reorganizing tests

24 files changed, 2280 insertions, 0 deletions

diff --git a/spec/arel/engines/sql/integration/joins/with_adjacency_spec.rb b/spec/arel/engines/sql/integration/joins/with_adjacency_spec.rb
new file mode 100644
index 0000000000..50b0908441
--- /dev/null
+++ b/spec/arel/engines/sql/integration/joins/with_adjacency_spec.rb
@@ -0,0 +1,209 @@
+require File.join(File.dirname(__FILE__), '..', '..', '..', '..', '..', 'spec_helper')
+
+module Arel
+  describe Join do
+    before do
+      @relation1 = Table(:users)
+      @relation2 = @relation1.alias
+      @predicate = @relation1[:id].eq(@relation2[:id])
+    end
+
+    describe 'when joining a relation to itself' do
+      describe '#to_sql' do
+        it 'manufactures sql aliasing the table and attributes properly in the join predicate and the where clause' do
+          sql = @relation1.join(@relation2).on(@predicate).to_sql
+
+          adapter_is :mysql do
+            sql.should be_like(%Q{
+              SELECT `users`.`id`, `users`.`name`, `users_2`.`id`, `users_2`.`name`
+              FROM `users`
+                INNER JOIN `users` AS `users_2`
+                  ON `users`.`id` = `users_2`.`id`
+            })
+          end
+
+          adapter_is_not :mysql do
+            sql.should be_like(%Q{
+              SELECT "users"."id", "users"."name", "users_2"."id", "users_2"."name"
+              FROM "users"
+                INNER JOIN "users" AS "users_2"
+                  ON "users"."id" = "users_2"."id"
+            })
+          end
+        end
+
+        describe 'when joining with a where on the same relation' do
+          it 'manufactures sql aliasing the tables properly' do
+            sql = @relation1                                 \
+              .join(@relation2.where(@relation2[:id].eq(1))) \
+                .on(@predicate)                              \
+            .to_sql
+
+            adapter_is :mysql do
+              sql.should be_like(%Q{
+                SELECT `users`.`id`, `users`.`name`, `users_2`.`id`, `users_2`.`name`
+                FROM `users`
+                  INNER JOIN `users` AS `users_2`
+                    ON `users`.`id` = `users_2`.`id` AND `users_2`.`id` = 1
+              })
+            end
+
+            adapter_is_not :mysql do
+              sql.should be_like(%Q{
+                SELECT "users"."id", "users"."name", "users_2"."id", "users_2"."name"
+                FROM "users"
+                  INNER JOIN "users" AS "users_2"
+                    ON "users"."id" = "users_2"."id" AND "users_2"."id" = 1
+              })
+            end
+          end
+
+          describe 'when the where occurs before the alias' do
+            it 'manufactures sql aliasing the predicates properly' do
+              relation2 = @relation1.where(@relation1[:id].eq(1)).alias
+
+              sql = @relation1                            \
+                .join(relation2)                          \
+                  .on(relation2[:id].eq(@relation1[:id])) \
+              .to_sql
+
+              adapter_is :mysql do
+                sql.should be_like(%Q{
+                  SELECT `users`.`id`, `users`.`name`, `users_2`.`id`, `users_2`.`name`
+                  FROM `users`
+                  INNER JOIN `users` AS `users_2`
+                    ON `users_2`.`id` = `users`.`id` AND `users_2`.`id` = 1
+                })
+              end
+
+              adapter_is_not :mysql do
+                sql.should be_like(%Q{
+                  SELECT "users"."id", "users"."name", "users_2"."id", "users_2"."name"
+                  FROM "users"
+                  INNER JOIN "users" AS "users_2"
+                    ON "users_2"."id" = "users"."id" AND "users_2"."id" = 1
+                })
+              end
+            end
+          end
+        end
+
+        describe 'when joining the relation to itself multiple times' do
+          before do
+            @relation3 = @relation1.alias
+          end
+
+          describe 'when joining left-associatively' do
+            it 'manufactures sql aliasing the tables properly' do
+              sql = @relation1                                \
+                .join(@relation2                              \
+                  .join(@relation3)                           \
+                    .on(@relation2[:id].eq(@relation3[:id]))) \
+                  .on(@relation1[:id].eq(@relation2[:id]))                                 \
+              .to_sql
+
+              adapter_is :mysql do
+                sql.should be_like(%Q{
+                  SELECT `users`.`id`, `users`.`name`, `users_2`.`id`, `users_2`.`name`, `users_3`.`id`, `users_3`.`name`
+                  FROM `users`
+                    INNER JOIN `users` AS `users_2`
+                      ON `users`.`id` = `users_2`.`id`
+                    INNER JOIN `users` AS `users_3`
+                      ON `users_2`.`id` = `users_3`.`id`
+                })
+              end
+
+              adapter_is_not :mysql do
+                sql.should be_like(%Q{
+                  SELECT "users"."id", "users"."name", "users_2"."id", "users_2"."name", "users_3"."id", "users_3"."name"
+                  FROM "users"
+                    INNER JOIN "users" AS "users_2"
+                      ON "users"."id" = "users_2"."id"
+                    INNER JOIN "users" AS "users_3"
+                      ON "users_2"."id" = "users_3"."id"
+                })
+              end
+            end
+          end
+
+          describe 'when joining right-associatively' do
+            it 'manufactures sql aliasing the tables properly' do
+              sql = @relation1                                              \
+                .join(@relation2).on(@relation1[:id].eq(@relation2[:id]))   \
+                .join(@relation3).on(@relation2[:id].eq(@relation3[:id]))   \
+              .to_sql
+
+              adapter_is :mysql do
+                sql.should be_like(%Q{
+                  SELECT `users`.`id`, `users`.`name`, `users_2`.`id`, `users_2`.`name`, `users_3`.`id`, `users_3`.`name`
+                  FROM `users`
+                    INNER JOIN `users` AS `users_2`
+                      ON `users`.`id` = `users_2`.`id`
+                    INNER JOIN `users` AS `users_3`
+                      ON `users_2`.`id` = `users_3`.`id`
+                })
+              end
+
+              adapter_is_not :mysql do
+                sql.should be_like(%Q{
+                  SELECT "users"."id", "users"."name", "users_2"."id", "users_2"."name", "users_3"."id", "users_3"."name"
+                  FROM "users"
+                    INNER JOIN "users" AS "users_2"
+                      ON "users"."id" = "users_2"."id"
+                    INNER JOIN "users" AS "users_3"
+                      ON "users_2"."id" = "users_3"."id"
+                })
+              end
+            end
+          end
+        end
+      end
+
+      describe '[]' do
+        describe 'when given an attribute belonging to both sub-relations' do
+          it 'disambiguates the relation that serves as the ancestor to the attribute' do
+            @relation1          \
+              .join(@relation2) \
+                .on(@predicate) \
+            .should disambiguate_attributes(@relation1[:id], @relation2[:id])
+          end
+
+          describe 'when both relations are compound and only one is an alias' do
+            it 'disambiguates the relation that serves as the ancestor to the attribute' do
+              compound1 = @relation1.where(@predicate)
+              compound2 = compound1.alias
+              compound1           \
+                .join(compound2)  \
+                  .on(@predicate) \
+              .should disambiguate_attributes(compound1[:id], compound2[:id])
+            end
+          end
+
+          describe 'when the left relation is extremely compound' do
+            it 'disambiguates the relation that serves as the ancestor to the attribute' do
+              @relation1            \
+                .where(@predicate)  \
+                .where(@predicate)  \
+                .join(@relation2)   \
+                  .on(@predicate)   \
+              .should disambiguate_attributes(@relation1[:id], @relation2[:id])
+            end
+          end
+
+          describe 'when the right relation is extremely compound' do
+            it 'disambiguates the relation that serves as the ancestor to the attribute' do
+              @relation1                  \
+                .join(                    \
+                  @relation2              \
+                    .where(@predicate)    \
+                    .where(@predicate)    \
+                    .where(@predicate))   \
+                  .on(@predicate)         \
+              .should disambiguate_attributes(@relation1[:id], @relation2[:id])
+            end
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/spec/arel/engines/sql/integration/joins/with_aggregations_spec.rb b/spec/arel/engines/sql/integration/joins/with_aggregations_spec.rb
new file mode 100644
index 0000000000..709ae9f8d1
--- /dev/null
+++ b/spec/arel/engines/sql/integration/joins/with_aggregations_spec.rb
@@ -0,0 +1,167 @@
+require File.join(File.dirname(__FILE__), '..', '..', '..', '..', '..', 'spec_helper')
+
+module Arel
+  describe Join do
+    before do
+      @relation1 = Table(:users)
+      @relation2 = Table(:photos)
+      @predicate = @relation1[:id].eq(@relation2[:user_id])
+    end
+
+    describe 'when joining aggregated relations' do
+      before do
+        @aggregation = @relation2                                           \
+          .group(@relation2[:user_id])                                      \
+          .project(@relation2[:user_id], @relation2[:id].count.as(:cnt))    \
+      end
+
+      describe '#to_sql' do
+        # CLEANUP
+        it '' do
+          sql = @relation1.join(@relation2.take(3)).on(@predicate).to_sql
+
+          adapter_is :mysql do
+            sql.should be_like(%Q{
+              SELECT `users`.`id`, `users`.`name`, `photos_external`.`id`, `photos_external`.`user_id`, `photos_external`.`camera_id`
+              FROM `users`
+              INNER JOIN (SELECT `photos`.`id`, `photos`.`user_id`, `photos`.`camera_id` FROM `photos` LIMIT 3) AS `photos_external`
+                ON `users`.`id` = `photos_external`.`user_id`
+            })
+          end
+
+          adapter_is_not :mysql do
+            sql.should be_like(%Q{
+              SELECT "users"."id", "users"."name", "photos_external"."id", "photos_external"."user_id", "photos_external"."camera_id"
+              FROM "users"
+              INNER JOIN (SELECT "photos"."id", "photos"."user_id", "photos"."camera_id" FROM "photos" LIMIT 3) AS "photos_external"
+                ON "users"."id" = "photos_external"."user_id"
+            })
+          end
+        end
+
+        describe 'with the aggregation on the right' do
+          it 'manufactures sql joining the left table to a derived table' do
+            sql = @relation1.join(@aggregation).on(@predicate).to_sql
+
+            adapter_is :mysql do
+              sql.should be_like(%Q{
+                SELECT `users`.`id`, `users`.`name`, `photos_external`.`user_id`, `photos_external`.`cnt`
+                FROM `users`
+                  INNER JOIN (SELECT `photos`.`user_id`, COUNT(`photos`.`id`) AS `cnt` FROM `photos` GROUP BY `photos`.`user_id`) AS `photos_external`
+                    ON `users`.`id` = `photos_external`.`user_id`
+              })
+            end
+
+            adapter_is_not :mysql do
+              sql.should be_like(%Q{
+                SELECT "users"."id", "users"."name", "photos_external"."user_id", "photos_external"."cnt"
+                FROM "users"
+                  INNER JOIN (SELECT "photos"."user_id", COUNT("photos"."id") AS "cnt" FROM "photos" GROUP BY "photos"."user_id") AS "photos_external"
+                    ON "users"."id" = "photos_external"."user_id"
+              })
+            end
+          end
+        end
+
+        describe 'with the aggregation on the left' do
+          it 'manufactures sql joining the right table to a derived table' do
+            sql = @aggregation.join(@relation1).on(@predicate).to_sql
+
+            adapter_is :mysql do
+              sql.should be_like(%Q{
+                SELECT `photos_external`.`user_id`, `photos_external`.`cnt`, `users`.`id`, `users`.`name`
+                FROM (SELECT `photos`.`user_id`, COUNT(`photos`.`id`) AS `cnt` FROM `photos` GROUP BY `photos`.`user_id`) AS `photos_external`
+                  INNER JOIN `users`
+                    ON `users`.`id` = `photos_external`.`user_id`
+              })
+            end
+
+            adapter_is_not :mysql do
+              sql.should be_like(%Q{
+                SELECT "photos_external"."user_id", "photos_external"."cnt", "users"."id", "users"."name"
+                FROM (SELECT "photos"."user_id", COUNT("photos"."id") AS "cnt" FROM "photos" GROUP BY "photos"."user_id") AS "photos_external"
+                  INNER JOIN "users"
+                    ON "users"."id" = "photos_external"."user_id"
+              })
+            end
+          end
+        end
+
+        describe 'with the aggregation on both sides' do
+          it 'it properly aliases the aggregations' do
+            aggregation2 = @aggregation.alias
+            sql = @aggregation.join(aggregation2).on(aggregation2[:user_id].eq(@aggregation[:user_id])).to_sql
+
+            adapter_is :mysql do
+              sql.should be_like(%Q{
+                SELECT `photos_external`.`user_id`, `photos_external`.`cnt`, `photos_external_2`.`user_id`, `photos_external_2`.`cnt`
+                FROM (SELECT `photos`.`user_id`, COUNT(`photos`.`id`) AS `cnt` FROM `photos` GROUP BY  `photos`.`user_id`) AS `photos_external`
+                  INNER JOIN (SELECT `photos`.`user_id`, COUNT(`photos`.`id`) AS `cnt` FROM `photos` GROUP BY `photos`.`user_id`) AS `photos_external_2`
+                    ON `photos_external_2`.`user_id` = `photos_external`.`user_id`
+              })
+            end
+
+            adapter_is_not :mysql do
+              sql.should be_like(%Q{
+                SELECT "photos_external"."user_id", "photos_external"."cnt", "photos_external_2"."user_id", "photos_external_2"."cnt"
+                FROM (SELECT "photos"."user_id", COUNT("photos"."id") AS "cnt" FROM "photos" GROUP BY  "photos"."user_id") AS "photos_external"
+                  INNER JOIN (SELECT "photos"."user_id", COUNT("photos"."id") AS "cnt" FROM "photos" GROUP BY "photos"."user_id") AS "photos_external_2"
+                    ON "photos_external_2"."user_id" = "photos_external"."user_id"
+              })
+            end
+          end
+        end
+
+        describe 'when the aggration has a where' do
+          describe 'with the aggregation on the left' do
+            it "manufactures sql keeping wheres on the aggregation within the derived table" do
+              sql = @relation1.join(@aggregation.where(@aggregation[:user_id].eq(1))).on(@predicate).to_sql
+
+              adapter_is :mysql do
+                sql.should be_like(%Q{
+                  SELECT `users`.`id`, `users`.`name`, `photos_external`.`user_id`, `photos_external`.`cnt`
+                  FROM `users`
+                    INNER JOIN (SELECT `photos`.`user_id`, COUNT(`photos`.`id`) AS `cnt` FROM `photos` WHERE `photos`.`user_id` = 1 GROUP BY `photos`.`user_id`) AS `photos_external`
+                      ON `users`.`id` = `photos_external`.`user_id`
+                })
+              end
+
+              adapter_is_not :mysql do
+                sql.should be_like(%Q{
+                  SELECT "users"."id", "users"."name", "photos_external"."user_id", "photos_external"."cnt"
+                  FROM "users"
+                    INNER JOIN (SELECT "photos"."user_id", COUNT("photos"."id") AS "cnt" FROM "photos" WHERE "photos"."user_id" = 1 GROUP BY "photos"."user_id") AS "photos_external"
+                      ON "users"."id" = "photos_external"."user_id"
+                })
+              end
+            end
+          end
+
+          describe 'with the aggregation on the right' do
+            it "manufactures sql keeping wheres on the aggregation within the derived table" do
+              sql = @aggregation.where(@aggregation[:user_id].eq(1)).join(@relation1).on(@predicate).to_sql
+
+              adapter_is :mysql do
+                sql.should be_like(%Q{
+                  SELECT `photos_external`.`user_id`, `photos_external`.`cnt`, `users`.`id`, `users`.`name`
+                  FROM (SELECT `photos`.`user_id`, COUNT(`photos`.`id`) AS `cnt` FROM `photos` WHERE `photos`.`user_id` = 1 GROUP BY `photos`.`user_id`) AS `photos_external`
+                    INNER JOIN `users`
+                      ON `users`.`id` = `photos_external`.`user_id`
+                })
+              end
+
+              adapter_is_not :mysql do
+                sql.should be_like(%Q{
+                  SELECT "photos_external"."user_id", "photos_external"."cnt", "users"."id", "users"."name"
+                  FROM (SELECT "photos"."user_id", COUNT("photos"."id") AS "cnt" FROM "photos" WHERE "photos"."user_id" = 1 GROUP BY "photos"."user_id") AS "photos_external"
+                    INNER JOIN "users"
+                      ON "users"."id" = "photos_external"."user_id"
+                })
+              end
+            end
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/spec/arel/engines/sql/integration/joins/with_compounds_spec.rb b/spec/arel/engines/sql/integration/joins/with_compounds_spec.rb
new file mode 100644
index 0000000000..4bceef4975
--- /dev/null
+++ b/spec/arel/engines/sql/integration/joins/with_compounds_spec.rb
@@ -0,0 +1,107 @@
+require File.join(File.dirname(__FILE__), '..', '..', '..', '..', '..', 'spec_helper')
+
+module Arel
+  describe Join do
+    before do
+      @relation1 = Table(:users)
+      @relation2 = Table(:photos)
+      @predicate = @relation1[:id].eq(@relation2[:user_id])
+    end
+
+    describe '#to_sql' do
+      describe 'when the join contains a where' do
+        describe 'and the where is given a string' do
+          it 'does not escape the string' do
+            sql = @relation1                    \
+              .join(@relation2.where("asdf"))   \
+                .on(@predicate)                 \
+            .to_sql
+
+            adapter_is :mysql do
+              sql.should be_like(%Q{
+                SELECT `users`.`id`, `users`.`name`, `photos`.`id`, `photos`.`user_id`, `photos`.`camera_id`
+                FROM `users`
+                INNER JOIN `photos`
+                  ON `users`.`id` = `photos`.`user_id` AND asdf
+              })
+            end
+
+            adapter_is_not :mysql do
+              sql.should be_like(%Q{
+                SELECT "users"."id", "users"."name", "photos"."id", "photos"."user_id", "photos"."camera_id"
+                FROM "users"
+                INNER JOIN "photos"
+                  ON "users"."id" = "photos"."user_id" AND asdf
+              })
+            end
+          end
+        end
+      end
+
+      describe 'when a compound contains a join' do
+        describe 'and the compound is a where' do
+          it 'manufactures sql disambiguating the tables' do
+            sql = @relation1                  \
+              .where(@relation1[:id].eq(1))   \
+              .join(@relation2)               \
+                .on(@predicate)               \
+              .where(@relation1[:id].eq(1))   \
+            .to_sql
+
+            adapter_is :mysql do
+              sql.should be_like(%Q{
+                SELECT `users`.`id`, `users`.`name`, `photos`.`id`, `photos`.`user_id`, `photos`.`camera_id`
+                FROM `users`
+                INNER JOIN `photos`
+                  ON `users`.`id` = `photos`.`user_id`
+                WHERE `users`.`id` = 1
+                  AND `users`.`id` = 1
+              })
+            end
+
+            adapter_is_not :mysql do
+              sql.should be_like(%Q{
+                SELECT "users"."id", "users"."name", "photos"."id", "photos"."user_id", "photos"."camera_id"
+                FROM "users"
+                INNER JOIN "photos"
+                  ON "users"."id" = "photos"."user_id"
+                WHERE "users"."id" = 1
+                  AND "users"."id" = 1
+              })
+            end
+          end
+        end
+
+        describe 'and the compound is a group' do
+          it 'manufactures sql disambiguating the tables' do
+            sql = @relation1          \
+              .join(@relation2)       \
+                .on(@predicate)       \
+              .group(@relation1[:id]) \
+            .to_sql
+
+            adapter_is :mysql do
+              sql.should be_like(%Q{
+                SELECT `users`.`id`, `users`.`name`, `photos`.`id`, `photos`.`user_id`, `photos`.`camera_id`
+                FROM `users`
+                INNER JOIN `photos`
+                  ON `users`.`id` = `photos`.`user_id`
+                GROUP BY `users`.`id`
+              })
+            end
+
+            adapter_is_not :mysql do
+              sql.should be_like(%Q{
+                SELECT "users"."id", "users"."name", "photos"."id", "photos"."user_id", "photos"."camera_id"
+                FROM "users"
+                INNER JOIN "photos"
+                  ON "users"."id" = "photos"."user_id"
+                GROUP BY "users"."id"
+              })
+            end
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/spec/arel/engines/sql/unit/predicates/binary_spec.rb b/spec/arel/engines/sql/unit/predicates/binary_spec.rb
new file mode 100644
index 0000000000..03574225c2
--- /dev/null
+++ b/spec/arel/engines/sql/unit/predicates/binary_spec.rb
@@ -0,0 +1,125 @@
+require File.join(File.dirname(__FILE__), '..', '..', '..', '..', '..', 'spec_helper')
+
+module Arel
+  describe Binary do
+    before do
+      @relation = Table.new(:users)
+      @attribute1 = @relation[:id]
+      @attribute2 = @relation[:name]
+      class ConcreteBinary < Binary
+        def predicate_sql
+          "<=>"
+        end
+      end
+    end
+
+    describe "with compound predicates" do
+      before do
+        @operand1 = ConcreteBinary.new(@attribute1, 1)
+        @operand2 = ConcreteBinary.new(@attribute2, "name")
+      end
+
+      describe Or do
+        describe "#to_sql" do
+          it "manufactures sql with an OR operation" do
+            sql = Or.new(@operand1, @operand2).to_sql
+
+            adapter_is :mysql do
+              sql.should be_like(%Q{(`users`.`id` <=> 1 OR `users`.`name` <=> 'name')})
+            end
+
+            adapter_is_not :mysql do
+              sql.should be_like(%Q{("users"."id" <=> 1 OR "users"."name" <=> 'name')})
+            end
+          end
+        end
+      end
+
+      describe And do
+        describe "#to_sql" do
+          it "manufactures sql with an AND operation" do
+            sql = And.new(@operand1, @operand2).to_sql
+
+            adapter_is :mysql do
+              sql.should be_like(%Q{(`users`.`id` <=> 1 AND `users`.`name` <=> 'name')})
+            end
+
+            adapter_is_not :mysql do
+              sql.should be_like(%Q{("users"."id" <=> 1 AND "users"."name" <=> 'name')})
+            end
+          end
+        end
+      end
+    end
+
+    describe '#to_sql' do
+      describe 'when relating two attributes' do
+        it 'manufactures sql with a binary operation' do
+          sql = ConcreteBinary.new(@attribute1, @attribute2).to_sql
+
+          adapter_is :mysql do
+            sql.should be_like(%Q{`users`.`id` <=> `users`.`name`})
+          end
+
+          adapter_is_not :mysql do
+            sql.should be_like(%Q{"users"."id" <=> "users"."name"})
+          end
+        end
+      end
+
+      describe 'when relating an attribute and a value' do
+        before do
+          @value = "1-asdf"
+        end
+
+        describe 'when relating to an integer attribute' do
+          it 'formats values as integers' do
+            sql = ConcreteBinary.new(@attribute1, @value).to_sql
+
+            adapter_is :mysql do
+              sql.should be_like(%Q{`users`.`id` <=> 1})
+            end
+
+            adapter_is_not :mysql do
+              sql.should be_like(%Q{"users"."id" <=> 1})
+            end
+          end
+        end
+
+        describe 'when relating to a string attribute' do
+          it 'formats values as strings' do
+            sql = ConcreteBinary.new(@attribute2, @value).to_sql
+
+            adapter_is :mysql do
+              sql.should be_like(%Q{`users`.`name` <=> '1-asdf'})
+            end
+
+            adapter_is_not :mysql do
+              sql.should be_like(%Q{"users"."name" <=> '1-asdf'})
+            end
+          end
+        end
+      end
+    end
+
+    describe '#bind' do
+      before do
+        @another_relation = @relation.alias
+      end
+
+      describe 'when both operands are attributes' do
+        it "manufactures an expression with the attributes bound to the relation" do
+          ConcreteBinary.new(@attribute1, @attribute2).bind(@another_relation). \
+            should == ConcreteBinary.new(@another_relation[@attribute1], @another_relation[@attribute2])
+        end
+      end
+
+      describe 'when an operand is a value' do
+        it "manufactures an expression with unmodified values" do
+          ConcreteBinary.new(@attribute1, "asdf").bind(@another_relation). \
+            should == ConcreteBinary.new(@attribute1.find_correlate_in(@another_relation), "asdf".find_correlate_in(@another_relation))
+        end
+      end
+    end
+  end
+end
\ No newline at end of file
diff --git a/spec/arel/engines/sql/unit/predicates/equality_spec.rb b/spec/arel/engines/sql/unit/predicates/equality_spec.rb
new file mode 100644
index 0000000000..2ab79d7028
--- /dev/null
+++ b/spec/arel/engines/sql/unit/predicates/equality_spec.rb
@@ -0,0 +1,61 @@
+require File.join(File.dirname(__FILE__), '..', '..', '..', '..', '..', 'spec_helper')
+
+module Arel
+  describe Equality do
+    before do
+      @relation1 = Table.new(:users)
+      @relation2 = Table.new(:photos)
+      @attribute1 = @relation1[:id]
+      @attribute2 = @relation2[:user_id]
+    end
+
+    describe '==' do
+      it "obtains if attribute1 and attribute2 are identical" do
+        Equality.new(@attribute1, @attribute2).should == Equality.new(@attribute1, @attribute2)
+        Equality.new(@attribute1, @attribute2).should_not == Equality.new(@attribute1, @attribute1)
+      end
+
+      it "obtains if the concrete type of the predicates are identical" do
+        Equality.new(@attribute1, @attribute2).should_not == Binary.new(@attribute1, @attribute2)
+      end
+
+      it "is commutative on the attributes" do
+        Equality.new(@attribute1, @attribute2).should == Equality.new(@attribute2, @attribute1)
+      end
+    end
+
+    describe '#to_sql' do
+      describe 'when relating to a non-nil value' do
+        it "manufactures an equality predicate" do
+          sql = Equality.new(@attribute1, @attribute2).to_sql
+
+          adapter_is :mysql do
+            sql.should be_like(%Q{`users`.`id` = `photos`.`user_id`})
+          end
+
+          adapter_is_not :mysql do
+            sql.should be_like(%Q{"users"."id" = "photos"."user_id"})
+          end
+        end
+      end
+
+      describe 'when relation to a nil value' do
+        before do
+          @nil = nil
+        end
+
+        it "manufactures an is null predicate" do
+          sql = Equality.new(@attribute1, @nil).to_sql
+
+          adapter_is :mysql do
+            sql.should be_like(%Q{`users`.`id` IS NULL})
+          end
+
+          adapter_is_not :mysql do
+            sql.should be_like(%Q{"users"."id" IS NULL})
+          end
+        end
+      end
+    end
+  end
+end
\ No newline at end of file
diff --git a/spec/arel/engines/sql/unit/predicates/in_spec.rb b/spec/arel/engines/sql/unit/predicates/in_spec.rb
new file mode 100644
index 0000000000..d977937e4e
--- /dev/null
+++ b/spec/arel/engines/sql/unit/predicates/in_spec.rb
@@ -0,0 +1,86 @@
+require File.join(File.dirname(__FILE__), '..', '..', '..', '..', '..', 'spec_helper')
+
+module Arel
+  describe In do
+    before do
+      @relation = Table.new(:users)
+      @attribute = @relation[:id]
+    end
+
+    describe '#to_sql' do
+      describe 'when relating to an array' do
+        describe 'when the array\'s elements are the same type as the attribute' do
+          before do
+            @array = [1, 2, 3]
+          end
+
+          it 'manufactures sql with a comma separated list' do
+            sql = In.new(@attribute, @array).to_sql
+
+            adapter_is :mysql do
+              sql.should be_like(%Q{`users`.`id` IN (1, 2, 3)})
+            end
+
+            adapter_is_not :mysql do
+              sql.should be_like(%Q{"users"."id" IN (1, 2, 3)})
+            end
+          end
+        end
+
+        describe 'when the array\'s elements are not same type as the attribute' do
+          before do
+            @array = ['1-asdf', 2, 3]
+          end
+
+          it 'formats values in the array as the type of the attribute' do
+            sql = In.new(@attribute, @array).to_sql
+
+            adapter_is :mysql do
+              sql.should be_like(%Q{`users`.`id` IN (1, 2, 3)})
+            end
+
+            adapter_is_not :mysql do
+              sql.should be_like(%Q{"users"."id" IN (1, 2, 3)})
+            end
+          end
+        end
+      end
+
+      describe 'when relating to a range' do
+        before do
+          @range = 1..2
+        end
+
+        it 'manufactures sql with a between' do
+          sql = In.new(@attribute, @range).to_sql
+
+          adapter_is :mysql do
+            sql.should be_like(%Q{`users`.`id` BETWEEN 1 AND 2})
+          end
+
+          adapter_is_not :mysql do
+            sql.should be_like(%Q{"users"."id" BETWEEN 1 AND 2})
+          end
+        end
+      end
+
+      describe 'when relating to a relation' do
+        it 'manufactures sql with a subselect' do
+          sql = In.new(@attribute, @relation).to_sql
+
+          adapter_is :mysql do
+            sql.should be_like(%Q{
+              `users`.`id` IN (SELECT `users`.`id`, `users`.`name` FROM `users`)
+            })
+          end
+
+          adapter_is_not :mysql do
+            sql.should be_like(%Q{
+              "users"."id" IN (SELECT "users"."id", "users"."name" FROM "users")
+            })
+          end
+        end
+      end
+    end
+  end
+end
\ No newline at end of file
diff --git a/spec/arel/engines/sql/unit/primitives/attribute_spec.rb b/spec/arel/engines/sql/unit/primitives/attribute_spec.rb
new file mode 100644
index 0000000000..f37cd14370
--- /dev/null
+++ b/spec/arel/engines/sql/unit/primitives/attribute_spec.rb
@@ -0,0 +1,171 @@
+require File.join(File.dirname(__FILE__), '..', '..', '..', '..', '..', 'spec_helper')
+
+module Arel
+  describe Attribute do
+    before do
+      @relation = Table.new(:users)
+      @attribute = @relation[:id]
+    end
+
+    describe Attribute::Transformations do
+      describe '#as' do
+        it "manufactures an aliased attributed" do
+          @attribute.as(:alias).should == Attribute.new(@relation, @attribute.name, :alias => :alias, :ancestor => @attribute)
+        end
+      end
+
+      describe '#bind' do
+        it "manufactures an attribute with the relation bound and self as an ancestor" do
+          derived_relation = @relation.where(@relation[:id].eq(1))
+          @attribute.bind(derived_relation).should == Attribute.new(derived_relation, @attribute.name, :ancestor => @attribute)
+        end
+
+        it "returns self if the substituting to the same relation" do
+          @attribute.bind(@relation).should == @attribute
+        end
+      end
+
+      describe '#to_attribute' do
+        it "returns self" do
+          @attribute.to_attribute.should == @attribute
+        end
+      end
+    end
+
+    describe '#column' do
+      it "returns the corresponding column in the relation" do
+        @attribute.column.should == @relation.column_for(@attribute)
+      end
+    end
+
+    describe '#engine' do
+      it "delegates to its relation" do
+        Attribute.new(@relation, :id).engine.should == @relation.engine
+      end
+    end
+
+    describe Attribute::Congruence do
+      describe '/' do
+        before do
+          @aliased_relation = @relation.alias
+          @doubly_aliased_relation = @aliased_relation.alias
+        end
+
+        describe 'when dividing two unrelated attributes' do
+          it "returns 0.0" do
+            (@relation[:id] / @relation[:name]).should == 0.0
+          end
+        end
+
+        describe 'when dividing two matching attributes' do
+          it 'returns a the highest score for the most similar attributes' do
+            (@aliased_relation[:id] / @relation[:id]) \
+              .should == (@aliased_relation[:id] / @relation[:id])
+            (@aliased_relation[:id] / @relation[:id]) \
+              .should < (@aliased_relation[:id] / @aliased_relation[:id])
+          end
+        end
+      end
+    end
+
+    describe '#to_sql' do
+      describe 'for a simple attribute' do
+        it "manufactures sql with an alias" do
+          sql = @attribute.to_sql
+
+          adapter_is :mysql do
+            sql.should be_like(%Q{`users`.`id`})
+          end
+
+          adapter_is_not :mysql do
+            sql.should be_like(%Q{"users"."id"})
+          end
+        end
+      end
+    end
+
+    describe Attribute::Predications do
+      before do
+        @attribute = Attribute.new(@relation, :name)
+      end
+
+      describe '#eq' do
+        it "manufactures an equality predicate" do
+          @attribute.eq('name').should == Equality.new(@attribute, 'name')
+        end
+      end
+
+      describe '#lt' do
+        it "manufactures a less-than predicate" do
+          @attribute.lt(10).should == LessThan.new(@attribute, 10)
+        end
+      end
+
+      describe '#lteq' do
+        it "manufactures a less-than or equal-to predicate" do
+          @attribute.lteq(10).should == LessThanOrEqualTo.new(@attribute, 10)
+        end
+      end
+
+      describe '#gt' do
+        it "manufactures a greater-than predicate" do
+          @attribute.gt(10).should == GreaterThan.new(@attribute, 10)
+        end
+      end
+
+      describe '#gteq' do
+        it "manufactures a greater-than or equal-to predicate" do
+          @attribute.gteq(10).should == GreaterThanOrEqualTo.new(@attribute, 10)
+        end
+      end
+
+      describe '#matches' do
+        it "manufactures a match predicate" do
+          @attribute.matches(/.*/).should == Match.new(@attribute, /.*/)
+        end
+      end
+
+      describe '#in' do
+        it "manufactures an in predicate" do
+          @attribute.in(1..30).should == In.new(@attribute, (1..30))
+        end
+      end
+    end
+
+    describe Attribute::Expressions do
+      before do
+        @attribute = Attribute.new(@relation, :name)
+      end
+
+      describe '#count' do
+        it "manufactures a count Expression" do
+          @attribute.count.should == Count.new(@attribute)
+        end
+      end
+
+      describe '#sum' do
+        it "manufactures a sum Expression" do
+          @attribute.sum.should == Sum.new(@attribute)
+        end
+      end
+
+      describe '#maximum' do
+        it "manufactures a maximum Expression" do
+          @attribute.maximum.should == Maximum.new(@attribute)
+        end
+      end
+
+      describe '#minimum' do
+        it "manufactures a minimum Expression" do
+          @attribute.minimum.should == Minimum.new(@attribute)
+        end
+      end
+
+      describe '#average' do
+        it "manufactures an average Expression" do
+          @attribute.average.should == Average.new(@attribute)
+        end
+      end
+    end
+  end
+end
\ No newline at end of file
diff --git a/spec/arel/engines/sql/unit/primitives/expression_spec.rb b/spec/arel/engines/sql/unit/primitives/expression_spec.rb
new file mode 100644
index 0000000000..0869d9e403
--- /dev/null
+++ b/spec/arel/engines/sql/unit/primitives/expression_spec.rb
@@ -0,0 +1,53 @@
+require File.join(File.dirname(__FILE__), '..', '..', '..', '..', '..', 'spec_helper')
+
+module Arel
+  describe Expression do
+    before do
+      @relation = Table.new(:users)
+      @attribute = @relation[:id]
+    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.should == Attribute.new(@expression.relation, @expression.alias, :ancestor => @expression)
+        end
+      end
+    end
+
+    describe '#to_sql' do
+      it "manufactures sql with the expression and alias" do
+        sql = Count.new(@attribute, :alias).to_sql
+
+        adapter_is :mysql do
+          sql.should be_like(%Q{COUNT(`users`.`id`) AS `alias`})
+        end
+
+        adapter_is_not :mysql do
+          sql.should be_like(%Q{COUNT("users"."id") AS "alias"})
+        end
+      end
+    end
+  end
+end
diff --git a/spec/arel/engines/sql/unit/primitives/value_spec.rb b/spec/arel/engines/sql/unit/primitives/value_spec.rb
new file mode 100644
index 0000000000..f76323f32b
--- /dev/null
+++ b/spec/arel/engines/sql/unit/primitives/value_spec.rb
@@ -0,0 +1,28 @@
+require File.join(File.dirname(__FILE__), '..', '..', '..', '..', '..', 'spec_helper')
+
+module Arel
+  describe Value do
+    before do
+      @relation = Table.new(:users)
+    end
+
+    describe '#to_sql' do
+      it "appropriately quotes the value" do
+        Value.new(1, @relation).to_sql.should be_like('1')
+        Value.new('asdf', @relation).to_sql.should be_like("'asdf'")
+      end
+    end
+
+    describe '#format' do
+      it "returns the sql of the provided object" do
+        Value.new(1, @relation).format(@relation[:id]).should == @relation[:id].to_sql
+      end
+    end
+
+    describe '#bind' do
+      it "manufactures a new value whose relation is the provided relation" do
+        Value.new(1, @relation).bind(another_relation = Table.new(:photos)).should == Value.new(1, another_relation)
+      end
+    end
+  end
+end
diff --git a/spec/arel/engines/sql/unit/relations/alias_spec.rb b/spec/arel/engines/sql/unit/relations/alias_spec.rb
new file mode 100644
index 0000000000..83b9113f6d
--- /dev/null
+++ b/spec/arel/engines/sql/unit/relations/alias_spec.rb
@@ -0,0 +1,50 @@
+require File.join(File.dirname(__FILE__), '..', '..', '..', '..', '..', 'spec_helper')
+
+module Arel
+  describe Alias do
+    before do
+      @relation = Table.new(:users)
+    end
+
+    describe '==' do
+      it "obtains if the objects are the same" do
+        Alias.new(@relation).should_not == Alias.new(@relation)
+        (aliaz = Alias.new(@relation)).should == aliaz
+      end
+    end
+
+    describe '#to_sql' do
+      describe 'when there is no ambiguity' do
+        it 'does not alias table names anywhere a table name can appear' do
+          sql = @relation                 \
+            .where(@relation[:id].eq(1))  \
+            .order(@relation[:id])        \
+            .project(@relation[:id])      \
+            .group(@relation[:id])        \
+            .alias                        \
+          .to_sql
+
+          adapter_is :mysql do
+            sql.should be_like(%Q{
+              SELECT `users`.`id`
+              FROM `users`
+              WHERE `users`.`id` = 1
+              GROUP BY `users`.`id`
+              ORDER BY `users`.`id` ASC
+            })
+          end
+
+          adapter_is_not :mysql do
+            sql.should be_like(%Q{
+              SELECT "users"."id"
+              FROM "users"
+              WHERE "users"."id" = 1
+              GROUP BY "users"."id"
+              ORDER BY "users"."id" ASC
+            })
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/spec/arel/engines/sql/unit/relations/array_spec.rb b/spec/arel/engines/sql/unit/relations/array_spec.rb
new file mode 100644
index 0000000000..8d40858c5f
--- /dev/null
+++ b/spec/arel/engines/sql/unit/relations/array_spec.rb
@@ -0,0 +1,87 @@
+require File.join(File.dirname(__FILE__), '..', '..', '..', '..', '..', 'spec_helper')
+
+module Arel
+  describe Array do
+    before do
+      @relation = Array.new([
+        [1, 'duck' ],
+        [2, 'duck' ],
+        [3, 'goose']
+      ], [:id, :name])
+    end
+
+    describe '#attributes' do
+      it 'manufactures attributes corresponding to the names given on construction' do
+        @relation.attributes.should == [
+          Attribute.new(@relation, :id),
+          Attribute.new(@relation, :name)
+        ]
+      end
+    end
+
+    describe '#call' do
+      it "manufactures an array of hashes of attributes to values" do
+        @relation.call.should == [
+          { @relation[:id] => 1, @relation[:name] => 'duck'  },
+          { @relation[:id] => 2, @relation[:name] => 'duck'  },
+          { @relation[:id] => 3, @relation[:name] => 'goose' }
+        ]
+      end
+      
+      describe 'where' do
+        it 'filters the relation with the provided predicate' do
+          @relation.where(@relation[:id].lt(3)).call.should == [
+            { @relation[:id] => 1, @relation[:name] => 'duck' },
+            { @relation[:id] => 2, @relation[:name] => 'duck' }
+          ]
+        end
+      end
+      
+      describe 'group' do
+        it 'sorts the relation with the provided ordering' do
+        end
+      end
+      
+      describe 'order' do
+        it 'sorts the relation with the provided ordering' do
+          @relation.order(@relation[:id].desc).call.should == [
+            { @relation[:id] => 3, @relation[:name] => 'goose' },
+            { @relation[:id] => 2, @relation[:name] => 'duck'  },
+            { @relation[:id] => 1, @relation[:name] => 'duck'  }
+          ]
+        end
+      end
+      
+      describe 'project' do
+        it 'projects' do
+          @relation.project(@relation[:id]).call.should == [
+            { @relation[:id] => 1 },
+            { @relation[:id] => 2 },
+            { @relation[:id] => 3 }
+          ]
+        end
+      end
+      
+      describe 'skip' do
+        it 'slices' do
+          @relation.skip(1).call.should == [
+            { @relation[:id] => 2, @relation[:name] => 'duck'  },
+            { @relation[:id] => 3, @relation[:name] => 'goose' }
+          ]
+        end
+      end
+      
+      describe 'take' do
+        it 'dices' do
+          @relation.take(2).call.should == [
+            { @relation[:id] => 1, @relation[:name] => 'duck' },
+            { @relation[:id] => 2, @relation[:name] => 'duck' }
+          ]
+        end
+      end
+      
+      describe 'join' do
+      end
+    end
+  end
+end
\ No newline at end of file
diff --git a/spec/arel/engines/sql/unit/relations/delete_spec.rb b/spec/arel/engines/sql/unit/relations/delete_spec.rb
new file mode 100644
index 0000000000..7a5e2b0088
--- /dev/null
+++ b/spec/arel/engines/sql/unit/relations/delete_spec.rb
@@ -0,0 +1,63 @@
+require File.join(File.dirname(__FILE__), '..', '..', '..', '..', '..', 'spec_helper')
+
+module Arel
+  describe Deletion do
+    before do
+      @relation = Table.new(:users)
+    end
+
+    describe '#to_sql' do
+      it 'manufactures sql deleting a table relation' do
+        sql = Deletion.new(@relation).to_sql
+
+        adapter_is :mysql do
+          sql.should be_like(%Q{DELETE FROM `users`})
+        end
+
+        adapter_is_not :mysql do
+          sql.should be_like(%Q{DELETE FROM "users"})
+        end
+      end
+
+      it 'manufactures sql deleting a where relation' do
+        sql = Deletion.new(@relation.where(@relation[:id].eq(1))).to_sql
+
+        adapter_is :mysql do
+          sql.should be_like(%Q{
+            DELETE
+            FROM `users`
+            WHERE `users`.`id` = 1
+          })
+        end
+
+        adapter_is_not :mysql do
+          sql.should be_like(%Q{
+            DELETE
+            FROM "users"
+            WHERE "users"."id" = 1
+          })
+        end
+      end
+
+      it "manufactures sql deleting a ranged relation" do
+        sql = Deletion.new(@relation.take(1)).to_sql
+
+        adapter_is :mysql do
+          sql.should be_like(%Q{
+            DELETE
+            FROM `users`
+            LIMIT 1
+          })
+        end
+
+        adapter_is_not :mysql do
+          sql.should be_like(%Q{
+            DELETE
+            FROM "users"
+            LIMIT 1
+          })
+        end
+      end
+    end
+  end
+end
diff --git a/spec/arel/engines/sql/unit/relations/group_spec.rb b/spec/arel/engines/sql/unit/relations/group_spec.rb
new file mode 100644
index 0000000000..b7279a23d9
--- /dev/null
+++ b/spec/arel/engines/sql/unit/relations/group_spec.rb
@@ -0,0 +1,56 @@
+require File.join(File.dirname(__FILE__), '..', '..', '..', '..', '..', 'spec_helper')
+
+module Arel
+  describe Group do
+    before do
+      @relation = Table.new(:users)
+      @attribute = @relation[:id]
+    end
+
+    describe '#to_sql' do
+      describe 'when given a predicate' do
+        it "manufactures sql with where clause conditions" do
+          sql = Group.new(@relation, @attribute).to_sql
+
+          adapter_is :mysql do
+            sql.should be_like(%Q{
+              SELECT `users`.`id`, `users`.`name`
+              FROM `users`
+              GROUP BY `users`.`id`
+            })
+          end
+
+          adapter_is_not :mysql do
+            sql.should be_like(%Q{
+              SELECT "users"."id", "users"."name"
+              FROM "users"
+              GROUP BY "users"."id"
+            })
+          end
+        end
+      end
+
+      describe 'when given a string' do
+        it "passes the string through to the where clause" do
+          sql = Group.new(@relation, 'asdf').to_sql
+
+          adapter_is :mysql do
+            sql.should be_like(%Q{
+              SELECT `users`.`id`, `users`.`name`
+              FROM `users`
+              GROUP BY asdf
+            })
+          end
+
+          adapter_is_not :mysql do
+            sql.should be_like(%Q{
+              SELECT "users"."id", "users"."name"
+              FROM "users"
+              GROUP BY asdf
+            })
+          end
+        end
+      end
+    end
+  end
+end
\ No newline at end of file
diff --git a/spec/arel/engines/sql/unit/relations/insert_spec.rb b/spec/arel/engines/sql/unit/relations/insert_spec.rb
new file mode 100644
index 0000000000..dd1995cced
--- /dev/null
+++ b/spec/arel/engines/sql/unit/relations/insert_spec.rb
@@ -0,0 +1,91 @@
+require File.join(File.dirname(__FILE__), '..', '..', '..', '..', '..', 'spec_helper')
+
+module Arel
+  describe Insert do
+    before do
+      @relation = Table.new(:users)
+    end
+
+    describe '#to_sql' do
+      it 'manufactures sql inserting data when given multiple rows' do
+        pending 'it should insert multiple rows' do
+          @insertion = Insert.new(@relation, [@relation[:name] => "nick", @relation[:name] => "bryan"])
+
+          @insertion.to_sql.should be_like("
+            INSERT
+            INTO `users`
+            (`name`) VALUES ('nick'), ('bryan')
+          ")
+        end
+      end
+
+      it 'manufactures sql inserting data when given multiple values' do
+        @insertion = Insert.new(@relation, @relation[:id] => "1", @relation[:name] => "nick")
+
+        adapter_is :mysql do
+          @insertion.to_sql.should be_like(%Q{
+            INSERT
+            INTO `users`
+            (`id`, `name`) VALUES (1, 'nick')
+          })
+        end
+
+        adapter_is_not :mysql do
+          @insertion.to_sql.should be_like(%Q{
+            INSERT
+            INTO "users"
+            ("id", "name") VALUES (1, 'nick')
+          })
+        end
+      end
+
+      describe 'when given values whose types correspond to the types of the attributes' do
+        before do
+          @insertion = Insert.new(@relation, @relation[:name] => "nick")
+        end
+
+        it 'manufactures sql inserting data' do
+          adapter_is :mysql do
+            @insertion.to_sql.should be_like(%Q{
+              INSERT
+              INTO `users`
+              (`name`) VALUES ('nick')
+            })
+          end
+
+          adapter_is_not :mysql do
+            @insertion.to_sql.should be_like(%Q{
+              INSERT
+              INTO "users"
+              ("name") VALUES ('nick')
+            })
+          end
+        end
+      end
+
+      describe 'when given values whose types differ from from the types of the attributes' do
+        before do
+          @insertion = Insert.new(@relation, @relation[:id] => '1-asdf')
+        end
+
+        it 'manufactures sql inserting data' do
+          adapter_is :mysql do
+            @insertion.to_sql.should be_like(%Q{
+              INSERT
+              INTO `users`
+              (`id`) VALUES (1)
+            })
+          end
+
+          adapter_is_not :mysql do
+            @insertion.to_sql.should be_like(%Q{
+              INSERT
+              INTO "users"
+              ("id") VALUES (1)
+            })
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/spec/arel/engines/sql/unit/relations/join_spec.rb b/spec/arel/engines/sql/unit/relations/join_spec.rb
new file mode 100644
index 0000000000..ea17f8106f
--- /dev/null
+++ b/spec/arel/engines/sql/unit/relations/join_spec.rb
@@ -0,0 +1,78 @@
+require File.join(File.dirname(__FILE__), '..', '..', '..', '..', '..', 'spec_helper')
+
+module Arel
+  describe Join do
+    before do
+      @relation1 = Table.new(:users)
+      @relation2 = Table.new(:photos)
+      @predicate = @relation1[:id].eq(@relation2[:user_id])
+    end
+
+    describe 'hashing' do
+      it 'implements hash equality' do
+        InnerJoin.new(@relation1, @relation2, @predicate) \
+          .should hash_the_same_as(InnerJoin.new(@relation1, @relation2, @predicate))
+      end
+    end
+
+    describe '#engine' do
+      it "delegates to a relation's engine" do
+        InnerJoin.new(@relation1, @relation2, @predicate).engine.should == @relation1.engine
+      end
+    end
+
+    describe '#attributes' do
+      it 'combines the attributes of the two relations' do
+        join = InnerJoin.new(@relation1, @relation2, @predicate)
+        join.attributes.should ==
+          (@relation1.attributes + @relation2.attributes).collect { |a| a.bind(join) }
+      end
+    end
+
+    describe '#to_sql' do
+      describe 'when joining with another relation' do
+        it 'manufactures sql joining the two tables on the predicate' do
+          sql = InnerJoin.new(@relation1, @relation2, @predicate).to_sql
+
+          adapter_is :mysql do
+            sql.should be_like(%Q{
+              SELECT `users`.`id`, `users`.`name`, `photos`.`id`, `photos`.`user_id`, `photos`.`camera_id`
+              FROM `users`
+                INNER JOIN `photos` ON `users`.`id` = `photos`.`user_id`
+            })
+          end
+
+          adapter_is_not :mysql do
+            sql.should be_like(%Q{
+              SELECT "users"."id", "users"."name", "photos"."id", "photos"."user_id", "photos"."camera_id"
+              FROM "users"
+                INNER JOIN "photos" ON "users"."id" = "photos"."user_id"
+            })
+          end
+        end
+      end
+
+      describe 'when joining with a string' do
+        it "passes the string through to the where clause" do
+          sql = StringJoin.new(@relation1, "INNER JOIN asdf ON fdsa").to_sql
+
+          adapter_is :mysql do
+            sql.should be_like(%Q{
+              SELECT `users`.`id`, `users`.`name`
+              FROM `users`
+                INNER JOIN asdf ON fdsa
+            })
+          end
+
+          adapter_is_not :mysql do
+            sql.should be_like(%Q{
+              SELECT "users"."id", "users"."name"
+              FROM "users"
+                INNER JOIN asdf ON fdsa
+            })
+          end
+        end
+      end
+    end
+  end
+end
\ No newline at end of file
diff --git a/spec/arel/engines/sql/unit/relations/order_spec.rb b/spec/arel/engines/sql/unit/relations/order_spec.rb
new file mode 100644
index 0000000000..ce97a4dd5e
--- /dev/null
+++ b/spec/arel/engines/sql/unit/relations/order_spec.rb
@@ -0,0 +1,113 @@
+require File.join(File.dirname(__FILE__), '..', '..', '..', '..', '..', 'spec_helper')
+
+module Arel
+  describe Order do
+    before do
+      @relation = Table.new(:users)
+      @attribute = @relation[:id]
+    end
+
+    describe '#to_sql' do
+      describe "when given an attribute" do
+        it "manufactures sql with an order clause populated by the attribute" do
+          sql = Order.new(@relation, @attribute).to_sql
+
+          adapter_is :mysql do
+            sql.should be_like(%Q{
+              SELECT `users`.`id`, `users`.`name`
+              FROM `users`
+              ORDER BY `users`.`id` ASC
+            })
+          end
+
+          adapter_is_not :mysql do
+            sql.should be_like(%Q{
+              SELECT "users"."id", "users"."name"
+              FROM "users"
+              ORDER BY "users"."id" ASC
+            })
+          end
+        end
+      end
+
+      describe "when given multiple attributes" do
+        before do
+          @another_attribute = @relation[:name]
+        end
+
+        it "manufactures sql with an order clause populated by comma-separated attributes" do
+          sql = Order.new(@relation, @attribute, @another_attribute).to_sql
+
+          adapter_is :mysql do
+            sql.should be_like(%Q{
+              SELECT `users`.`id`, `users`.`name`
+              FROM `users`
+              ORDER BY `users`.`id` ASC, `users`.`name` ASC
+            })
+          end
+
+          adapter_is_not :mysql do
+            sql.should be_like(%Q{
+              SELECT "users"."id", "users"."name"
+              FROM "users"
+              ORDER BY "users"."id" ASC, "users"."name" ASC
+            })
+          end
+        end
+      end
+
+      describe "when given a string" do
+        before do
+          @string = "asdf"
+        end
+
+        it "passes the string through to the order clause" do
+          sql = Order.new(@relation, @string).to_sql
+
+          adapter_is :mysql do
+            sql.should be_like(%Q{
+              SELECT `users`.`id`, `users`.`name`
+              FROM `users`
+              ORDER BY asdf
+            })
+          end
+
+          adapter_is_not :mysql do
+            sql.should be_like(%Q{
+              SELECT "users"."id", "users"."name"
+              FROM "users"
+              ORDER BY asdf
+            })
+          end
+        end
+      end
+
+      describe "when ordering an ordered relation" do
+        before do
+          @ordered_relation = Order.new(@relation, @attribute)
+          @another_attribute = @relation[:name]
+        end
+
+        it "manufactures sql with the order clause of the last ordering preceding the first ordering" do
+          sql = Order.new(@ordered_relation, @another_attribute).to_sql
+
+          adapter_is :mysql do
+            sql.should be_like(%Q{
+              SELECT `users`.`id`, `users`.`name`
+              FROM `users`
+              ORDER BY `users`.`name` ASC, `users`.`id` ASC
+            })
+          end
+
+          adapter_is_not :mysql do
+            sql.should be_like(%Q{
+              SELECT "users"."id", "users"."name"
+              FROM "users"
+              ORDER BY "users"."name" ASC, "users"."id" ASC
+            })
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/spec/arel/engines/sql/unit/relations/project_spec.rb b/spec/arel/engines/sql/unit/relations/project_spec.rb
new file mode 100644
index 0000000000..9d6b9fab06
--- /dev/null
+++ b/spec/arel/engines/sql/unit/relations/project_spec.rb
@@ -0,0 +1,134 @@
+require File.join(File.dirname(__FILE__), '..', '..', '..', '..', '..', 'spec_helper')
+
+module Arel
+  describe Project do
+    before do
+      @relation = Table.new(:users)
+      @attribute = @relation[:id]
+    end
+
+    describe '#attributes' do
+      before do
+        @projection = Project.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 '#to_sql' do
+      describe 'when given an attribute' do
+        it "manufactures sql with a limited select clause" do
+          sql = Project.new(@relation, @attribute).to_sql
+
+          adapter_is :mysql do
+            sql.should be_like(%Q{
+              SELECT `users`.`id`
+              FROM `users`
+            })
+          end
+
+          adapter_is_not :mysql do
+            sql.should be_like(%Q{
+              SELECT "users"."id"
+              FROM "users"
+            })
+          end
+        end
+      end
+
+      describe 'when given a relation' do
+        before do
+          @scalar_relation = Project.new(@relation, @relation[:name])
+        end
+
+        it "manufactures sql with scalar selects" do
+          sql = Project.new(@relation, @scalar_relation).to_sql
+
+          adapter_is :mysql do
+            sql.should be_like(%Q{
+              SELECT (SELECT `users`.`name` FROM `users`) AS `users` FROM `users`
+            })
+          end
+
+          adapter_is_not :mysql do
+            sql.should be_like(%Q{
+              SELECT (SELECT "users"."name" FROM "users") AS "users" FROM "users"
+            })
+          end
+        end
+      end
+
+      describe 'when given a string' do
+        it "passes the string through to the select clause" do
+          sql = Project.new(@relation, 'asdf').to_sql
+
+          adapter_is :mysql do
+            sql.should be_like(%Q{
+              SELECT asdf FROM `users`
+            })
+          end
+
+          adapter_is_not :mysql do
+            sql.should be_like(%Q{
+              SELECT asdf FROM "users"
+            })
+          end
+        end
+      end
+
+      describe 'when given an expression' do
+        it 'manufactures sql with expressions' do
+          sql = @relation.project(@attribute.count).to_sql
+
+          adapter_is :mysql do
+            sql.should be_like(%Q{
+              SELECT COUNT(`users`.`id`) AS count_id
+              FROM `users`
+            })
+          end
+
+          adapter_is_not :mysql do
+            sql.should be_like(%Q{
+              SELECT COUNT("users"."id") AS count_id
+              FROM "users"
+            })
+          end
+        end
+
+        it 'manufactures sql with distinct expressions' do
+          sql = @relation.project(@attribute.count(true)).to_sql
+
+          adapter_is :mysql do
+            sql.should be_like(%Q{
+              SELECT COUNT(DISTINCT `users`.`id`) AS count_id
+              FROM `users`
+            })
+          end
+
+          adapter_is_not :mysql do
+            sql.should be_like(%Q{
+              SELECT COUNT(DISTINCT "users"."id") AS count_id
+              FROM "users"
+            })
+          end
+        end
+      end
+    end
+
+    describe '#externalizable?' do
+      describe 'when the projections are attributes' do
+        it 'returns false' do
+          Project.new(@relation, @attribute).should_not be_externalizable
+        end
+      end
+
+      describe 'when the projections include an aggregation' do
+        it "obtains" do
+          Project.new(@relation, @attribute.sum).should be_externalizable
+        end
+      end
+    end
+  end
+end
diff --git a/spec/arel/engines/sql/unit/relations/relation_spec.rb b/spec/arel/engines/sql/unit/relations/relation_spec.rb
new file mode 100644
index 0000000000..9a5cfbff41
--- /dev/null
+++ b/spec/arel/engines/sql/unit/relations/relation_spec.rb
@@ -0,0 +1,169 @@
+require File.join(File.dirname(__FILE__), '..', '..', '..', '..', '..', 'spec_helper')
+
+module Arel
+  describe Relation do
+    before do
+      @relation = Table.new(:users)
+      @attribute1 = @relation[:id]
+      @attribute2 = @relation[:name]
+    end
+
+    describe '[]' do
+      describe 'when given an', Attribute do
+        it "return the attribute congruent to the provided attribute" do
+          @relation[@attribute1].should == @attribute1
+        end
+      end
+
+      describe 'when given a', Symbol, String do
+        it "returns the attribute with the same name, if it exists" do
+          @relation[:id].should == @attribute1
+          @relation['id'].should == @attribute1
+          @relation[:does_not_exist].should be_nil
+        end
+      end
+    end
+
+    describe Relation::Operable do
+      describe 'joins' do
+        before do
+          @predicate = @relation[:id].eq(@relation[:id])
+        end
+
+        describe '#join' do
+          describe 'when given a relation' do
+            it "manufactures an inner join operation between those two relations" do
+              @relation.join(@relation).on(@predicate). \
+                should == InnerJoin.new(@relation, @relation, @predicate)
+            end
+          end
+
+          describe "when given a string" do
+            it "manufactures a join operation with the string passed through" do
+              @relation.join(arbitrary_string = "ASDF").should == Join.new(arbitrary_string, @relation)
+            end
+          end
+
+          describe "when given something blank" do
+            it "returns self" do
+              @relation.join.should == @relation
+            end
+          end
+        end
+
+        describe '#outer_join' do
+          it "manufactures a left outer join operation between those two relations" do
+            @relation.outer_join(@relation).on(@predicate). \
+              should == OuterJoin.new(@relation, @relation, @predicate)
+          end
+        end
+      end
+
+      describe '#project' do
+        it "manufactures a projection relation" do
+          @relation.project(@attribute1, @attribute2). \
+            should == Project.new(@relation, @attribute1, @attribute2)
+        end
+
+        describe "when given blank attributes" do
+          it "returns self" do
+            @relation.project.should == @relation
+          end
+        end
+      end
+
+      describe '#alias' do
+        it "manufactures an alias relation" do
+          @relation.alias.relation.should == Alias.new(@relation).relation
+        end
+      end
+
+      describe '#where' do
+        before do
+          @predicate = Equality.new(@attribute1, @attribute2)
+        end
+
+        it "manufactures a where relation" do
+          @relation.where(@predicate).should == Where.new(@relation, @predicate)
+        end
+
+        it "accepts arbitrary strings" do
+          @relation.where("arbitrary").should == Where.new(@relation, "arbitrary")
+        end
+
+        describe 'when given a blank predicate' do
+          it 'returns self' do
+            @relation.where.should == @relation
+          end
+        end
+      end
+
+      describe '#order' do
+        it "manufactures an order relation" do
+          @relation.order(@attribute1, @attribute2).should == Order.new(@relation, @attribute1, @attribute2)
+        end
+
+        describe 'when given a blank ordering' do
+          it 'returns self' do
+            @relation.order.should == @relation
+          end
+        end
+      end
+
+      describe '#take' do
+        it "manufactures a take relation" do
+          @relation.take(5).should == Take.new(@relation, 5)
+        end
+
+        describe 'when given a blank number of items' do
+          it 'returns self' do
+            @relation.take.should == @relation
+          end
+        end
+      end
+
+      describe '#skip' do
+        it "manufactures a skip relation" do
+          @relation.skip(4).should == Skip.new(@relation, 4)
+        end
+
+        describe 'when given a blank number of items' do
+          it 'returns self' do
+            @relation.skip.should == @relation
+          end
+        end
+      end
+
+      describe '#group' do
+        it 'manufactures a group relation' do
+          @relation.group(@attribute1, @attribute2).should == Group.new(@relation, @attribute1, @attribute2)
+        end
+
+        describe 'when given blank groupings' do
+          it 'returns self' do
+            @relation.group.should == @relation
+          end
+        end
+      end
+
+      describe Relation::Operable::Writable do
+        describe '#insert' do
+          it 'manufactures an insertion relation' do
+            Session.start do
+              record = {@relation[:name] => 'carl'}
+              mock(Session.new).create(Insert.new(@relation, record))
+              @relation.insert(record).should == @relation
+            end
+          end
+        end
+      end
+    end
+
+    describe Relation::Enumerable do
+      it "implements enumerable" do
+        @relation.collect.should == @relation.session.read(@relation)
+        @relation.first.should == @relation.session.read(@relation).first
+      end
+    end
+  end
+end
diff --git a/spec/arel/engines/sql/unit/relations/skip_spec.rb b/spec/arel/engines/sql/unit/relations/skip_spec.rb
new file mode 100644
index 0000000000..f8e5ceaad3
--- /dev/null
+++ b/spec/arel/engines/sql/unit/relations/skip_spec.rb
@@ -0,0 +1,32 @@
+require File.join(File.dirname(__FILE__), '..', '..', '..', '..', '..', 'spec_helper')
+
+module Arel
+  describe Skip do
+    before do
+      @relation = Table.new(:users)
+      @skipped = 4
+    end
+
+    describe '#to_sql' do
+      it "manufactures sql with limit and offset" do
+        sql = Skip.new(@relation, @skipped).to_sql
+
+        adapter_is :mysql do
+          sql.should be_like(%Q{
+            SELECT `users`.`id`, `users`.`name`
+            FROM `users`
+            OFFSET 4
+          })
+        end
+
+        adapter_is_not :mysql do
+          sql.should be_like(%Q{
+            SELECT "users"."id", "users"."name"
+            FROM "users"
+            OFFSET 4
+          })
+        end
+      end
+    end
+  end
+end
\ No newline at end of file
diff --git a/spec/arel/engines/sql/unit/relations/table_spec.rb b/spec/arel/engines/sql/unit/relations/table_spec.rb
new file mode 100644
index 0000000000..6de49a9157
--- /dev/null
+++ b/spec/arel/engines/sql/unit/relations/table_spec.rb
@@ -0,0 +1,99 @@
+require File.join(File.dirname(__FILE__), '..', '..', '..', '..', '..', 'spec_helper')
+
+module Arel
+  describe Table do
+    before do
+      @relation = Table.new(:users)
+    end
+
+    describe '[]' do
+      describe 'when given a', Symbol do
+        it "manufactures an attribute if the symbol names an attribute within the relation" do
+          @relation[:id].should == Attribute.new(@relation, :id)
+          @relation[:does_not_exist].should be_nil
+        end
+      end
+
+      describe 'when given an', Attribute do
+        it "returns the attribute if the attribute is within the relation" do
+          @relation[@relation[:id]].should == @relation[:id]
+        end
+
+        it "returns nil if the attribtue is not within the relation" do
+          another_relation = Table.new(:photos)
+          @relation[another_relation[:id]].should be_nil
+        end
+      end
+
+      describe 'when given an', Expression do
+        before do
+          @expression = @relation[:id].count
+        end
+
+        it "returns the Expression if the Expression is within the relation" do
+          @relation[@expression].should be_nil
+        end
+      end
+    end
+
+    describe '#to_sql' do
+      it "manufactures a simple select query" do
+        sql = @relation.to_sql
+
+        adapter_is :mysql do
+          sql.should be_like(%Q{
+            SELECT `users`.`id`, `users`.`name`
+            FROM `users`
+          })
+        end
+
+        adapter_is_not :mysql do
+          sql.should be_like(%Q{
+            SELECT "users"."id", "users"."name"
+            FROM "users"
+          })
+        end
+      end
+    end
+
+    describe '#column_for' do
+      it "returns the column corresponding to the attribute" do
+        @relation.column_for(@relation[:id]).should == @relation.columns.detect { |c| c.name == 'id' }
+      end
+    end
+
+    describe '#attributes' do
+      it 'manufactures attributes corresponding to columns in the table' do
+        @relation.attributes.should == [
+          Attribute.new(@relation, :id),
+          Attribute.new(@relation, :name)
+        ]
+      end
+
+      describe '#reset' do
+        it "reloads columns from the database" do
+          lambda { stub(@relation.engine).columns { [] } }.should_not change { @relation.attributes }
+          lambda { @relation.reset                       }.should     change { @relation.attributes }
+        end
+      end
+    end
+
+    describe 'hashing' do
+      it "implements hash equality" do
+        Table.new(:users).should     hash_the_same_as(Table.new(:users))
+        Table.new(:users).should_not hash_the_same_as(Table.new(:photos))
+      end
+    end
+
+    describe '#engine' do
+      it "defaults to global engine" do
+        Table.engine = engine = Sql::Engine.new
+        Table.new(:users).engine.should == engine
+      end
+
+      it "can be specified" do
+        Table.new(:users, engine = Sql::Engine.new).engine.should == engine
+      end
+    end
+  end
+end
\ No newline at end of file
diff --git a/spec/arel/engines/sql/unit/relations/take_spec.rb b/spec/arel/engines/sql/unit/relations/take_spec.rb
new file mode 100644
index 0000000000..1263ed4795
--- /dev/null
+++ b/spec/arel/engines/sql/unit/relations/take_spec.rb
@@ -0,0 +1,32 @@
+require File.join(File.dirname(__FILE__), '..', '..', '..', '..', '..', 'spec_helper')
+
+module Arel
+  describe Take do
+    before do
+      @relation = Table.new(:users)
+      @taken = 4
+    end
+
+    describe '#to_sql' do
+      it "manufactures sql with limit and offset" do
+        sql = Take.new(@relation, @taken).to_sql
+
+        adapter_is :mysql do
+          sql.should be_like(%Q{
+            SELECT `users`.`id`, `users`.`name`
+            FROM `users`
+            LIMIT 4
+          })
+        end
+
+        adapter_is_not :mysql do
+          sql.should be_like(%Q{
+            SELECT "users"."id", "users"."name"
+            FROM "users"
+            LIMIT 4
+          })
+        end
+      end
+    end
+  end
+end
\ No newline at end of file
diff --git a/spec/arel/engines/sql/unit/relations/update_spec.rb b/spec/arel/engines/sql/unit/relations/update_spec.rb
new file mode 100644
index 0000000000..f553490ef5
--- /dev/null
+++ b/spec/arel/engines/sql/unit/relations/update_spec.rb
@@ -0,0 +1,121 @@
+require File.join(File.dirname(__FILE__), '..', '..', '..', '..', '..', 'spec_helper')
+
+module Arel
+  describe Update do
+    before do
+      @relation = Table.new(:users)
+    end
+
+    describe '#to_sql' do
+      it "manufactures sql updating attributes when given multiple attributes" do
+        sql = Update.new(@relation, @relation[:id] => 1, @relation[:name] => "nick").to_sql
+
+        adapter_is :mysql do
+          sql.should be_like(%Q{
+            UPDATE `users`
+            SET `id` = 1, `name` = 'nick'
+          })
+        end
+
+        adapter_is_not :mysql do
+          sql.should be_like(%Q{
+            UPDATE "users"
+            SET "id" = 1, "name" = 'nick'
+          })
+        end
+      end
+
+      it "manufactures sql updating attributes when given a ranged relation" do
+        sql = Update.new(@relation.take(1), @relation[:name] => "nick").to_sql
+
+        adapter_is :mysql do
+          sql.should be_like(%Q{
+            UPDATE `users`
+            SET `name` = 'nick'
+            LIMIT 1
+          })
+        end
+
+        adapter_is_not :mysql do
+          sql.should be_like(%Q{
+            UPDATE "users"
+            SET "name" = 'nick'
+            LIMIT 1
+          })
+        end
+      end
+
+      describe 'when given values whose types correspond to the types of the attributes' do
+        before do
+          @update = Update.new(@relation, @relation[:name] => "nick")
+        end
+
+        it 'manufactures sql updating attributes' do
+          adapter_is :mysql do
+            @update.to_sql.should be_like(%Q{
+              UPDATE `users`
+              SET `name` = 'nick'
+            })
+          end
+
+          adapter_is_not :mysql do
+            @update.to_sql.should be_like(%Q{
+              UPDATE "users"
+              SET "name" = 'nick'
+            })
+          end
+        end
+      end
+
+      describe 'when given values whose types differ from from the types of the attributes' do
+        before do
+          @update = Update.new(@relation, @relation[:id] => '1-asdf')
+        end
+
+        it 'manufactures sql updating attributes' do
+          adapter_is :mysql do
+            @update.to_sql.should be_like(%Q{
+              UPDATE `users`
+              SET `id` = 1
+            })
+          end
+
+          adapter_is_not :mysql do
+            @update.to_sql.should be_like(%Q{
+              UPDATE "users"
+              SET "id" = 1
+            })
+          end
+        end
+      end
+
+      describe 'when the relation is a where' do
+        before do
+          @update = Update.new(
+            @relation.where(@relation[:id].eq(1)),
+            @relation[:name] => "nick"
+          )
+        end
+
+        it 'manufactures sql updating a where relation' do
+          adapter_is :mysql do
+            @update.to_sql.should be_like(%Q{
+              UPDATE `users`
+              SET `name` = 'nick'
+              WHERE `users`.`id` = 1
+            })
+          end
+
+          adapter_is_not :mysql do
+            @update.to_sql.should be_like(%Q{
+              UPDATE "users"
+              SET "name" = 'nick'
+              WHERE "users"."id" = 1
+            })
+          end
+        end
+      end
+    end
+
+  end
+end
diff --git a/spec/arel/engines/sql/unit/relations/where_spec.rb b/spec/arel/engines/sql/unit/relations/where_spec.rb
new file mode 100644
index 0000000000..5870b6b793
--- /dev/null
+++ b/spec/arel/engines/sql/unit/relations/where_spec.rb
@@ -0,0 +1,64 @@
+require File.join(File.dirname(__FILE__), '..', '..', '..', '..', '..', 'spec_helper')
+
+module Arel
+  describe Where do
+    before do
+      @relation = Table.new(:users)
+      @predicate = @relation[:id].eq(1)
+    end
+
+    describe '#initialize' do
+      it "manufactures nested where relations if multiple predicates are provided" do
+        another_predicate = @relation[:name].lt(2)
+        Where.new(@relation, @predicate, another_predicate). \
+          should == Where.new(Where.new(@relation, another_predicate), @predicate)
+      end
+    end
+
+    describe '#to_sql' do
+      describe 'when given a predicate' do
+        it "manufactures sql with where clause conditions" do
+          sql = Where.new(@relation, @predicate).to_sql
+
+          adapter_is :mysql do
+            sql.should be_like(%Q{
+              SELECT `users`.`id`, `users`.`name`
+              FROM `users`
+              WHERE `users`.`id` = 1
+            })
+          end
+
+          adapter_is_not :mysql do
+            sql.should be_like(%Q{
+              SELECT "users"."id", "users"."name"
+              FROM "users"
+              WHERE "users"."id" = 1
+            })
+          end
+        end
+      end
+
+      describe 'when given a string' do
+        it "passes the string through to the where clause" do
+          sql = Where.new(@relation, 'asdf').to_sql
+
+          adapter_is :mysql do
+            sql.should be_like(%Q{
+              SELECT `users`.`id`, `users`.`name`
+              FROM `users`
+              WHERE asdf
+            })
+          end
+
+          adapter_is_not :mysql do
+            sql.should be_like(%Q{
+              SELECT "users"."id", "users"."name"
+              FROM "users"
+              WHERE asdf
+            })
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/spec/arel/engines/sql/unit/session/session_spec.rb b/spec/arel/engines/sql/unit/session/session_spec.rb
new file mode 100644
index 0000000000..c489984a61
--- /dev/null
+++ b/spec/arel/engines/sql/unit/session/session_spec.rb
@@ -0,0 +1,84 @@
+require File.join(File.dirname(__FILE__), '..', '..', '..', '..', '..', 'spec_helper')
+
+module Arel
+  describe Session do
+    before do
+      @relation = Table.new(:users)
+      @session = Session.new
+    end
+
+    describe '::start' do
+      describe '::instance' do
+        it "it is a singleton within the started session" do
+          Session.start do
+            Session.new.should == Session.new
+          end
+        end
+
+        it "is a singleton across nested sessions" do
+          Session.start do
+            outside = Session.new
+            Session.start do
+              Session.new.should == outside
+            end
+          end
+        end
+
+        it "manufactures new sessions outside of the started session" do
+          Session.new.should_not == Session.new
+        end
+      end
+    end
+
+    describe Session::CRUD do
+      before do
+        @insert = Insert.new(@relation, @relation[:name] => 'nick')
+        @update = Update.new(@relation, @relation[:name] => 'nick')
+        @delete = Deletion.new(@relation)
+        @read = @relation
+      end
+
+      describe '#create' do
+        it "executes an insertion on the connection" do
+          mock(@insert).call
+          @session.create(@insert)
+        end
+      end
+
+      describe '#read' do
+        it "executes an selection on the connection" do
+          mock(@read).call
+          @session.read(@read)
+        end
+
+        it "is memoized" do
+          mock(@read).call.once
+          @session.read(@read)
+          @session.read(@read)
+        end
+      end
+
+      describe '#update' do
+        it "executes an update on the connection" do
+          mock(@update).call
+          @session.update(@update)
+        end
+      end
+
+      describe '#delete' do
+        it "executes a delete on the connection" do
+          mock(@delete).call
+          @session.delete(@delete)
+        end
+      end
+    end
+
+    describe 'Transactions' do
+      describe '#begin' do
+      end
+
+      describe '#end' do
+      end
+    end
+  end
+end