1 files changed, 45 insertions, 0 deletions
diff --git a/spec/arel/algebra/unit/primitives/expression_spec.rb b/spec/arel/algebra/unit/primitives/expression_spec.rb
new file mode 100644
index 0000000000..768bb492a7
--- /dev/null
+++ b/spec/arel/algebra/unit/primitives/expression_spec.rb
@@ -0,0 +1,45 @@
+require File.join(File.dirname(__FILE__), '..', '..', '..', '..', 'spec_helper')
+
+module Arel
+  describe Expression do
+    before do
+      @relation = Table.new(:users)
+      @attribute = @relation[:id]
+    end
+
+    describe "#inspect" do
+      it "returns a simple, short inspect string" do
+        @attribute.count.inspect.should == "<Arel::Count <Attribute id>>"
+      end
+    end
+
+    describe Expression::Transformations do
+      before do
+        @expression = Count.new(@attribute)
+      end
+
+      describe '#bind' do
+        it "manufactures an attribute with a rebound relation and self as the ancestor" do
+          derived_relation = @relation.where(@relation[:id].eq(1))
+          @expression.bind(derived_relation).should == Count.new(@attribute.bind(derived_relation), nil, @expression)
+        end
+
+        it "returns self if the substituting to the same relation" do
+          @expression.bind(@relation).should == @expression
+        end
+      end
+
+      describe '#as' do
+        it "manufactures an aliased expression" do
+          @expression.as(:alias).should == Expression.new(@attribute, :alias, @expression)
+        end
+      end
+
+      describe '#to_attribute' do
+        it "manufactures an attribute with the expression as an ancestor" do
+          @expression.to_attribute(@relation).should == Attribute.new(@relation, @expression.alias, :ancestor => @expression)
+        end
+      end
+    end
+  end
+end