Provide accessor for the draft comment

app/models/bubble/messages.rb

@@ -3,9 +3,35 @@ module Bubble::Messages
 
   included do
     has_many :messages, -> { chronologically }, dependent: :destroy
+    after_save :capture_draft_comment
   end
 
   def capture(messageable)
     messages.create! messageable: messageable
   end
+
+  def draft_comment
+    find_or_build_initial_comment.body_plain_text
+  end
+
+  def draft_comment=(body)
+    if body.present?
+      @draft_comment = body
+    else
+      messages.comments.destroy_all
+    end
+  end
+
+  private
+    def find_or_build_initial_comment
+      message = messages.comments.first || messages.new(messageable: Comment.new)
+      message.comment
+    end
+
+    def capture_draft_comment
+      if @draft_comment.present?
+        find_or_build_initial_comment.update! body: @draft_comment, creator: creator
+      end
+      @draft_comment = nil
+    end
 end

test/models/bubble/messages_test.rb

@@ -0,0 +1,46 @@
+require "test_helper"
+
+class Bubble::MessagesTest < ActiveSupport::TestCase
+  test "creating a bubble does not create a message by default" do
+    bubble = buckets(:writebook).bubbles.create! creator: users(:kevin), title: "New"
+
+    assert_empty bubble.messages
+  end
+
+  test "creating a bubble with an initial draft comment" do
+    bubble = buckets(:writebook).bubbles.create! creator: users(:kevin), title: "New",
+      draft_comment: "This is a comment"
+
+    assert_equal 1, bubble.messages.count
+    assert_equal "This is a comment", bubble.draft_comment.strip
+  end
+
+  test "updating the draft comment" do
+    bubble = buckets(:writebook).bubbles.create! creator: users(:kevin), title: "New",
+      draft_comment: "This is a comment"
+
+    bubble.update! draft_comment: "This is an updated comment"
+
+    assert_equal 1, bubble.messages.count
+    assert_equal "This is an updated comment", bubble.draft_comment.strip
+  end
+
+  test "setting the draft comment to be blank removes it" do
+    bubble = buckets(:writebook).bubbles.create! creator: users(:kevin), title: "New",
+      draft_comment: "This is a comment"
+
+    bubble.update! draft_comment: " "
+
+    assert bubble.messages.first.nil?
+  end
+
+  test "omitting the draft comment does not remove it" do
+    bubble = buckets(:writebook).bubbles.create! creator: users(:kevin), title: "New",
+      draft_comment: "This is a comment"
+
+    bubble.update! title: "Newer"
+
+    assert_equal 1, bubble.messages.count
+    assert_equal "This is a comment", bubble.draft_comment.strip
+  end
+end