show existing message count when reporting posted messages

When Developer see that there are 0 messages posted in the log, but pronto still is failed, there is no idea what's going on.

Added more insights in the message in order to prevent such confusion.

lib/pronto/formatter/git_formatter.rb

@@ -10,7 +10,7 @@ def format(messages, repo, patches)
 
         approve_pull_request(comments.count, additions.count, client) if defined?(self.approve_pull_request)
 
-        "#{additions.count} Pronto messages posted to #{pretty_name}"
+        "#{additions.count} Pronto messages posted to #{pretty_name} (#{existing.count} existing)"
       end
 
       def client_module

spec/pronto/formatter/github_formatter_spec.rb

@@ -7,9 +7,11 @@ module Formatter
         subject { formatter.format(messages, repo, nil) }
 
         let(:repo) { Git::Repository.new('spec/fixtures/test.git') }
-        let(:published_comments_msg) { "%{count} Pronto messages posted to #{formatter.pretty_name}" }
+        let(:published_comments_msg) do
+          "%<count>i Pronto messages posted to #{formatter.pretty_name} (%<existing_count>i existing)"
+        end
 
-        context 'with duplicates' do
+        context 'with duplicates in the new messages' do
           let(:messages) { [message, message] }
           let(:message) { Message.new('path/to', line, :warning, 'crucial') }
           let(:line) { double(new_lineno: 1, commit_sha: '123', position: nil) }
@@ -25,7 +27,46 @@ module Formatter
               .should_receive(:create_commit_comment)
               .once
 
-            subject.should eq format(published_comments_msg, count: 1)
+            subject.should eq format(published_comments_msg, count: 1, existing_count: 0)
+          end
+        end
+
+        context 'with duplicates in the existed messages' do
+          let(:messages) { [message] }
+          let(:message) { Message.new('path/to', line, :warning, 'crucial') }
+          let(:line) { double(new_lineno: 1, commit_sha: '123', position: nil) }
+
+          before { line.stub(:commit_line).and_return(line) }
+
+          specify do
+            Octokit::Client.any_instance
+              .should_receive(:commit_comments)
+              .once
+              .and_return([double(body: 'crucial', path: 'path/to', position: nil)])
+
+            Octokit::Client.any_instance.should_not_receive(:create_commit_comment)
+
+            subject.should eq format(published_comments_msg, count: 0, existing_count: 1)
+          end
+        end
+
+        context 'with one duplicate and one non duplicated messages' do
+          let(:messages) { [message, existed_message] }
+          let(:message) { Message.new('path/to', line, :warning, 'crucial') }
+          let(:existed_message) { Message.new('path/to', line, :warning, 'existed') }
+          let(:line) { double(new_lineno: 1, commit_sha: '123', position: nil) }
+
+          before { line.stub(:commit_line).and_return(line) }
+
+          specify do
+            Octokit::Client.any_instance
+              .should_receive(:commit_comments)
+              .once
+              .and_return([double(body: 'existed', path: 'path/to', position: nil)])
+
+            Octokit::Client.any_instance.should_receive(:create_commit_comment).once
+
+            subject.should eq format(published_comments_msg, count: 1, existing_count: 1)
           end
         end
 
@@ -51,7 +92,7 @@ module Formatter
               .should_receive(:create_commit_comment)
               .twice
 
-            subject.should eq format(published_comments_msg, count: 2)
+            subject.should eq format(published_comments_msg, count: 2, existing_count: 0)
           end
         end
       end