1 files changed, 167 insertions, 0 deletions
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
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+++ 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