Address review comments

app/helpers/notes_helper.rb

@@ -51,7 +51,6 @@ module NotesHelper
     return unless current_user
 
     data = { discussion_id: discussion.id, line_type: line_type }
-    data[:line_code] = discussion.line_code if discussion.respond_to?(:line_code)
 
     button_tag 'Reply...', class: 'btn btn-text-field js-discussion-reply-button',
                            data: data, title: 'Add a reply'

app/mailers/emails/notes.rb

@@ -5,11 +5,7 @@ module Emails
 
       @commit = @note.noteable
       @target_url = namespace_project_commit_url(*note_target_url_options)
-
-      mail_answer_thread(@commit,
-                         from: sender(@note.author_id),
-                         to: recipient(recipient_id),
-                         subject: subject("#{@commit.title} (#{@commit.short_id})"))
+      mail_answer_thread(@commit, note_thread_options(recipient_id))
     end
 
     def note_issue_email(recipient_id, note_id)
@@ -54,16 +50,18 @@ module Emails
       {
         from: sender(@note.author_id),
         to: recipient(recipient_id),
-        subject: subject("#{@note.noteable.title} (#{@note.noteable.to_reference})")
+        subject: subject("#{@note.noteable.title} (#{@note.noteable.reference_link_text})")
       }
     end
 
     def setup_note_mail(note_id, recipient_id)
-      @note = Note.find(note_id)
+      # `note_id` is a `Note` when originating in `NotifyPreview`
+      @note = note_id.is_a?(Note) ? note_id : Note.find(note_id)
       @project = @note.project
-      return unless @project
 
-      @sent_notification = SentNotification.record_note(@note, recipient_id, reply_key)
+      if @project && @note.persisted?
+        @sent_notification = SentNotification.record_note(@note, recipient_id, reply_key)
+      end
     end
   end
 end

app/models/concerns/discussion_on_diff.rb

+# Contains functionality shared between `DiffDiscussion` and `LegacyDiffDiscussion`.
 module DiscussionOnDiff
   extend ActiveSupport::Concern
 

app/models/concerns/note_on_diff.rb

+# Contains functionality shared between `DiffNote` and `LegacyDiffNote`.
 module NoteOnDiff
   extend ActiveSupport::Concern
 

app/models/concerns/noteable.rb

@@ -12,6 +12,32 @@ module Noteable
   end
 
   def grouped_diff_discussions
+    # Doesn't use `discussion_notes`, because this may include commit diff notes
+    # besides MR diff notes, that we do no want to display on the MR Changes tab.
     notes.inc_relations_for_view.grouped_diff_discussions
   end
+
+  def resolvable_discussions
+    @resolvable_discussions ||= discussion_notes.resolvable.discussions(self)
+  end
+
+  def discussions_resolvable?
+    resolvable_discussions.any?(&:resolvable?)
+  end
+
+  def discussions_resolved?
+    discussions_resolvable? && resolvable_discussions.none?(&:to_be_resolved?)
+  end
+
+  def discussions_to_be_resolved?
+    discussions_resolvable? && !discussions_resolved?
+  end
+
+  def discussions_to_be_resolved
+    @discussions_to_be_resolved ||= resolvable_discussions.select(&:to_be_resolved?)
+  end
+
+  def discussions_can_be_resolved_by?(user)
+    discussions_to_be_resolved.all? { |discussion| discussion.can_resolve?(user) }
+  end
 end

app/models/concerns/resolvable_discussion.rb

@@ -2,6 +2,15 @@ module ResolvableDiscussion
   extend ActiveSupport::Concern
 
   included do
+    # A number of properties of this `Discussion`, like `first_note` and `resolvable?`, are memoized.
+    # When this discussion is resolved or unresolved, the values of these properties potentially change.
+    # To make sure all memoized values are reset when this happens, `update` resets all instance variables with names in
+    # `memoized_variables`. If you add a memoized method in `ResolvableDiscussion` or any `Discussion` subclass,
+    # please make sure the instance variable name is added to `memoized_values`, like below.
+    cattr_accessor :memoized_values, instance_accessor: false do
+      []
+    end
+
     memoized_values.push(
       :resolvable,
       :resolved,
@@ -78,4 +87,20 @@ module ResolvableDiscussion
 
     update { |notes| notes.unresolve! }
   end
+
+  private
+
+  def update
+    # Do not select `Note.resolvable`, so that system notes remain in the collection
+    notes_relation = Note.where(id: notes.map(&:id))
+
+    yield(notes_relation)
+
+    # Set the notes array to the updated notes
+    @notes = notes_relation.fresh.to_a
+
+    self.class.memoized_values.each do |var|
+      instance_variable_set(:"@#{var}", nil)
+    end
+  end
 end

app/models/concerns/resolvable_note.rb

@@ -8,7 +8,7 @@ module ResolvableNote
 
     validates :resolved_by, presence: true, if: :resolved?
 
-    # Keep this scope in sync with the logic in `#potentially_resolvable?` in `Discussion` subclasses that are resolvable.
+    # Keep this scope in sync with the logic in `#potentially_resolvable?` in subclasses of `Discussion` that are resolvable.
     # `RESOLVABLE_TYPES` should include names of all subclasses that are resolvable (where the method can return true), and
     # the scope should also match the criteria `ResolvableDiscussion#potentially_resolvable?` puts on resolvability.
     scope :potentially_resolvable, -> { where(type: RESOLVABLE_TYPES).where(noteable_type: 'MergeRequest') }

app/models/diff_discussion.rb

-# A discussion on merge request or commit diffs consisting of `DiffNote` notes
+# A discussion on merge request or commit diffs consisting of `DiffNote` notes.
 class DiffDiscussion < Discussion
   include DiscussionOnDiff
 

app/models/discussion.rb

+# A non-diff discussion on an issue, merge request, commit, or snippet, consisting of `DiscussionNote` notes.
 class Discussion
-  cattr_accessor :memoized_values, instance_accessor: false do
-    []
-  end
-
   include ResolvableDiscussion
 
   attr_reader :notes, :noteable
@@ -25,23 +22,34 @@ class Discussion
     notes.group_by { |n| n.discussion_id(noteable) }.values.map { |notes| build(notes, noteable) }
   end
 
+  # Returns an alphanumeric discussion ID based on `build_discussion_id`
   def self.discussion_id(note)
     Digest::SHA1.hexdigest(build_discussion_id(note).join("-"))
   end
 
-  # Optionally override the discussion ID at runtime depending on circumstances
-  def self.override_discussion_id(note)
-    nil
+  # Returns an array of discussion ID components
+  def self.build_discussion_id(note)
+    [*base_discussion_id(note), SecureRandom.hex]
   end
 
-  def self.build_discussion_id_base(note)
+  def self.base_discussion_id(note)
     noteable_id = note.noteable_id || note.commit_id
     [:discussion, note.noteable_type.try(:underscore), noteable_id]
   end
 
-  # Returns an array of discussion ID components
-  def self.build_discussion_id(note)
-    [*build_discussion_id_base(note), SecureRandom.hex]
+  # To turn a list of notes into a list of discussions, they are grouped by discussion ID.
+  # When notes on a commit are displayed in context of a merge request that contains that commit,
+  # these notes are to be displayed as if they were part of one discussion, even though they were actually
+  # individual notes on the commit with different discussion IDs, so that it's clear that these are not
+  # notes on the merge request itself.
+  # To get these out-of-context notes to end up in the same discussion, we need to get them to return the same
+  # `discussion_id` when this grouping happens. To enable this, `Note#discussion_id` calls out
+  # to the `override_discussion_id` method on the appropriate `Discussion` subclass, as determined by
+  # the `discussion_class` method on `Note` or a subclass of `Note`.
+  # If no override is necessary, return `nil`.
+  # For the case described above, see `OutOfContextDiscussion.override_discussion_id`.
+  def self.override_discussion_id(note)
+    nil
   end
 
   def initialize(notes, noteable = nil)
@@ -97,20 +105,4 @@ class Discussion
   def reply_attributes
     first_note.slice(:type, :noteable_type, :noteable_id, :commit_id, :discussion_id)
   end
-
-  private
-
-  def update
-    # Do not select `Note.resolvable`, so that system notes remain in the collection
-    notes_relation = Note.where(id: notes.map(&:id))
-
-    yield(notes_relation)
-
-    # Set the notes array to the updated notes
-    @notes = notes_relation.fresh.to_a
-
-    self.class.memoized_values.each do |var|
-      instance_variable_set(:"@#{var}", nil)
-    end
-  end
 end

app/models/discussion_note.rb

@@ -5,6 +5,6 @@ class DiscussionNote < Note
   validates :noteable_type, inclusion: { in: NOTEABLE_TYPES }
 
   def discussion_class(*)
-    SimpleDiscussion
+    Discussion
   end
 end

app/models/individual_note_discussion.rb

 # A discussion to wrap a single `Note` note on the root of an issue, merge request,
-# commit, or snippet, that is not displayed as a discussion
+# commit, or snippet, that is not displayed as a discussion.
 class IndividualNoteDiscussion < Discussion
-  # Keep this method in sync with the `potentially_resolvable` scope on `ResolvableNote`
   def potentially_resolvable?
     false
   end

app/models/legacy_diff_discussion.rb

-# A discussion on merge request or commit diffs consisting of `LegacyDiffNote` notes
+# A discussion on merge request or commit diffs consisting of `LegacyDiffNote` notes.
+# All new diff discussions are of the type `DiffDiscussion`, but any diff discussions created
+# before the introduction of the new implementation still use `LegacyDiffDiscussion`.
 class LegacyDiffDiscussion < Discussion
   include DiscussionOnDiff
 
@@ -6,7 +8,6 @@ class LegacyDiffDiscussion < Discussion
     true
   end
 
-  # Keep this method in sync with the `potentially_resolvable` scope on `ResolvableNote`
   def potentially_resolvable?
     false
   end

app/models/legacy_diff_note.rb

-# A note on merge request or commit diffs, using the legacy implementation
+# A note on merge request or commit diffs, using the legacy implementation.
+# All new diff notes are of the type `DiffNote`, but any diff notes created
+# before the introduction of the new implementation still use `LegacyDiffNote`.
 class LegacyDiffNote < Note
   include NoteOnDiff
 

app/models/merge_request.rb

@@ -478,30 +478,6 @@ class MergeRequest < ActiveRecord::Base
 
   alias_method :discussion_notes, :related_notes
 
-  def resolvable_discussions
-    @resolvable_discussions ||= notes.resolvable.discussions
-  end
-
-  def discussions_resolvable?
-    resolvable_discussions.any?(&:resolvable?)
-  end
-
-  def discussions_resolved?
-    discussions_resolvable? && resolvable_discussions.none?(&:to_be_resolved?)
-  end
-
-  def discussions_to_be_resolved?
-    discussions_resolvable? && !discussions_resolved?
-  end
-
-  def discussions_to_be_resolved
-    @discussions_to_be_resolved ||= resolvable_discussions.select(&:to_be_resolved?)
-  end
-
-  def discussions_can_be_resolved_by?(user)
-    discussions_to_be_resolved.all? { |discussion| discussion.can_resolve?(user) }
-  end
-
   def mergeable_discussions_state?
     return true unless project.only_allow_merge_if_all_discussions_are_resolved?
 

app/models/note.rb

@@ -227,7 +227,8 @@ class Note < ActiveRecord::Base
 
   def discussion_class(noteable = nil)
     # When commit notes are rendered on an MR's Discussion page, they are
-    # displayed in one discussion instead of individually
+    # displayed in one discussion instead of individually.
+    # See also `#discussion_id` and `Discussion.override_discussion_id`.
     if noteable && noteable != self.noteable
       OutOfContextDiscussion
     else
@@ -235,6 +236,7 @@ class Note < ActiveRecord::Base
     end
   end
 
+  # See `Discussion.override_discussion_id` for details.
   def discussion_id(noteable = nil)
     discussion_class(noteable).override_discussion_id(self) || super()
   end

app/models/out_of_context_discussion.rb

-# A discussion to wrap a number of `Note` notes on the root of a commit when they
-# are displayed in context of a merge request as if they were part of a discussion.
+# When notes on a commit are displayed in the context of a merge request that contains that commit,
+# they are displayed as if they were a discussion.
+# This represents one of those discussions, consisting of `Note` notes.
 class OutOfContextDiscussion < Discussion
-  # To make sure all out-of-context notes are displayed in one discussion,
+  # Returns an array of discussion ID components
+  def self.build_discussion_id(note)
+    base_discussion_id(note)
+  end
+
+  # To make sure all out-of-context notes end up grouped as one discussion,
   # we override the discussion ID to be a newly generated but consistent ID.
   def self.override_discussion_id(note)
-    Digest::SHA1.hexdigest(build_discussion_id_base(note).join("-"))
+    discussion_id(note)
   end
 
-  # Keep this method in sync with the `potentially_resolvable` scope on `ResolvableNote`
   def potentially_resolvable?
     false
   end

app/models/sent_notification.rb

@@ -102,6 +102,8 @@ class SentNotification < ActiveRecord::Base
     if self.in_reply_to_discussion_id.present?
       attrs[:in_reply_to_discussion_id] = self.in_reply_to_discussion_id
     else
+      # Remove in GitLab 10.0, when we will not support replying to SentNotifications
+      # that don't have `in_reply_to_discussion_id` anymore.
       attrs.merge!(
         type: self.note_type,
 

app/models/simple_discussion.rb

-# A non-diff discussion on an issue, merge request, commit, or snippet, consisting of `DiscussionNote` notes
-class SimpleDiscussion < Discussion
-end

app/services/notes/build_service.rb

 module Notes
-  class BuildService < BaseService
+  class BuildService < ::BaseService
     def execute
       in_reply_to_discussion_id = params.delete(:in_reply_to_discussion_id)
       new_discussion = params.delete(:new_discussion)

app/services/notes/create_service.rb

 module Notes
-  class CreateService < BaseService
+  class CreateService < ::BaseService
     def execute
       merge_request_diff_head_sha = params.delete(:merge_request_diff_head_sha)
 

app/views/notify/note_merge_request_email.text.erb

-<%= render partial: 'note_email'%>
+<%= render 'note_email' %>

changelogs/unreleased/new-resolvable-discussion.yml

 ---
 title: Add option to start a new resolvable discussion in an MR
-merge_request: 
-author: 
+merge_request: 7527
+author:

db/migrate/20170308220217_add_index_to_note_original_discussion_id.rb

-# See http://doc.gitlab.com/ce/development/migration_style_guide.html
-# for more information on how to write migrations for GitLab.
-
-class AddIndexToNoteOriginalDiscussionId < ActiveRecord::Migration
-  include Gitlab::Database::MigrationHelpers
-
-  DOWNTIME = false
-
-  disable_ddl_transaction!
-
-  def up
-    add_concurrent_index :notes, :original_discussion_id
-  end
-
-  def down
-    remove_index :notes, :original_discussion_id if index_exists? :notes, :original_discussion_id
-  end
-end

db/schema.rb

@@ -736,7 +736,6 @@ ActiveRecord::Schema.define(version: 20170402231018) do
   add_index "notes", ["note"], name: "index_notes_on_note_trigram", using: :gin, opclasses: {"note"=>"gin_trgm_ops"}
   add_index "notes", ["noteable_id", "noteable_type"], name: "index_notes_on_noteable_id_and_noteable_type", using: :btree
   add_index "notes", ["noteable_type"], name: "index_notes_on_noteable_type", using: :btree
-  add_index "notes", ["original_discussion_id"], name: "index_notes_on_original_discussion_id", using: :btree
   add_index "notes", ["project_id", "noteable_type"], name: "index_notes_on_project_id_and_noteable_type", using: :btree
   add_index "notes", ["updated_at"], name: "index_notes_on_updated_at", using: :btree
 

spec/factories/notes.rb

@@ -25,17 +25,11 @@ FactoryGirl.define do
       end
     end
 
-    factory :discussion_note_on_issue, traits: [:on_issue], class: DiscussionNote do
-      association :project, :repository
-    end
+    factory :discussion_note_on_issue, traits: [:on_issue], class: DiscussionNote
 
-    factory :discussion_note_on_commit, traits: [:on_commit], class: DiscussionNote do
-      association :project, :repository
-    end
+    factory :discussion_note_on_commit, traits: [:on_commit], class: DiscussionNote
 
-    factory :legacy_diff_note_on_commit, traits: [:on_commit, :legacy_diff_note], class: LegacyDiffNote do
-      association :project, :repository
-    end
+    factory :legacy_diff_note_on_commit, traits: [:on_commit, :legacy_diff_note], class: LegacyDiffNote
 
     factory :legacy_diff_note_on_merge_request, traits: [:on_merge_request, :legacy_diff_note], class: LegacyDiffNote do
       association :project, :repository

spec/features/merge_requests/diff_notes_avatars_spec.rb

@@ -163,9 +163,9 @@ feature 'Diff note avatars', feature: true, js: true do
       end
 
       context 'multiple comments' do
-        let!(:notes) { create_list(:diff_note_on_merge_request, 3, project: project, noteable: merge_request, in_reply_to: note) }
-
         before do
+          create_list(:diff_note_on_merge_request, 3, project: project, noteable: merge_request, in_reply_to: note)
+
           visit diffs_namespace_project_merge_request_path(project.namespace, project, merge_request, view: view)
 
           wait_for_ajax

spec/mailers/notify_spec.rb

@@ -647,14 +647,14 @@ describe Notify do
       shared_examples 'a discussion note email' do |model|
         it_behaves_like 'it should have Gmail Actions links'
 
-        it 'is sent as the author' do
+        it 'is sent to the given recipient as the author' do
           sender = subject.header[:from].addrs[0]
-          expect(sender.display_name).to eq(note_author.name)
-          expect(sender.address).to eq(gitlab_sender)
-        end
 
-        it 'is sent to the given recipient' do
-          is_expected.to deliver_to recipient.notification_email
+          aggregate_failures do
+            expect(sender.display_name).to eq(note_author.name)
+            expect(sender.address).to eq(gitlab_sender)
+            expect(subject).to deliver_to(recipient.notification_email)
+          end
         end
 
         it 'contains the message from the note' do

spec/mailers/previews/notify_preview.rb

+class NotifyPreview < ActionMailer::Preview
+  def note_merge_request_email_for_individual_note
+    note_email(:note_merge_request_email) do
+      note = <<-MD.strip_heredoc
+        This is an individual note on a merge request :smiley:
+
+        In this notification email, we expect to see:
+
+        - The note contents (that's what you're looking at)
+        - A link to view this note on Gitlab
+        - An explanation for why the user is receiving this notification
+      MD
+
+      create_note(noteable_type: 'merge_request', noteable_id: merge_request.id, note: note)
+    end
+  end
+
+  def note_merge_request_email_for_discussion
+    note_email(:note_merge_request_email) do
+      note = <<-MD.strip_heredoc
+        This is a new discussion on a merge request :smiley:
+
+        In this notification email, we expect to see:
+
+        - A line saying who started this discussion
+        - The note contents (that's what you're looking at)
+        - A link to view this discussion on Gitlab
+        - An explanation for why the user is receiving this notification
+      MD
+
+      create_note(noteable_type: 'merge_request', noteable_id: merge_request.id, type: 'DiscussionNote', note: note)
+    end
+  end
+
+  def note_merge_request_email_for_diff_discussion
+    note_email(:note_merge_request_email) do
+      note = <<-MD.strip_heredoc
+        This is a new discussion on a merge request :smiley:
+
+        In this notification email, we expect to see:
+
+        - A line saying who started this discussion and on what file
+        - The diff
+        - The note contents (that's what you're looking at)
+        - A link to view this discussion on Gitlab
+        - An explanation for why the user is receiving this notification
+      MD
+
+      position = Gitlab::Diff::Position.new(
+        old_path: "files/ruby/popen.rb",
+        new_path: "files/ruby/popen.rb",
+        old_line: nil,
+        new_line: 14,
+        diff_refs: merge_request.diff_refs
+      )
+
+      create_note(noteable_type: 'merge_request', noteable_id: merge_request.id, type: 'DiffNote', position: position, note: note)
+    end
+  end
+
+  private
+
+  def project
+    @project ||= Project.find_by_full_path('gitlab-org/gitlab-test')
+  end
+
+  def issue
+    @issue ||= project.issues.last
+  end
+
+  def merge_request
+    @merge_request ||= project.merge_requests.find_by(source_branch: 'master', target_branch: 'feature')
+  end
+
+  def commit
+    @commit ||= project.commit('570e7b2abdd848b95f2f578043fc23bd6f6fd24d')
+  end
+
+  def user
+    @user ||= User.last
+  end
+
+  def note_body
+    <<-MD.strip_heredoc
+      Hello :smiley:
+
+      We expect a blank line between:
+      - The heading ("Adminstrator started...")
+      - The diff
+    MD
+  end
+
+  def create_note(params)
+    Notes::CreateService.new(project, user, params).execute
+  end
+
+  def note_email(method)
+    cleanup do
+      note = yield
+
+      Notify.public_send(method, user.id, note)
+    end
+  end
+
+  def cleanup
+    email = nil
+
+    ActiveRecord::Base.transaction do
+      email = yield
+      raise ActiveRecord::Rollback
+    end
+
+    email
+  end
+end

spec/models/concerns/discussion_on_diff_spec.rb

+require 'spec_helper'
+
+describe DiffDiscussion, DiscussionOnDiff, model: true do
+  subject { create(:diff_note_on_merge_request).to_discussion }
+
+  describe "#truncated_diff_lines" do
+    let(:truncated_lines) { subject.truncated_diff_lines }
+
+    context "when diff is greater than allowed number of truncated diff lines " do
+      it "returns fewer lines"  do
+        expect(subject.diff_lines.count).to be > described_class::NUMBER_OF_TRUNCATED_DIFF_LINES
+
+        expect(truncated_lines.count).to be <= described_class::NUMBER_OF_TRUNCATED_DIFF_LINES
+      end
+    end
+
+    context "when some diff lines are meta" do
+      it "returns no meta lines"  do
+        expect(subject.diff_lines).to include(be_meta)
+        expect(truncated_lines).not_to include(be_meta)
+      end
+    end
+  end
+end

spec/models/concerns/resolvable_discussion_spec.rb

@@ -5,8 +5,9 @@ describe Discussion, ResolvableDiscussion, models: true do
 
   let(:first_note) { create(:discussion_note_on_merge_request) }
   let(:merge_request) { first_note.noteable }
-  let(:second_note) { create(:discussion_note_on_merge_request, in_reply_to: first_note) }
-  let(:third_note) { create(:discussion_note_on_merge_request) }
+  let(:project) { first_note.project }
+  let(:second_note) { create(:discussion_note_on_merge_request, noteable: merge_request, project: project, in_reply_to: first_note) }
+  let(:third_note) { create(:discussion_note_on_merge_request, noteable: merge_request, project: project) }
 
   describe "#resolvable?" do
     context "when potentially resolvable" do

spec/models/concerns/resolvable_note_spec.rb

 require 'spec_helper'
 
 describe Note, ResolvableNote, models: true do
-  subject { create(:discussion_note_on_merge_request) }
+  let(:project) { create(:project) }
+  let(:merge_request) { create(:merge_request, source_project: project) }
+  subject { create(:discussion_note_on_merge_request, noteable: merge_request, project: project) }
 
   context 'resolvability scopes' do
-    let!(:note1) { create(:note) }
-    let!(:note2) { create(:diff_note_on_commit) }
-    let!(:note3) { create(:diff_note_on_merge_request, :resolved) }
-    let!(:note4) { create(:discussion_note_on_merge_request) }
-    let!(:note5) { create(:discussion_note_on_issue) }
-    let!(:note6) { create(:discussion_note_on_merge_request, :system) }
+    let!(:note1) { create(:note, project: project) }
+    let!(:note2) { create(:diff_note_on_commit, project: project) }
+    let!(:note3) { create(:diff_note_on_merge_request, :resolved, noteable: merge_request, project: project) }
+    let!(:note4) { create(:discussion_note_on_merge_request, noteable: merge_request, project: project) }
+    let!(:note5) { create(:discussion_note_on_issue, project: project) }
+    let!(:note6) { create(:discussion_note_on_merge_request, :system, noteable: merge_request, project: project) }
 
     describe '.potentially_resolvable' do
       it 'includes diff and discussion notes on merge requests' do
@@ -38,9 +40,9 @@ describe Note, ResolvableNote, models: true do
 
   describe ".resolve!" do
     let(:current_user) { create(:user) }
-    let!(:commit_note) { create(:diff_note_on_commit) }
-    let!(:resolved_note) { create(:discussion_note_on_merge_request, :resolved) }
-    let!(:unresolved_note) { create(:discussion_note_on_merge_request) }
+    let!(:commit_note) { create(:diff_note_on_commit, project: project) }
+    let!(:resolved_note) { create(:discussion_note_on_merge_request, :resolved, noteable: merge_request, project: project) }
+    let!(:unresolved_note) { create(:discussion_note_on_merge_request, noteable: merge_request, project: project) }
 
     before do
       described_class.resolve!(current_user)
@@ -59,7 +61,7 @@ describe Note, ResolvableNote, models: true do
   end
 
   describe ".unresolve!" do
-    let!(:resolved_note) { create(:discussion_note_on_merge_request, :resolved) }
+    let!(:resolved_note) { create(:discussion_note_on_merge_request, :resolved, noteable: merge_request, project: project) }
 
     before do
       described_class.unresolve!

spec/models/diff_discussion_spec.rb

@@ -4,8 +4,10 @@ describe DiffDiscussion, model: true do
   subject { described_class.new([first_note, second_note, third_note]) }
 
   let(:first_note) { create(:diff_note_on_merge_request) }
-  let(:second_note) { create(:diff_note_on_merge_request, in_reply_to: first_note) }
-  let(:third_note) { create(:diff_note_on_merge_request, in_reply_to: first_note) }
+  let(:merge_request) { first_note.noteable }
+  let(:project) { first_note.project }
+  let(:second_note) { create(:diff_note_on_merge_request, noteable: merge_request, project: project, in_reply_to: first_note) }
+  let(:third_note) { create(:diff_note_on_merge_request, noteable: merge_request, project: project, in_reply_to: first_note) }
 
   describe '#reply_attributes' do
     it 'includes position and original_position' do
@@ -14,23 +16,4 @@ describe DiffDiscussion, model: true do
       expect(attributes[:original_position]).to eq(first_note.original_position.to_json)
     end
   end
-
-  describe "#truncated_diff_lines" do
-    let(:truncated_lines) { subject.truncated_diff_lines }
-
-    context "when diff is greater than allowed number of truncated diff lines " do
-      it "returns fewer lines"  do
-        expect(subject.diff_lines.count).to be > described_class::NUMBER_OF_TRUNCATED_DIFF_LINES
-
-        expect(truncated_lines.count).to be <= described_class::NUMBER_OF_TRUNCATED_DIFF_LINES
-      end
-    end
-
-    context "when some diff lines are meta" do
-      it "returns no meta lines"  do
-        expect(subject.diff_lines).to include(be_meta)
-        expect(truncated_lines).not_to include(be_meta)
-      end
-    end
-  end
 end

spec/models/discussion_note_spec.rb

-require 'spec_helper'
-
-describe DiscussionNote, models: true do
-end

spec/models/discussion_spec.rb

@@ -3,15 +3,15 @@ require 'spec_helper'
 describe Discussion, model: true do
   subject { described_class.new([first_note, second_note, third_note]) }
 
-  let(:first_note) { create(:discussion_note_on_merge_request) }
+  let(:first_note) { create(:diff_note_on_merge_request) }
   let(:merge_request) { first_note.noteable }
-  let(:second_note) { create(:discussion_note_on_merge_request, in_reply_to: first_note) }
-  let(:third_note) { create(:discussion_note_on_merge_request) }
+  let(:second_note) { create(:diff_note_on_merge_request, in_reply_to: first_note) }
+  let(:third_note) { create(:diff_note_on_merge_request) }
 
   describe '.build' do
     it 'returns a discussion of the right type' do
       discussion = described_class.build([first_note, second_note], merge_request)
-      expect(discussion).to be_a(SimpleDiscussion)
+      expect(discussion).to be_a(DiffDiscussion)
       expect(discussion.notes.count).to be(2)
       expect(discussion.first_note).to be(first_note)
       expect(discussion.noteable).to be(merge_request)
@@ -22,8 +22,8 @@ describe Discussion, model: true do
     it 'returns an array of discussions of the right type' do
       discussions = described_class.build_collection([first_note, second_note, third_note], merge_request)
       expect(discussions).to eq([
-        SimpleDiscussion.new([first_note, second_note], merge_request),
-        SimpleDiscussion.new([third_note], merge_request)
+        DiffDiscussion.new([first_note, second_note], merge_request),
+        DiffDiscussion.new([third_note], merge_request)
       ])
     end
   end

spec/models/individual_note_discussion_spec.rb

-require 'spec_helper'
-
-describe IndividualNoteDiscussion, models: true do
-end

spec/models/merge_request_spec.rb

@@ -1224,182 +1224,6 @@ describe MergeRequest, models: true do
     end
   end
 
-  context "discussion status" do
-    let(:first_discussion) { create(:discussion_note_on_merge_request).to_discussion }
-    let(:second_discussion) { create(:discussion_note_on_merge_request).to_discussion }
-    let(:third_discussion) { create(:discussion_note_on_merge_request).to_discussion }
-
-    before do
-      allow(subject).to receive(:resolvable_discussions).and_return([first_discussion, second_discussion, third_discussion])
-    end
-
-    describe "#discussions_resolvable?" do
-      context "when all discussions are unresolvable" do
-        before do
-          allow(first_discussion).to receive(:resolvable?).and_return(false)
-          allow(second_discussion).to receive(:resolvable?).and_return(false)
-          allow(third_discussion).to receive(:resolvable?).and_return(false)
-        end
-
-        it "returns false" do
-          expect(subject.discussions_resolvable?).to be false
-        end
-      end
-
-      context "when some discussions are unresolvable and some discussions are resolvable" do
-        before do
-          allow(first_discussion).to receive(:resolvable?).and_return(true)
-          allow(second_discussion).to receive(:resolvable?).and_return(false)
-          allow(third_discussion).to receive(:resolvable?).and_return(true)
-        end
-
-        it "returns true" do
-          expect(subject.discussions_resolvable?).to be true
-        end
-      end
-
-      context "when all discussions are resolvable" do
-        before do
-          allow(first_discussion).to receive(:resolvable?).and_return(true)
-          allow(second_discussion).to receive(:resolvable?).and_return(true)
-          allow(third_discussion).to receive(:resolvable?).and_return(true)
-        end
-
-        it "returns true" do
-          expect(subject.discussions_resolvable?).to be true
-        end
-      end
-    end
-
-    describe "#discussions_resolved?" do
-      context "when discussions are not resolvable" do
-        before do
-          allow(subject).to receive(:discussions_resolvable?).and_return(false)
-        end
-
-        it "returns false" do
-          expect(subject.discussions_resolved?).to be false
-        end
-      end
-
-      context "when discussions are resolvable" do
-        before do
-          allow(subject).to receive(:discussions_resolvable?).and_return(true)
-
-          allow(first_discussion).to receive(:resolvable?).and_return(true)
-          allow(second_discussion).to receive(:resolvable?).and_return(false)
-          allow(third_discussion).to receive(:resolvable?).and_return(true)
-        end
-
-        context "when all resolvable discussions are resolved" do
-          before do
-            allow(first_discussion).to receive(:resolved?).and_return(true)
-            allow(third_discussion).to receive(:resolved?).and_return(true)
-          end
-
-          it "returns true" do
-            expect(subject.discussions_resolved?).to be true
-          end
-        end
-
-        context "when some resolvable discussions are not resolved" do
-          before do
-            allow(first_discussion).to receive(:resolved?).and_return(true)
-            allow(third_discussion).to receive(:resolved?).and_return(false)
-          end
-
-          it "returns false" do
-            expect(subject.discussions_resolved?).to be false
-          end
-        end
-      end
-    end
-
-    describe "#discussions_to_be_resolved?" do
-      context "when discussions are not resolvable" do
-        before do
-          allow(subject).to receive(:discussions_resolvable?).and_return(false)
-        end
-
-        it "returns false" do
-          expect(subject.discussions_to_be_resolved?).to be false
-        end
-      end
-
-      context "when discussions are resolvable" do
-        before do
-          allow(subject).to receive(:discussions_resolvable?).and_return(true)
-
-          allow(first_discussion).to receive(:resolvable?).and_return(true)
-          allow(second_discussion).to receive(:resolvable?).and_return(false)
-          allow(third_discussion).to receive(:resolvable?).and_return(true)
-        end
-
-        context "when all resolvable discussions are resolved" do
-          before do
-            allow(first_discussion).to receive(:resolved?).and_return(true)
-            allow(third_discussion).to receive(:resolved?).and_return(true)
-          end
-
-          it "returns false" do
-            expect(subject.discussions_to_be_resolved?).to be false
-          end
-        end
-
-        context "when some resolvable discussions are not resolved" do
-          before do
-            allow(first_discussion).to receive(:resolved?).and_return(true)
-            allow(third_discussion).to receive(:resolved?).and_return(false)
-          end
-
-          it "returns true" do
-            expect(subject.discussions_to_be_resolved?).to be true
-          end
-        end
-      end
-    end
-
-    describe "#discussions_to_be_resolved" do
-      before do
-        allow(first_discussion).to receive(:to_be_resolved?).and_return(true)
-        allow(second_discussion).to receive(:to_be_resolved?).and_return(false)
-        allow(third_discussion).to receive(:to_be_resolved?).and_return(false)
-      end
-
-      it 'includes only discussions that need to be resolved' do
-        expect(subject.discussions_to_be_resolved).to eq([first_discussion])
-      end
-    end
-
-    describe '#discussions_can_be_resolved_by?' do
-      let(:user) { build(:user) }
-
-      context 'all discussions can be resolved by the user' do
-        before do
-          allow(first_discussion).to receive(:can_resolve?).with(user).and_return(true)
-          allow(second_discussion).to receive(:can_resolve?).with(user).and_return(true)
-          allow(third_discussion).to receive(:can_resolve?).with(user).and_return(true)
-        end
-
-        it 'allows a user to resolve the discussions' do
-          expect(subject.discussions_can_be_resolved_by?(user)).to be(true)
-        end
-      end
-
-      context 'one discussion cannot be resolved by the user' do
-        before do
-          allow(first_discussion).to receive(:can_resolve?).with(user).and_return(true)
-          allow(second_discussion).to receive(:can_resolve?).with(user).and_return(true)
-          allow(third_discussion).to receive(:can_resolve?).with(user).and_return(false)
-        end
-
-        it 'allows a user to resolve the discussions' do
-          expect(subject.discussions_can_be_resolved_by?(user)).to be(false)
-        end
-      end
-    end
-  end
-
   describe '#conflicts_can_be_resolved_in_ui?' do
     def create_merge_request(source_branch)
       create(:merge_request, source_branch: source_branch, target_branch: 'conflict-start') do |mr|

spec/models/note_spec.rb

@@ -250,7 +250,7 @@ describe Note, models: true do
     let!(:note2) { create(:discussion_note_on_merge_request, in_reply_to: note) }
     let(:merge_request) { note.noteable }
 
-    it 'returns a discussion with multiple note' do
+    it 'returns a discussion with multiple notes' do
       discussion = merge_request.notes.find_discussion(note.discussion_id)
 
       expect(discussion).not_to be_nil
@@ -379,57 +379,57 @@ describe Note, models: true do
 
   describe '#can_be_discussion_note?' do
     context 'for a note on a merge request' do
-      let(:note) { build(:note_on_merge_request) }
-
       it 'returns true' do
+        note = build(:note_on_merge_request)
+
         expect(note.can_be_discussion_note?).to be_truthy
       end
     end
 
     context 'for a note on an issue' do
-      let(:note) { build(:note_on_issue) }
-
       it 'returns true' do
+        note = build(:note_on_issue)
+
         expect(note.can_be_discussion_note?).to be_truthy
       end
     end
 
     context 'for a note on a commit' do
-      let(:note) { build(:note_on_commit) }
-
       it 'returns true' do
+        note = build(:note_on_commit)
+
         expect(note.can_be_discussion_note?).to be_truthy
       end
     end
 
     context 'for a note on a snippet' do
-      let(:note) { build(:note_on_project_snippet) }
-
       it 'returns true' do
+        note = build(:note_on_project_snippet)
+
         expect(note.can_be_discussion_note?).to be_truthy
       end
     end
 
     context 'for a diff note on merge request' do
-      let(:note) { build(:diff_note_on_merge_request) }
-
       it 'returns false' do
+        note = build(:diff_note_on_merge_request)
+
         expect(note.can_be_discussion_note?).to be_falsey
       end
     end
 
     context 'for a diff note on commit' do
-      let(:note) { build(:diff_note_on_commit) }
-
       it 'returns false' do
+        note = build(:diff_note_on_commit)
+
         expect(note.can_be_discussion_note?).to be_falsey
       end
     end
 
     context 'for a discussion note' do
-      let(:note) { build(:discussion_note_on_merge_request) }
-
       it 'returns false' do
+        note = build(:discussion_note_on_merge_request)
+
         expect(note.can_be_discussion_note?).to be_falsey
       end
     end

spec/models/out_of_context_discussion_spec.rb

-require 'spec_helper'
-
-describe OutOfContextDiscussion, model: true do
-end

spec/models/simple_discussion_spec.rb

-require 'spec_helper'
-
-describe SimpleDiscussion, model: true do
-  subject { create(:discussion_note_on_issue).to_discussion }
-
-  describe '#reply_attributes' do
-    it 'includes discussion_id' do
-      expect(subject.reply_attributes[:discussion_id]).to eq(subject.id)
-    end
-  end
-end