require File.join(File.dirname(__FILE__), '..', 'spec_helper')

describe ProjectionRelation do
  before do
    @relation1 = TableRelation.new(:foo)
    @relation2 = TableRelation.new(:bar)
    @attribute1 = @relation1[:id]
    @attribute2 = @relation2[:id]
  end
  
  describe '==' do
    it "obtains if the relations and attributes are identical" do
      ProjectionRelation.new(@relation1, @attribute1, @attribute2).should == ProjectionRelation.new(@relation1, @attribute1, @attribute2)
      ProjectionRelation.new(@relation1, @attribute1).should_not == ProjectionRelation.new(@relation2, @attribute1)
      ProjectionRelation.new(@relation1, @attribute1).should_not == ProjectionRelation.new(@relation1, @attribute2)
    end
  end
  
  describe '#qualify' do
    it "distributes over teh relation and attributes" do
      ProjectionRelation.new(@relation1, @attribute1).qualify. \
        should == ProjectionRelation.new(@relation1.qualify, @attribute1.qualify)
    end
  end
  
  describe '#to_sql' do
    it "manufactures sql with a limited select clause" do
      ProjectionRelation.new(@relation1, @attribute1).to_sql.to_s.should == SelectBuilder.new do
        select do
          column :foo, :id
        end
        from :foo
      end.to_s
    end
  end
end