post_spec.rb

# Test 
it 'finds the 5 most recent approved comments for the post' do
  ret = [mock_model(Comment)]
  comments = []
  comments.should_receive(:find_recent).with(hash_including(:limit => 5)).and_return(ret)
  post = mock_model(Post)
  post.stub!(:approved_comments).and_return(comments)
  CommentActivity.new(post).comments.should == ret
end


# $ spec spec/models/comment_activity_spec.rb -cf specdoc

CommentActivity#comments
- finds the 5 most recent approved comments for the post
- is memoized to avoid excess hits to the DB

Finished in 0.056793 seconds

2 examples, 0 failures

## A failing Test
The problem in my opinion is that the test is testing the implementation, not the behavior. but Im new to rails so I can missing some points


  context "find recent comments" do
    before :each do      
      @comments = []
      (1..10).each do |n|
        @comments << Comment.create(valid_comment_attributes(:created_at => Time.now - n * (60 * 60 * 24)))
      end
    end
    
    it "should have the comment activity sorted by when they were created" do
      comment_activity = CommentActivity.find_recent 
      comment_activity.first.post.should == @comments.first.post
    end
    
    it do
      comment_activity = CommentActivity.find_recent
      comment_activity.should have_exactly(5).posts
    end
  end

The error

Error

 ActiveRecord::StatementInvalid in Admin/dashboardController#show

PGError: ERROR:  for SELECT DISTINCT, ORDER BY expressions must appear in select list
LINE 1: ...comments ON comments.post_id = posts.id  ORDER BY comments.c...
                                                             ^
: SELECT distinct posts.* FROM "posts"  INNER JOIN comments ON comments.post_id = posts.id  ORDER BY comments.created_at DESC LIMIT 5

Application Trace | Framework Trace | Full Trace

/usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/connection_adapters/abstract_adapter.rb:219:in `log'
/usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/connection_adapters/postgresql_adapter.rb:550:in `execute'
/usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/connection_adapters/postgresql_adapter.rb:1037:in `select_raw'
/usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/connection_adapters/postgresql_adapter.rb:1024:in `select'
/usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/connection_adapters/abstract/database_statements.rb:7:in `select_all_without_query_cache'
/usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/connection_adapters/abstract/query_cache.rb:60:in `select_all'
/usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/connection_adapters/abstract/query_cache.rb:81:in `cache_sql'
/usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/connection_adapters/abstract/query_cache.rb:60:in `select_all'
/usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/base.rb:661:in `find_by_sql'
/usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/base.rb:1548:in `find_every'
/usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/base.rb:615:in `find'
/home/pdelgallego/github/fix_enki/app/models/comment_activity.rb:18:in `find_recent'
/home/pdelgallego/github/fix_enki/app/controllers/admin/dashboard_controller.rb:4:in `show'