readable_dictionary.rb

shared_examples 'readable dictionary' do
  let(:uuid1) { uuid }
  let(:uuid2) { uuid }
  let(:uuid3) { uuid }
  let(:cf) { dictionary.class.column_family.column_family }

  context 'without row in memory' do

    describe '#each_pair' do

      it 'should load columns in batches and yield them' do
        connection.should_receive(:execute).
          with("SELECT FIRST 2 * FROM #{cf} WHERE ? = ? LIMIT 1", :blog_id, 1).
          and_return result_stub('blog_id' => 1, uuid1 => 1, uuid2 => 2)
        connection.should_receive(:execute).
          with("SELECT FIRST 2 ?..? FROM #{cf} WHERE ? = ? LIMIT 1", uuid2, '', :blog_id, 1).
          and_return result_stub('blog_id' => 1, uuid2 => 2, uuid3 => 3)
        connection.should_receive(:execute).
          with("SELECT FIRST 2 ?..? FROM #{cf} WHERE ? = ? LIMIT 1", uuid3, '', :blog_id, 1).
          and_return result_stub({'blog_id' => 1})
        hash = {}
        dictionary.each_pair do |key, value|
          hash[key] = value
        end
        hash.should == {uuid1 => 1, uuid2 => 2, uuid3 => 3}
      end

    end

    describe '#[]' do

      it 'should load column from cassandra' do
        connection.stub(:execute).
          with("SELECT ? FROM #{cf} WHERE ? = ? LIMIT 1", [uuid1], :blog_id, 1).
          and_return result_stub(uuid1 => 1)
        dictionary[uuid1].should == 1
      end

    end

    describe '#slice' do
      it 'should load columns from data store' do
        connection.stub(:execute).
          with("SELECT ? FROM #{cf} WHERE ? = ? LIMIT 1", [uuid1,uuid2], :blog_id, 1).
          and_return result_stub(uuid1 => 1, uuid2 => 2)
        dictionary.slice(uuid1, uuid2).should == {uuid1 => 1, uuid2 => 2}
      end
    end

    describe '#keys' do
      it 'should load keys from data store' do
        connection.should_receive(:execute).
          with("SELECT FIRST 2 * FROM #{cf} WHERE ? = ? LIMIT 1", :blog_id, 1).
          and_return result_stub('blog_id' => 1, uuid1 => 1, uuid2 => 2)
        connection.should_receive(:execute).
          with("SELECT FIRST 2 ?..? FROM #{cf} WHERE ? = ? LIMIT 1", uuid2, '', :blog_id, 1).
          and_return result_stub('blog_id' => 1, uuid2 => 2, uuid3 => 3)
        connection.should_receive(:execute).
          with("SELECT FIRST 2 ?..? FROM #{cf} WHERE ? = ? LIMIT 1", uuid3, '', :blog_id, 1).
          and_return result_stub({'blog_id' => 1})
        dictionary.keys.should == [uuid1, uuid2, uuid3]
      end
    end

    describe '#values' do
      it 'should load values from data store' do
        connection.should_receive(:execute).
          with("SELECT FIRST 2 * FROM #{cf} WHERE ? = ? LIMIT 1", :blog_id, 1).
          and_return result_stub('blog_id' => 1, uuid1 => 1, uuid2 => 2)
        connection.should_receive(:execute).
          with("SELECT FIRST 2 ?..? FROM #{cf} WHERE ? = ? LIMIT 1", uuid2, '', :blog_id, 1).
          and_return result_stub('blog_id' => 1, uuid2 => 2, uuid3 => 3)
        connection.should_receive(:execute).
          with("SELECT FIRST 2 ?..? FROM #{cf} WHERE ? = ? LIMIT 1", uuid3, '', :blog_id, 1).
          and_return result_stub({'blog_id' => 1})
        dictionary.values.should == [1, 2, 3]
      end
    end

    describe '#first' do
      it 'should load value from data store' do
        connection.should_receive(:execute).
          with("SELECT FIRST 1 * FROM #{cf} WHERE ? = ? LIMIT 1", :blog_id, 1).
          and_return result_stub('blog_id' => 1, uuid1 => 1)
        dictionary.first.should == [uuid1, 1]
      end
    end

    describe '#last' do
      it 'should load value from data store' do
        connection.should_receive(:execute).
          with("SELECT FIRST 1 REVERSED * FROM #{cf} WHERE ? = ? LIMIT 1", :blog_id, 1).
          and_return result_stub('blog_id' => 1, uuid3 => 3)
        dictionary.last.should == [uuid3, 3]
      end
    end

  end

  context 'with data loaded in memory' do
    before do
      connection.stub(:execute).
        with("SELECT FIRST 2 * FROM #{cf} WHERE ? = ? LIMIT 1", :blog_id, 1).
        and_return result_stub('blog_id' => 1, uuid1 => 1, uuid2 => 2)
      connection.stub(:execute).
        with("SELECT FIRST 2 ?..? FROM #{cf} WHERE ? = ? LIMIT 1", uuid2, '', :blog_id, 1).
        and_return result_stub('blog_id' => 1, uuid2 => 2, uuid3 => 3)
      connection.stub(:execute).
        with("SELECT FIRST 2 ?..? FROM #{cf} WHERE ? = ? LIMIT 1", uuid3, '', :blog_id, 1).
        and_return result_stub({'blog_id' => 1})
      dictionary.load
      connection.should_not_receive(:execute)
    end

    describe '#each_pair' do
      it 'should yield data from memory' do
        hash = {}
        dictionary.each_pair do |key, value|
          hash[key] = value
        end
        hash.should == {uuid1 => 1, uuid2 => 2, uuid3 => 3}
      end
    end

    describe '#[]' do
      it 'should return value from memory' do
        dictionary[uuid1].should == 1
      end
    end

    describe '#slice' do
      it 'should return slice of data in memory' do
        dictionary.slice(uuid1, uuid2).should == {uuid1 => 1, uuid2 => 2}
      end
    end

    describe '#first' do
      it 'should return first element in memory' do
        dictionary.first.should == [uuid1, 1]
      end
    end

    describe '#last' do
      it 'should return first element in memory' do
        dictionary.last.should == [uuid3, 3]
      end
    end

    describe '#keys' do
      it 'should return keys from memory' do
        dictionary.keys.should == [uuid1, uuid2, uuid3]
      end
    end

    describe '#values' do
      it 'should return values from memory' do
        dictionary.values.should == [1, 2, 3]
      end
    end
  end

  describe '::load' do
    let :comments do
      [
        {'user' => 'Cequel User', 'comment' => 'How do I load multiple rows?'},
        {'user' => 'Mat Brown', 'comment' => 'Just use the ::load class method'}
      ]
    end

    it 'should load all rows in one query' do
      connection.stub(:execute).
        with(
          'SELECT * FROM post_comments WHERE ? IN (?)',
          'post_id', [1, 2]
        ).and_return result_stub(
          *comments.each_with_index.
            map { |comment, i| {'post_id' => i+1, i+4 => comment.to_json} }
          )
      rows = PostComments.load(1, 2)
      rows.map { |row| row.post_id }.should == [1, 2]
      rows.map { |row| row.values.first }.should == comments
    end
  end

  private

  def uuid
    SimpleUUID::UUID.new.to_guid
  end
end