1 files changed, 81 insertions, 0 deletions
diff --git a/spec/arel/unit/relations/projection_spec.rb b/spec/arel/unit/relations/projection_spec.rb
new file mode 100644
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+++ b/spec/arel/unit/relations/projection_spec.rb
@@ -0,0 +1,81 @@
+require File.join(File.dirname(__FILE__), '..', '..', '..', 'spec_helper')
+
+module Arel
+  describe Projection do
+    before do
+      @relation = Table.new(:users)
+      @attribute = @relation[:id]
+    end
+    
+    describe '#attributes' do
+      before do
+        @projection = Projection.new(@relation, @attribute)
+      end
+      
+      it "manufactures attributes associated with the projection relation" do
+        @projection.attributes.should == [@attribute].collect { |a| a.bind(@projection) }
+      end
+    end
+    
+    describe '==' do
+      before do
+        @another_relation = Table.new(:photos)
+        @another_attribute = @relation[:name]
+      end
+      
+      it "obtains if the relations and attributes are identical" do
+        Projection.new(@relation, @attribute).should == Projection.new(@relation, @attribute)
+        Projection.new(@relation, @attribute).should_not == Projection.new(@another_relation, @attribute)
+        Projection.new(@relation, @attribute).should_not == Projection.new(@relation, @another_attribute)
+      end
+    end
+  
+    describe '#to_sql' do
+      describe 'when given an attribute' do
+        it "manufactures sql with a limited select clause" do
+          Projection.new(@relation, @attribute).to_sql.should be_like("
+            SELECT `users`.`id`
+            FROM `users`
+          ")
+        end
+      end
+      
+      describe 'when given a relation' do
+        before do
+          @scalar_relation = Projection.new(@relation, @relation[:name])
+        end
+        
+        it "manufactures sql with scalar selects" do
+          Projection.new(@relation, @scalar_relation).to_sql.should be_like("
+            SELECT (SELECT `users`.`name` FROM `users`) FROM `users`
+          ")
+        end
+      end
+      
+      describe 'when given a string' do
+        it "passes the string through to the select clause" do
+          Projection.new(@relation, 'asdf').to_sql.should be_like("
+            SELECT asdf FROM `users`
+          ")
+        end
+      end
+    end
+    
+    describe Projection::Externalizable do
+      describe '#aggregation?' do
+        describe 'when the projections are attributes' do
+          it 'returns false' do
+            Projection.new(@relation, @attribute).should_not be_aggregation
+          end
+        end
+        
+        describe 'when the projections include an aggregation' do
+          it "obtains" do
+            Projection.new(@relation, @attribute.sum).should be_aggregation
+          end
+        end
+      end
+
+    end
+  end
+end
+\ No newline at end of file