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

describe Relation do
  before do
    @relation1 = TableRelation.new(:foo)
    @relation2 = TableRelation.new(:bar)
    @attribute1 = Attribute.new(@relation1, :id)
    @attribute2 = Attribute.new(@relation1, :name)
  end
  
  describe Relation, 'joins' do
    describe Relation, '<=>' do
      it "manufactures an inner join operation between those two relations" do
        (@relation1 <=> @relation2).should == InnerJoinOperation.new(@relation1, @relation2)
      end
    end
    
    describe Relation, '<<' do
      it "manufactures a left outer join operation between those two relations" do
        (@relation1 << @relation2).should == LeftOuterJoinOperation.new(@relation1, @relation2)
      end      
    end
  end
  
  describe Relation, '[]' do
    it "manufactures an attribute when given a symbol" do
      @relation1[:id].should be_eql(Attribute.new(@relation1, :id))
    end
    
    it "manufactures a range relation when given a range" do
      @relation1[1..2].should == RangeRelation.new(@relation1, 1..2)
    end
    
    it "raises an error if the named attribute is not part of the relation" do
      pending
    end
  end
  
  describe Relation, '#include?' do
    it "manufactures an inclusion predicate" do
      @relation1.include?(@attribute1).should == RelationInclusionPredicate.new(@attribute1, @relation1)
    end
  end
  
  describe Relation, '#project' do
    it "only allows projecting attributes in the relation" do
      pending
    end
    
    it "collapses identical projections" do
      pending
    end
    
    it "manufactures a projection relation" do
      @relation1.project(@attribute1, @attribute2).should == ProjectionRelation.new(@relation1, @attribute1, @attribute2)
    end
  end
  
  describe Relation, '#select' do
    before do
      @predicate = EqualityPredicate.new(@attribute1, @attribute2)
    end
    
    it "manufactures a selection relation" do
      @relation1.select(@attribute1, @attribute2).should == SelectionRelation.new(@relation1, @attribute1, @attribute2)
    end
  end
  
  describe Relation, 'order' do
    it "manufactures an order relation" do
      @relation1.order(@attribute1, @attribute2).should == OrderRelation.new(@relation1, @attribute1, @attribute2)
    end
  end
end