, user, params).execute
+        notes = described_class.new(user, params).execute
 
         expect(notes.count).to eq(1)
       end
 
       it 'finds notes on personal snippets' do
         note = create(:note_on_personal_snippet)
-        params = { target_type: 'personal_snippet', target_id: note.noteable_id }
+        params = { project: project, target_type: 'personal_snippet', target_id: note.noteable_id }
 
-        notes = described_class.new(project, user, params).execute
+        notes = described_class.new(user, params).execute
 
         expect(notes.count).to eq(1)
       end
 
       it 'raises an exception for an invalid target_type' do
         params[:target_type] = 'invalid'
-        expect { described_class.new(project, user, params).execute }.to raise_error("invalid target_type '#{params[:target_type]}'")
+        expect { described_class.new(user, params).execute }.to raise_error("invalid target_type '#{params[:target_type]}'")
       end
 
       it 'filters out old notes' do
         note2.update_attribute(:updated_at, 2.hours.ago)
-        notes = described_class.new(project, user, params).execute
+        notes = described_class.new(user, params).execute
         expect(notes).to eq([note1])
       end
 
@@ -175,25 +170,47 @@ describe NotesFinder do
         let(:confidential_issue) { create(:issue, :confidential, project: project, author: user) }
         let!(:confidential_note) { create(:note, noteable: confidential_issue, project: confidential_issue.project) }
 
-        let(:params) { { target_id: confidential_issue.id, target_type: 'issue', last_fetched_at: 1.hour.ago.to_i } }
+        let(:params) { { project: confidential_issue.project, target_id: confidential_issue.id, target_type: 'issue', last_fetched_at: 1.hour.ago.to_i } }
 
         it 'returns notes if user can see the issue' do
-          expect(described_class.new(project, user, params).execute).to eq([confidential_note])
+          expect(described_class.new(user, params).execute).to eq([confidential_note])
         end
 
         it 'raises an error if user can not see the issue' do
           user = create(:user)
-          expect { described_class.new(project, user, params).execute }.to raise_error(ActiveRecord::RecordNotFound)
+          expect { described_class.new(user, params).execute }.to raise_error(ActiveRecord::RecordNotFound)
         end
 
         it 'raises an error for project members with guest role' do
           user = create(:user)
           project.add_guest(user)
 
-          expect { described_class.new(project, user, params).execute }.to raise_error(ActiveRecord::RecordNotFound)
+          expect { described_class.new(user, params).execute }.to raise_error(ActiveRecord::RecordNotFound)
         end
       end
     end
+
+    context 'for explicit target' do
+      let(:project) { create(:project, :repository) }
+      let!(:note1) { create :note_on_commit, project: project, created_at: 1.day.ago, updated_at: 2.hours.ago }
+      let!(:note2) { create :note_on_commit, project: project }
+      let(:commit) { note1.noteable }
+      let(:params) { { project: project, target: commit } }
+
+      it 'returns the expected notes' do
+        expect(described_class.new(user, params).execute).to eq([note1, note2])
+      end
+
+      it 'returns the expected notes when last_fetched_at is given' do
+        params = { project: project, target: commit, last_fetched_at: 1.hour.ago.to_i }
+        expect(described_class.new(user, params).execute).to eq([note2])
+      end
+
+      it 'fails when nil is provided' do
+        params = { project: project, target: nil }
+        expect { described_class.new(user, params).execute }.to raise_error(RuntimeError)
+      end
+    end
   end
 
   describe '.search' do
@@ -201,17 +218,17 @@ describe NotesFinder do
     let(:note) { create(:note_on_issue, note: 'WoW', project: project) }
 
     it 'returns notes with matching content' do
-      expect(described_class.new(note.project, nil, search: note.note).execute).to eq([note])
+      expect(described_class.new(nil, project: note.project, search: note.note).execute).to eq([note])
     end
 
     it 'returns notes with matching content regardless of the casing' do
-      expect(described_class.new(note.project, nil, search: 'WOW').execute).to eq([note])
+      expect(described_class.new(nil, project: note.project, search: 'WOW').execute).to eq([note])
     end
 
     it 'returns commit notes user can access' do
       note = create(:note_on_commit, project: project)
 
-      expect(described_class.new(note.project, create(:user), search: note.note).execute).to eq([note])
+      expect(described_class.new(create(:user), project: note.project, search: note.note).execute).to eq([note])
     end
 
     context "confidential issues" do
@@ -220,27 +237,27 @@ describe NotesFinder do
       let(:confidential_note) { create(:note, note: "Random", noteable: confidential_issue, project: confidential_issue.project) }
 
       it "returns notes with matching content if user can see the issue" do
-        expect(described_class.new(confidential_note.project, user, search: confidential_note.note).execute).to eq([confidential_note])
+        expect(described_class.new(user, project: confidential_note.project, search: confidential_note.note).execute).to eq([confidential_note])
       end
 
       it "does not return notes with matching content if user can not see the issue" do
         user = create(:user)
-        expect(described_class.new(confidential_note.project, user, search: confidential_note.note).execute).to be_empty
+        expect(described_class.new(user, project: confidential_note.project, search: confidential_note.note).execute).to be_empty
       end
 
       it "does not return notes with matching content for project members with guest role" do
         user = create(:user)
         project.add_guest(user)
-        expect(described_class.new(confidential_note.project, user, search: confidential_note.note).execute).to be_empty
+        expect(described_class.new(user, project: confidential_note.project, search: confidential_note.note).execute).to be_empty
       end
 
       it "does not return notes with matching content for unauthenticated users" do
-        expect(described_class.new(confidential_note.project, nil, search: confidential_note.note).execute).to be_empty
+        expect(described_class.new(nil, project: confidential_note.project, search: confidential_note.note).execute).to be_empty
       end
     end
 
     context 'inlines SQL filters on subqueries for performance' do
-      let(:sql) { described_class.new(note.project, nil, search: note.note).execute.to_sql }
+      let(:sql) { described_class.new(nil, project: note.project, search: note.note).execute.to_sql }
       let(:number_of_noteable_types) { 4 }
 
       specify 'project_id check' do
@@ -254,11 +271,11 @@ describe NotesFinder do
   end
 
   describe '#target' do
-    subject { described_class.new(project, user, params) }
+    subject { described_class.new(user, params) }
 
     context 'for a issue target' do
       let(:issue) { create(:issue, project: project) }
-      let(:params) { { target_type: 'issue', target_id: issue.id } }
+      let(:params) { { project: project, target_type: 'issue', target_id: issue.id } }
 
       it 'returns the issue' do
         expect(subject.target).to eq(issue)
@@ -267,7 +284,7 @@ describe NotesFinder do
 
     context 'for a merge request target' do
       let(:merge_request) { create(:merge_request, source_project: project) }
-      let(:params) { { target_type: 'merge_request', target_id: merge_request.id } }
+      let(:params) { { project: project, target_type: 'merge_request', target_id: merge_request.id } }
 
       it 'returns the merge_request' do
         expect(subject.target).to eq(merge_request)
@@ -276,7 +293,7 @@ describe NotesFinder do
 
     context 'for a snippet target' do
       let(:snippet) { create(:project_snippet, project: project) }
-      let(:params) { { target_type: 'snippet', target_id: snippet.id } }
+      let(:params) { { project: project, target_type: 'snippet', target_id: snippet.id } }
 
       it 'returns the snippet' do
         expect(subject.target).to eq(snippet)
@@ -286,7 +303,7 @@ describe NotesFinder do
     context 'for a commit target' do
       let(:project) { create(:project, :repository) }
       let(:commit) { project.commit }
-      let(:params) { { target_type: 'commit', target_id: commit.id } }
+      let(:params) { { project: project, target_type: 'commit', target_id: commit.id } }
 
       it 'returns the commit' do
         expect(subject.target).to eq(commit)
@@ -298,24 +315,24 @@ describe NotesFinder do
       let(:merge_request) { create(:merge_request, source_project: project, target_project: project) }
 
       it 'finds issues by iid' do
-        iid_params = { target_type: 'issue', target_iid: issue.iid }
-        expect(described_class.new(project, user, iid_params).target).to eq(issue)
+        iid_params = { project: project, target_type: 'issue', target_iid: issue.iid }
+        expect(described_class.new(user, iid_params).target).to eq(issue)
       end
 
       it 'finds merge requests by iid' do
-        iid_params = { target_type: 'merge_request', target_iid: merge_request.iid }
-        expect(described_class.new(project, user, iid_params).target).to eq(merge_request)
+        iid_params = { project: project, target_type: 'merge_request', target_iid: merge_request.iid }
+        expect(described_class.new(user, iid_params).target).to eq(merge_request)
       end
 
       it 'returns nil if both target_id and target_iid are not given' do
-        params_without_any_id = { target_type: 'issue' }
-        expect(described_class.new(project, user, params_without_any_id).target).to be_nil
+        params_without_any_id = { project: project, target_type: 'issue' }
+        expect(described_class.new(user, params_without_any_id).target).to be_nil
       end
 
       it 'prioritizes target_id over target_iid' do
         issue2 = create(:issue, project: project)
-        iid_params = { target_type: 'issue', target_id: issue2.id, target_iid: issue.iid }
-        expect(described_class.new(project, user, iid_params).target).to eq(issue2)
+        iid_params = { project: project, target_type: 'issue', target_id: issue2.id, target_iid: issue.iid }
+        expect(described_class.new(user, iid_params).target).to eq(issue2)
       end
     end
   end
diff --git a/spec/fixtures/api/schemas/entities/discussion.json b/spec/fixtures/api/schemas/entities/discussion.json
new file mode 100644
index 00000000000..bcc1db79e83
--- /dev/null
+++ b/spec/fixtures/api/schemas/entities/discussion.json
@@ -0,0 +1,67 @@
+{
+  "type": "object",
+  "required" : [
+    "id",
+    "notes",
+    "individual_note"
+  ],
+  "properties" : {
+    "id": { "type": "string" },
+    "individual_note": { "type": "boolean" },
+    "notes": {
+      "type": "array",
+      "items": {
+        "type": "object",
+        "properties" : {
+          "id": { "type": "string" },
+          "type": { "type": ["string", "null"] },
+          "body": { "type": "string" },
+          "attachment": { "type": ["string", "null"]},
+          "award_emoji": { "type": "array" },
+          "author": {
+            "type": "object",
+            "properties": {
+              "name": { "type": "string" },
+              "username": { "type": "string" },
+              "id": { "type": "integer" },
+              "state": { "type": "string" },
+              "avatar_url": { "type": "uri" },
+              "web_url": { "type": "uri" },
+              "status_tooltip_html": { "type": ["string", "null"] },
+              "path": { "type": "string" }
+            },
+            "additionalProperties": false
+          },
+          "created_at": { "type": "date" },
+          "updated_at": { "type": "date" },
+          "system": { "type": "boolean" },
+          "noteable_id": { "type": "integer" },
+          "noteable_iid": { "type": "integer" },
+          "noteable_type": { "type": "string" },
+          "resolved": { "type": "boolean" },
+          "resolvable": { "type": "boolean" },
+          "resolved_by": { "type": ["string", "null"] },
+          "note": { "type": "string" },
+          "note_html": { "type": "string"  },
+          "current_user": { "type": "object" },
+          "suggestions": { "type": "array" },
+          "discussion_id": { "type": "string" },
+          "emoji_awardable": { "type": "boolean" },
+          "report_abuse_path": { "type": "string" },
+          "noteable_note_url": { "type": "string" },
+          "resolve_path": { "type": "string" },
+          "resolve_with_issue_path": { "type": "string" },
+          "cached_markdown_version": { "type": "integer" },
+          "human_access": { "type": ["string", "null"] },
+          "toggle_award_path": { "type": "string" },
+          "path": { "type": "string" }
+        },
+        "required": [
+          "id", "attachment", "author", "created_at", "updated_at",
+          "system", "noteable_id", "noteable_type"
+        ],
+        "additionalProperties": false
+      }
+    }
+  }
+}
diff --git a/spec/fixtures/api/schemas/entities/discussions.json b/spec/fixtures/api/schemas/entities/discussions.json
new file mode 100644
index 00000000000..5a837429776
--- /dev/null
+++ b/spec/fixtures/api/schemas/entities/discussions.json
@@ -0,0 +1,4 @@
+{
+  "type": "array",
+  "items": { "$ref": "discussion.json" }
+}
diff --git a/spec/support/shared_examples/discussions_provider_shared_examples.rb b/spec/support/shared_examples/discussions_provider_shared_examples.rb
new file mode 100644
index 00000000000..77cf1ac3f51
--- /dev/null
+++ b/spec/support/shared_examples/discussions_provider_shared_examples.rb
@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+shared_examples 'discussions provider' do
+  it 'returns the expected discussions' do
+    get :discussions, params: { namespace_id: project.namespace, project_id: project, id: requested_iid }
+
+    expect(response).to have_gitlab_http_status(200)
+    expect(response).to match_response_schema('entities/discussions')
+
+    expect(json_response.size).to eq(expected_discussion_count)
+    expect(json_response.pluck('id')).to eq(expected_discussion_ids)
+  end
+end