Merge branch 'master' into activestorage-guide

26 files changed, 385 insertions, 179 deletions

diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md
index 4aa7ecfc7e..e6a41ec281 100644
--- a/activerecord/CHANGELOG.md
+++ b/activerecord/CHANGELOG.md
@@ -1,3 +1,11 @@
+*   Fix `bin/rails db:migrate` with specified `VERSION`.
+    `bin/rails db:migrate` with empty VERSION behaves as without `VERSION`.
+    Check a format of `VERSION`: Allow a migration version number
+    or name of a migration file. Raise error if format of `VERSION` is invalid.
+    Raise error if target migration doesn't exist.
+
+    *bogdanvlviv*
+
 *   Fixed a bug where column orders for an index weren't written to
     db/schema.rb when using the sqlite adapter.
 
diff --git a/activerecord/lib/active_record/associations.rb b/activerecord/lib/active_record/associations.rb
index bc7e288500..661605d3e5 100644
--- a/activerecord/lib/active_record/associations.rb
+++ b/activerecord/lib/active_record/associations.rb
@@ -140,26 +140,6 @@ module ActiveRecord
   class HasOneThroughCantAssociateThroughHasOneOrManyReflection < ThroughCantAssociateThroughHasOneOrManyReflection #:nodoc:
   end
 
-  class HasManyThroughCantAssociateNewRecords < ActiveRecordError #:nodoc:
-    def initialize(owner = nil, reflection = nil)
-      if owner && reflection
-        super("Cannot associate new records through '#{owner.class.name}##{reflection.name}' on '#{reflection.source_reflection.class_name rescue nil}##{reflection.source_reflection.name rescue nil}'. Both records must have an id in order to create the has_many :through record associating them.")
-      else
-        super("Cannot associate new records.")
-      end
-    end
-  end
-
-  class HasManyThroughCantDissociateNewRecords < ActiveRecordError #:nodoc:
-    def initialize(owner = nil, reflection = nil)
-      if owner && reflection
-        super("Cannot dissociate new records through '#{owner.class.name}##{reflection.name}' on '#{reflection.source_reflection.class_name rescue nil}##{reflection.source_reflection.name rescue nil}'. Both records must have an id in order to delete the has_many :through record associating them.")
-      else
-        super("Cannot dissociate new records.")
-      end
-    end
-  end
-
   class ThroughNestedAssociationsAreReadonly < ActiveRecordError #:nodoc:
     def initialize(owner = nil, reflection = nil)
       if owner && reflection
@@ -189,16 +169,6 @@ module ActiveRecord
     end
   end
 
-  class ReadOnlyAssociation < ActiveRecordError #:nodoc:
-    def initialize(reflection = nil)
-      if reflection
-        super("Cannot add to a has_many :through association. Try adding to #{reflection.through_reflection.name.inspect}.")
-      else
-        super("Read-only reflection error.")
-      end
-    end
-  end
-
   # This error is raised when trying to destroy a parent instance in N:1 or 1:1 associations
   # (has_many, has_one) when there is at least 1 child associated instance.
   # ex: if @project.tasks.size > 0, DeleteRestrictionError will be raised when trying to destroy @project
diff --git a/activerecord/lib/active_record/associations/preloader.rb b/activerecord/lib/active_record/associations/preloader.rb
index e1754d4a19..5a93a89d0a 100644
--- a/activerecord/lib/active_record/associations/preloader.rb
+++ b/activerecord/lib/active_record/associations/preloader.rb
@@ -166,8 +166,6 @@ module ActiveRecord
         end
 
         class AlreadyLoaded # :nodoc:
-          attr_reader :owners, :reflection
-
           def initialize(klass, owners, reflection, preload_scope)
             @owners = owners
             @reflection = reflection
@@ -178,6 +176,9 @@ module ActiveRecord
           def preloaded_records
             owners.flat_map { |owner| owner.association(reflection.name).target }
           end
+
+          protected
+            attr_reader :owners, :reflection
         end
 
         # Returns a class containing the logic needed to load preload the data
diff --git a/activerecord/lib/active_record/associations/preloader/association.rb b/activerecord/lib/active_record/associations/preloader/association.rb
index 607d376a08..19c337dc39 100644
--- a/activerecord/lib/active_record/associations/preloader/association.rb
+++ b/activerecord/lib/active_record/associations/preloader/association.rb
@@ -4,7 +4,6 @@ module ActiveRecord
   module Associations
     class Preloader
       class Association #:nodoc:
-        attr_reader :owners, :reflection, :preload_scope, :model, :klass
         attr_reader :preloaded_records
 
         def initialize(klass, owners, reflection, preload_scope)
@@ -17,11 +16,20 @@ module ActiveRecord
         end
 
         def run(preloader)
-          associated_records_by_owner(preloader).each do |owner, records|
-            associate_records_to_owner(owner, records)
+          records = load_records do |record|
+            owner = owners_by_key[convert_key(record[association_key_name])]
+            association = owner.association(reflection.name)
+            association.set_inverse_instance(record)
+          end
+
+          owners.each do |owner|
+            associate_records_to_owner(owner, records[convert_key(owner[owner_key_name])] || [])
           end
         end
 
+        protected
+          attr_reader :owners, :reflection, :preload_scope, :model, :klass
+
         private
           # The name of the key on the associated records
           def association_key_name
@@ -33,18 +41,6 @@ module ActiveRecord
             reflection.join_foreign_key
           end
 
-          def associated_records_by_owner(preloader)
-            records = load_records do |record|
-              owner = owners_by_key[convert_key(record[association_key_name])]
-              association = owner.association(reflection.name)
-              association.set_inverse_instance(record)
-            end
-
-            owners.each_with_object({}) do |owner, result|
-              result[owner] = records[convert_key(owner[owner_key_name])] || []
-            end
-          end
-
           def associate_records_to_owner(owner, records)
             raise NotImplementedError
           end
diff --git a/activerecord/lib/active_record/associations/preloader/has_many_through.rb b/activerecord/lib/active_record/associations/preloader/has_many_through.rb
index 0639fdca44..3e17d07a33 100644
--- a/activerecord/lib/active_record/associations/preloader/has_many_through.rb
+++ b/activerecord/lib/active_record/associations/preloader/has_many_through.rb
@@ -5,16 +5,6 @@ module ActiveRecord
     class Preloader
       class HasManyThrough < CollectionAssociation #:nodoc:
         include ThroughAssociation
-
-        def associated_records_by_owner(preloader)
-          records_by_owner = super
-
-          if reflection_scope.distinct_value
-            records_by_owner.each_value(&:uniq!)
-          end
-
-          records_by_owner
-        end
       end
     end
   end
diff --git a/activerecord/lib/active_record/associations/preloader/through_association.rb b/activerecord/lib/active_record/associations/preloader/through_association.rb
index fa32cc5553..762275fbad 100644
--- a/activerecord/lib/active_record/associations/preloader/through_association.rb
+++ b/activerecord/lib/active_record/associations/preloader/through_association.rb
@@ -4,77 +4,53 @@ module ActiveRecord
   module Associations
     class Preloader
       module ThroughAssociation #:nodoc:
-        def through_reflection
-          reflection.through_reflection
-        end
-
-        def source_reflection
-          reflection.source_reflection
-        end
-
-        def associated_records_by_owner(preloader)
-          through_scope = through_scope()
-
-          preloader.preload(owners,
-                            through_reflection.name,
-                            through_scope)
-
-          through_records = owners.map do |owner|
-            center = owner.association(through_reflection.name).target
-            [owner, Array(center)]
-          end
-
-          reset_association(owners, through_reflection.name, through_scope)
-
-          middle_records = through_records.flat_map(&:last)
-
-          reflection_scope = reflection_scope() if reflection.scope
-
-          preloaders = preloader.preload(middle_records,
-                                         source_reflection.name,
-                                         reflection_scope)
-
+        def run(preloader)
+          already_loaded     = owners.first.association(through_reflection.name).loaded?
+          through_scope      = through_scope()
+          reflection_scope   = target_reflection_scope
+          through_preloaders = preloader.preload(owners, through_reflection.name, through_scope)
+          middle_records     = through_preloaders.flat_map(&:preloaded_records)
+          preloaders         = preloader.preload(middle_records, source_reflection.name, reflection_scope)
           @preloaded_records = preloaders.flat_map(&:preloaded_records)
 
-          middle_to_pl = preloaders.each_with_object({}) do |pl, h|
-            pl.owners.each { |middle|
-              h[middle] = pl
-            }
-          end
-
-          through_records.each_with_object({}) do |(lhs, center), records_by_owner|
-            pl_to_middle = center.group_by { |record| middle_to_pl[record] }
-
-            records_by_owner[lhs] = pl_to_middle.flat_map do |pl, middles|
-              rhs_records = middles.flat_map { |r|
-                r.association(source_reflection.name).target
-              }.compact
-
-              # Respect the order on `reflection_scope` if it exists, else use the natural order.
-              if reflection_scope && !reflection_scope.order_values.empty?
-                @id_map ||= id_to_index_map @preloaded_records
-                rhs_records.sort_by { |rhs| @id_map[rhs] }
-              else
-                rhs_records
+          owners.each do |owner|
+            through_records = Array(owner.association(through_reflection.name).target)
+            if already_loaded
+              if source_type = reflection.options[:source_type]
+                through_records = through_records.select do |record|
+                  record[reflection.foreign_type] == source_type
+                end
               end
+            else
+              owner.association(through_reflection.name).reset if through_scope
+            end
+            result = through_records.flat_map do |record|
+              association = record.association(source_reflection.name)
+              target = association.target
+              association.reset if preload_scope
+              target
             end
+            result.compact!
+            if reflection_scope
+              result.sort_by! { |rhs| preload_index[rhs] } if reflection_scope.order_values.any?
+              result.uniq! if reflection_scope.distinct_value
+            end
+            associate_records_to_owner(owner, result)
           end
         end
 
         private
+          def through_reflection
+            reflection.through_reflection
+          end
 
-          def id_to_index_map(ids)
-            id_map = {}
-            ids.each_with_index { |id, index| id_map[id] = index }
-            id_map
+          def source_reflection
+            reflection.source_reflection
           end
 
-          def reset_association(owners, association_name, should_reset)
-            # Don't cache the association - we would only be caching a subset
-            if should_reset
-              owners.each { |owner|
-                owner.association(association_name).reset
-              }
+          def preload_index
+            @preload_index ||= @preloaded_records.each_with_object({}).with_index do |(id, result), index|
+              result[id] = index
             end
           end
 
@@ -115,6 +91,16 @@ module ActiveRecord
 
             scope unless scope.empty_scope?
           end
+
+          def target_reflection_scope
+            if preload_scope
+              reflection_scope.merge(preload_scope)
+            elsif reflection.scope
+              reflection_scope
+            else
+              nil
+            end
+          end
       end
     end
   end
diff --git a/activerecord/lib/active_record/collection_cache_key.rb b/activerecord/lib/active_record/collection_cache_key.rb
index f3e6516414..88b398ad45 100644
--- a/activerecord/lib/active_record/collection_cache_key.rb
+++ b/activerecord/lib/active_record/collection_cache_key.rb
@@ -12,6 +12,9 @@ module ActiveRecord
           timestamp = collection.max_by(&timestamp_column)._read_attribute(timestamp_column)
         end
       else
+        if collection.eager_loading?
+          collection = collection.send(:apply_join_dependency)
+        end
         column_type = type_for_attribute(timestamp_column.to_s)
         column = connection.column_name_from_arel_node(collection.arel_attribute(timestamp_column))
         select_values = "COUNT(*) AS #{connection.quote_column_name("size")}, MAX(%s) AS timestamp"
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/transaction.rb b/activerecord/lib/active_record/connection_adapters/abstract/transaction.rb
index 147e16e9fa..d9ac8db6a8 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/transaction.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/transaction.rb
@@ -240,7 +240,7 @@ module ActiveRecord
                 rollback_transaction if transaction
               else
                 begin
-                  commit_transaction
+                  commit_transaction if transaction
                 rescue Exception
                   rollback_transaction(transaction) unless transaction.state.completed?
                   raise
diff --git a/activerecord/lib/active_record/migration.rb b/activerecord/lib/active_record/migration.rb
index 1485687053..d12a979a7f 100644
--- a/activerecord/lib/active_record/migration.rb
+++ b/activerecord/lib/active_record/migration.rb
@@ -1224,7 +1224,7 @@ module ActiveRecord
 
       # Return true if a valid version is not provided.
       def invalid_target?
-        !target && @target_version && @target_version > 0
+        @target_version && @target_version != 0 && !target
       end
 
       def execute_migration_in_transaction(migration, direction)
diff --git a/activerecord/lib/active_record/railties/databases.rake b/activerecord/lib/active_record/railties/databases.rake
index 723272b4b2..3bca2982e0 100644
--- a/activerecord/lib/active_record/railties/databases.rake
+++ b/activerecord/lib/active_record/railties/databases.rake
@@ -97,16 +97,27 @@ db_namespace = namespace :db do
     task up: [:environment, :load_config] do
       raise "VERSION is required" if !ENV["VERSION"] || ENV["VERSION"].empty?
 
-      version = ENV["VERSION"] ? ENV["VERSION"].to_i : nil
-      ActiveRecord::Migrator.run(:up, ActiveRecord::Tasks::DatabaseTasks.migrations_paths, version)
+      ActiveRecord::Tasks::DatabaseTasks.check_target_version
+
+      ActiveRecord::Migrator.run(
+        :up,
+        ActiveRecord::Tasks::DatabaseTasks.migrations_paths,
+        ActiveRecord::Tasks::DatabaseTasks.target_version
+      )
       db_namespace["_dump"].invoke
     end
 
     # desc 'Runs the "down" for a given migration VERSION.'
     task down: [:environment, :load_config] do
       raise "VERSION is required - To go down one migration, use db:rollback" if !ENV["VERSION"] || ENV["VERSION"].empty?
-      version = ENV["VERSION"] ? ENV["VERSION"].to_i : nil
-      ActiveRecord::Migrator.run(:down, ActiveRecord::Tasks::DatabaseTasks.migrations_paths, version)
+
+      ActiveRecord::Tasks::DatabaseTasks.check_target_version
+
+      ActiveRecord::Migrator.run(
+        :down,
+        ActiveRecord::Tasks::DatabaseTasks.migrations_paths,
+        ActiveRecord::Tasks::DatabaseTasks.target_version
+      )
       db_namespace["_dump"].invoke
     end
 
diff --git a/activerecord/lib/active_record/relation.rb b/activerecord/lib/active_record/relation.rb
index 997cfe4b5e..7615fb6ee9 100644
--- a/activerecord/lib/active_record/relation.rb
+++ b/activerecord/lib/active_record/relation.rb
@@ -359,6 +359,11 @@ module ActiveRecord
     def update_all(updates)
       raise ArgumentError, "Empty list of attributes to change" if updates.blank?
 
+      if eager_loading?
+        relation = apply_join_dependency
+        return relation.update_all(updates)
+      end
+
       stmt = Arel::UpdateManager.new
 
       stmt.set Arel.sql(@klass.send(:sanitize_sql_for_assignment, updates))
@@ -423,6 +428,11 @@ module ActiveRecord
         raise ActiveRecordError.new("delete_all doesn't support #{invalid_methods.join(', ')}")
       end
 
+      if eager_loading?
+        relation = apply_join_dependency
+        return relation.delete_all
+      end
+
       stmt = Arel::DeleteManager.new
       stmt.from(table)
 
diff --git a/activerecord/lib/active_record/relation/calculations.rb b/activerecord/lib/active_record/relation/calculations.rb
index 116bddce85..11256ab3d9 100644
--- a/activerecord/lib/active_record/relation/calculations.rb
+++ b/activerecord/lib/active_record/relation/calculations.rb
@@ -130,7 +130,7 @@ module ActiveRecord
     #      end
     def calculate(operation, column_name)
       if has_include?(column_name)
-        relation = apply_join_dependency(construct_join_dependency)
+        relation = apply_join_dependency
         relation.distinct! if operation.to_s.downcase == "count"
 
         relation.calculate(operation, column_name)
@@ -180,7 +180,7 @@ module ActiveRecord
       end
 
       if has_include?(column_names.first)
-        relation = apply_join_dependency(construct_join_dependency)
+        relation = apply_join_dependency
         relation.pluck(*column_names)
       else
         relation = spawn
diff --git a/activerecord/lib/active_record/relation/finder_methods.rb b/activerecord/lib/active_record/relation/finder_methods.rb
index 707245bab2..18566b5662 100644
--- a/activerecord/lib/active_record/relation/finder_methods.rb
+++ b/activerecord/lib/active_record/relation/finder_methods.rb
@@ -394,7 +394,7 @@ module ActiveRecord
         )
       end
 
-      def apply_join_dependency(join_dependency)
+      def apply_join_dependency(join_dependency = construct_join_dependency)
         relation = except(:includes, :eager_load, :preload).joins!(join_dependency)
 
         if using_limitable_reflections?(join_dependency.reflections)
diff --git a/activerecord/lib/active_record/scoping/named.rb b/activerecord/lib/active_record/scoping/named.rb
index 6fa096c1fe..310af72c41 100644
--- a/activerecord/lib/active_record/scoping/named.rb
+++ b/activerecord/lib/active_record/scoping/named.rb
@@ -24,8 +24,14 @@ module ActiveRecord
         # You can define a scope that applies to all finders using
         # {default_scope}[rdoc-ref:Scoping::Default::ClassMethods#default_scope].
         def all
+          current_scope = self.current_scope
+
           if current_scope
-            current_scope.clone
+            if self == current_scope.klass
+              current_scope.clone
+            else
+              relation.merge!(current_scope)
+            end
           else
             default_scoped
           end
diff --git a/activerecord/lib/active_record/tasks/database_tasks.rb b/activerecord/lib/active_record/tasks/database_tasks.rb
index ff388ff1f6..4657e51e6d 100644
--- a/activerecord/lib/active_record/tasks/database_tasks.rb
+++ b/activerecord/lib/active_record/tasks/database_tasks.rb
@@ -164,13 +164,12 @@ module ActiveRecord
       end
 
       def migrate
-        raise "Empty VERSION provided" if ENV["VERSION"] && ENV["VERSION"].empty?
+        check_target_version
 
         verbose = ENV["VERBOSE"] ? ENV["VERBOSE"] != "false" : true
-        version = ENV["VERSION"] ? ENV["VERSION"].to_i : nil
         scope = ENV["SCOPE"]
         verbose_was, Migration.verbose = Migration.verbose, verbose
-        Migrator.migrate(migrations_paths, version) do |migration|
+        Migrator.migrate(migrations_paths, target_version) do |migration|
           scope.blank? || scope == migration.scope
         end
         ActiveRecord::Base.clear_cache!
@@ -178,6 +177,16 @@ module ActiveRecord
         Migration.verbose = verbose_was
       end
 
+      def check_target_version
+        if target_version && !(Migration::MigrationFilenameRegexp.match?(ENV["VERSION"]) || /\A\d+\z/.match?(ENV["VERSION"]))
+          raise "Invalid format of target version: `VERSION=#{ENV['VERSION']}`"
+        end
+      end
+
+      def target_version
+        ENV["VERSION"].to_i if ENV["VERSION"] && !ENV["VERSION"].empty?
+      end
+
       def charset_current(environment = env)
         charset ActiveRecord::Base.configurations[environment]
       end
diff --git a/activerecord/test/cases/associations/nested_through_associations_test.rb b/activerecord/test/cases/associations/nested_through_associations_test.rb
index 4cf5a9ffc4..65d30d011b 100644
--- a/activerecord/test/cases/associations/nested_through_associations_test.rb
+++ b/activerecord/test/cases/associations/nested_through_associations_test.rb
@@ -579,6 +579,28 @@ class NestedThroughAssociationsTest < ActiveRecord::TestCase
     assert !c.post_taggings.empty?
   end
 
+  def test_polymorphic_has_many_through_when_through_association_has_not_loaded
+    cake_designer = CakeDesigner.create!(chef: Chef.new)
+    drink_designer = DrinkDesigner.create!(chef: Chef.new)
+    department = Department.create!(chefs: [cake_designer.chef, drink_designer.chef])
+    Hotel.create!(departments: [department])
+    hotel = Hotel.includes(:cake_designers, :drink_designers).take
+
+    assert_equal [cake_designer], hotel.cake_designers
+    assert_equal [drink_designer], hotel.drink_designers
+  end
+
+  def test_polymorphic_has_many_through_when_through_association_has_already_loaded
+    cake_designer = CakeDesigner.create!(chef: Chef.new)
+    drink_designer = DrinkDesigner.create!(chef: Chef.new)
+    department = Department.create!(chefs: [cake_designer.chef, drink_designer.chef])
+    Hotel.create!(departments: [department])
+    hotel = Hotel.includes(:chefs, :cake_designers, :drink_designers).take
+
+    assert_equal [cake_designer], hotel.cake_designers
+    assert_equal [drink_designer], hotel.drink_designers
+  end
+
   def test_polymorphic_has_many_through_joined_different_table_twice
     cake_designer = CakeDesigner.create!(chef: Chef.new)
     drink_designer = DrinkDesigner.create!(chef: Chef.new)
diff --git a/activerecord/test/cases/collection_cache_key_test.rb b/activerecord/test/cases/collection_cache_key_test.rb
index c137693211..19d6464a22 100644
--- a/activerecord/test/cases/collection_cache_key_test.rb
+++ b/activerecord/test/cases/collection_cache_key_test.rb
@@ -73,6 +73,16 @@ module ActiveRecord
       assert_equal last_developer_timestamp.to_s(ActiveRecord::Base.cache_timestamp_format), $3
     end
 
+    test "cache_key for relation with includes" do
+      comments = Comment.includes(:post).where("posts.type": "Post")
+      assert_match(/\Acomments\/query-(\h+)-(\d+)-(\d+)\z/, comments.cache_key)
+    end
+
+    test "cache_key for loaded relation with includes" do
+      comments = Comment.includes(:post).where("posts.type": "Post").load
+      assert_match(/\Acomments\/query-(\h+)-(\d+)-(\d+)\z/, comments.cache_key)
+    end
+
     test "it triggers at most one query" do
       developers = Developer.where(name: "David")
 
diff --git a/activerecord/test/cases/locking_test.rb b/activerecord/test/cases/locking_test.rb
index 6791d50940..e857180bd1 100644
--- a/activerecord/test/cases/locking_test.rb
+++ b/activerecord/test/cases/locking_test.rb
@@ -611,14 +611,12 @@ unless in_memory_db?
       end
     end
 
-    if current_adapter?(:PostgreSQLAdapter, :OracleAdapter)
-      def test_no_locks_no_wait
-        first, second = duel { Person.find 1 }
-        assert first.end > second.end
-      end
-
-      private
+    def test_no_locks_no_wait
+      first, second = duel { Person.find 1 }
+      assert first.end > second.end
+    end
 
+    private
       def duel(zzz = 5)
         t0, t1, t2, t3 = nil, nil, nil, nil
 
@@ -646,6 +644,5 @@ unless in_memory_db?
         assert t3 > t2
         [t0.to_f..t1.to_f, t2.to_f..t3.to_f]
       end
-    end
   end
 end
diff --git a/activerecord/test/cases/migrator_test.rb b/activerecord/test/cases/migrator_test.rb
index ee10be119c..1047ba1367 100644
--- a/activerecord/test/cases/migrator_test.rb
+++ b/activerecord/test/cases/migrator_test.rb
@@ -66,6 +66,26 @@ class MigratorTest < ActiveRecord::TestCase
       list = [ActiveRecord::Migration.new("Foo", 1), ActiveRecord::Migration.new("Bar", 2)]
       ActiveRecord::Migrator.new(:up, list, 3).run
     end
+
+    assert_raises(ActiveRecord::UnknownMigrationVersionError) do
+      list = [ActiveRecord::Migration.new("Foo", 1), ActiveRecord::Migration.new("Bar", 2)]
+      ActiveRecord::Migrator.new(:up, list, -1).run
+    end
+
+    assert_raises(ActiveRecord::UnknownMigrationVersionError) do
+      list = [ActiveRecord::Migration.new("Foo", 1), ActiveRecord::Migration.new("Bar", 2)]
+      ActiveRecord::Migrator.new(:up, list, 0).run
+    end
+
+    assert_raises(ActiveRecord::UnknownMigrationVersionError) do
+      list = [ActiveRecord::Migration.new("Foo", 1), ActiveRecord::Migration.new("Bar", 2)]
+      ActiveRecord::Migrator.new(:up, list, 3).migrate
+    end
+
+    assert_raises(ActiveRecord::UnknownMigrationVersionError) do
+      list = [ActiveRecord::Migration.new("Foo", 1), ActiveRecord::Migration.new("Bar", 2)]
+      ActiveRecord::Migrator.new(:up, list, -1).migrate
+    end
   end
 
   def test_finds_migrations
diff --git a/activerecord/test/cases/persistence_test.rb b/activerecord/test/cases/persistence_test.rb
index 6cbe18cc8c..f088c064f5 100644
--- a/activerecord/test/cases/persistence_test.rb
+++ b/activerecord/test/cases/persistence_test.rb
@@ -94,27 +94,31 @@ class PersistenceTest < ActiveRecord::TestCase
   end
 
   def test_delete_all_with_joins_and_where_part_is_hash
-    where_args = { toys: { name: "Bone" } }
-    count = Pet.joins(:toys).where(where_args).count
+    pets = Pet.joins(:toys).where(toys: { name: "Bone" })
 
-    assert_equal count, 1
-    assert_equal count, Pet.joins(:toys).where(where_args).delete_all
+    assert_equal true, pets.exists?
+    assert_equal pets.count, pets.delete_all
+  end
+
+  def test_delete_all_with_joins_and_where_part_is_not_hash
+    pets = Pet.joins(:toys).where("toys.name = ?", "Bone")
+
+    assert_equal true, pets.exists?
+    assert_equal pets.count, pets.delete_all
   end
 
   def test_delete_all_with_left_joins
-    where_args = { toys: { name: "Bone" } }
-    count = Pet.left_joins(:toys).where(where_args).count
+    pets = Pet.left_joins(:toys).where(toys: { name: "Bone" })
 
-    assert_equal count, 1
-    assert_equal count, Pet.left_joins(:toys).where(where_args).delete_all
+    assert_equal true, pets.exists?
+    assert_equal pets.count, pets.delete_all
   end
 
-  def test_delete_all_with_joins_and_where_part_is_not_hash
-    where_args = ["toys.name = ?", "Bone"]
-    count = Pet.joins(:toys).where(where_args).count
+  def test_delete_all_with_includes
+    pets = Pet.includes(:toys).where(toys: { name: "Bone" })
 
-    assert_equal count, 1
-    assert_equal count, Pet.joins(:toys).where(where_args).delete_all
+    assert_equal true, pets.exists?
+    assert_equal pets.count, pets.delete_all
   end
 
   def test_increment_attribute
@@ -496,17 +500,24 @@ class PersistenceTest < ActiveRecord::TestCase
   end
 
   def test_update_all_with_joins
-    where_args = { toys: { name: "Bone" } }
-    count = Pet.left_joins(:toys).where(where_args).count
+    pets = Pet.joins(:toys).where(toys: { name: "Bone" })
 
-    assert_equal count, Pet.joins(:toys).where(where_args).update_all(name: "Bob")
+    assert_equal true, pets.exists?
+    assert_equal pets.count, pets.update_all(name: "Bob")
   end
 
   def test_update_all_with_left_joins
-    where_args = { toys: { name: "Bone" } }
-    count = Pet.left_joins(:toys).where(where_args).count
+    pets = Pet.left_joins(:toys).where(toys: { name: "Bone" })
+
+    assert_equal true, pets.exists?
+    assert_equal pets.count, pets.update_all(name: "Bob")
+  end
+
+  def test_update_all_with_includes
+    pets = Pet.includes(:toys).where(toys: { name: "Bone" })
 
-    assert_equal count, Pet.left_joins(:toys).where(where_args).update_all(name: "Bob")
+    assert_equal true, pets.exists?
+    assert_equal pets.count, pets.update_all(name: "Bob")
   end
 
   def test_update_all_with_non_standard_table_name
diff --git a/activerecord/test/cases/scoping/relation_scoping_test.rb b/activerecord/test/cases/scoping/relation_scoping_test.rb
index f3b84d88c2..116f8e83aa 100644
--- a/activerecord/test/cases/scoping/relation_scoping_test.rb
+++ b/activerecord/test/cases/scoping/relation_scoping_test.rb
@@ -240,6 +240,20 @@ class RelationScopingTest < ActiveRecord::TestCase
     assert_nil SpecialComment.current_scope
   end
 
+  def test_scoping_respects_current_class
+    Comment.unscoped do
+      assert_equal "a comment...", Comment.all.what_are_you
+      assert_equal "a special comment...", SpecialComment.all.what_are_you
+    end
+  end
+
+  def test_scoping_respects_sti_constraint
+    Comment.unscoped do
+      assert_equal comments(:greetings), Comment.find(1)
+      assert_raises(ActiveRecord::RecordNotFound) { SpecialComment.find(1) }
+    end
+  end
+
   def test_circular_joins_with_scoping_does_not_crash
     posts = Post.joins(comments: :post).scoping do
       Post.first(10)
diff --git a/activerecord/test/cases/tasks/database_tasks_test.rb b/activerecord/test/cases/tasks/database_tasks_test.rb
index 1495d2ab89..5a094ead42 100644
--- a/activerecord/test/cases/tasks/database_tasks_test.rb
+++ b/activerecord/test/cases/tasks/database_tasks_test.rb
@@ -357,8 +357,15 @@ module ActiveRecord
       ActiveRecord::Migration.expects(:verbose=).with(ActiveRecord::Migration.verbose)
       ActiveRecord::Tasks::DatabaseTasks.migrate
 
+      ENV["VERBOSE"] = ""
+      ENV["VERSION"] = ""
+      ActiveRecord::Migrator.expects(:migrate).with("custom/path", nil)
+      ActiveRecord::Migration.expects(:verbose=).with(true)
+      ActiveRecord::Migration.expects(:verbose=).with(ActiveRecord::Migration.verbose)
+      ActiveRecord::Tasks::DatabaseTasks.migrate
+
       ENV["VERBOSE"] = "yes"
-      ENV["VERSION"] = "unknown"
+      ENV["VERSION"] = "0"
       ActiveRecord::Migrator.expects(:migrate).with("custom/path", 0)
       ActiveRecord::Migration.expects(:verbose=).with(true)
       ActiveRecord::Migration.expects(:verbose=).with(ActiveRecord::Migration.verbose)
@@ -367,15 +374,47 @@ module ActiveRecord
       ENV["VERBOSE"], ENV["VERSION"] = verbose, version
     end
 
-    def test_migrate_raise_error_on_empty_version
+    def test_migrate_raise_error_on_invalid_version_format
       version = ENV["VERSION"]
-      ENV["VERSION"] = ""
+
+      ENV["VERSION"] = "unknown"
+      e = assert_raise(RuntimeError) { ActiveRecord::Tasks::DatabaseTasks.migrate }
+      assert_match(/Invalid format of target version/, e.message)
+
+      ENV["VERSION"] = "0.1.11"
+      e = assert_raise(RuntimeError) { ActiveRecord::Tasks::DatabaseTasks.migrate }
+      assert_match(/Invalid format of target version/, e.message)
+
+      ENV["VERSION"] = "1.1.11"
+      e = assert_raise(RuntimeError) { ActiveRecord::Tasks::DatabaseTasks.migrate }
+      assert_match(/Invalid format of target version/, e.message)
+
+      ENV["VERSION"] = "0 "
+      e = assert_raise(RuntimeError) { ActiveRecord::Tasks::DatabaseTasks.migrate }
+      assert_match(/Invalid format of target version/, e.message)
+
+      ENV["VERSION"] = "1."
+      e = assert_raise(RuntimeError) { ActiveRecord::Tasks::DatabaseTasks.migrate }
+      assert_match(/Invalid format of target version/, e.message)
+
+      ENV["VERSION"] = "1_"
       e = assert_raise(RuntimeError) { ActiveRecord::Tasks::DatabaseTasks.migrate }
-      assert_equal "Empty VERSION provided", e.message
+      assert_match(/Invalid format of target version/, e.message)
+
+      ENV["VERSION"] = "1_name"
+      e = assert_raise(RuntimeError) { ActiveRecord::Tasks::DatabaseTasks.migrate }
+      assert_match(/Invalid format of target version/, e.message)
     ensure
       ENV["VERSION"] = version
     end
 
+    def test_migrate_raise_error_on_failed_check_target_version
+      ActiveRecord::Tasks::DatabaseTasks.stubs(:check_target_version).raises("foo")
+
+      e = assert_raise(RuntimeError) { ActiveRecord::Tasks::DatabaseTasks.migrate }
+      assert_equal "foo", e.message
+    end
+
     def test_migrate_clears_schema_cache_afterward
       ActiveRecord::Base.expects(:clear_cache!)
       ActiveRecord::Tasks::DatabaseTasks.migrate
@@ -444,6 +483,108 @@ module ActiveRecord
     end
   end
 
+  class DatabaseTaskTargetVersionTest < ActiveRecord::TestCase
+    def test_target_version_returns_nil_if_version_does_not_exist
+      version = ENV.delete("VERSION")
+      assert_nil ActiveRecord::Tasks::DatabaseTasks.target_version
+    ensure
+      ENV["VERSION"] = version
+    end
+
+    def test_target_version_returns_nil_if_version_is_empty
+      version = ENV["VERSION"]
+
+      ENV["VERSION"] = ""
+      assert_nil ActiveRecord::Tasks::DatabaseTasks.target_version
+    ensure
+      ENV["VERSION"] = version
+    end
+
+    def test_target_version_returns_converted_to_integer_env_version_if_version_exists
+      version = ENV["VERSION"]
+
+      ENV["VERSION"] = "0"
+      assert_equal ENV["VERSION"].to_i, ActiveRecord::Tasks::DatabaseTasks.target_version
+
+      ENV["VERSION"] = "42"
+      assert_equal ENV["VERSION"].to_i, ActiveRecord::Tasks::DatabaseTasks.target_version
+
+      ENV["VERSION"] = "042"
+      assert_equal ENV["VERSION"].to_i, ActiveRecord::Tasks::DatabaseTasks.target_version
+    ensure
+      ENV["VERSION"] = version
+    end
+  end
+
+  class DatabaseTaskCheckTargetVersionTest < ActiveRecord::TestCase
+    def test_check_target_version_does_not_raise_error_on_empty_version
+      version = ENV["VERSION"]
+      ENV["VERSION"] = ""
+      assert_nothing_raised { ActiveRecord::Tasks::DatabaseTasks.check_target_version }
+    ensure
+      ENV["VERSION"] = version
+    end
+
+    def test_check_target_version_does_not_raise_error_if_version_is_not_setted
+      version = ENV.delete("VERSION")
+      assert_nothing_raised { ActiveRecord::Tasks::DatabaseTasks.check_target_version }
+    ensure
+      ENV["VERSION"] = version
+    end
+
+    def test_check_target_version_raises_error_on_invalid_version_format
+      version = ENV["VERSION"]
+
+      ENV["VERSION"] = "unknown"
+      e = assert_raise(RuntimeError) { ActiveRecord::Tasks::DatabaseTasks.check_target_version }
+      assert_match(/Invalid format of target version/, e.message)
+
+      ENV["VERSION"] = "0.1.11"
+      e = assert_raise(RuntimeError) { ActiveRecord::Tasks::DatabaseTasks.check_target_version }
+      assert_match(/Invalid format of target version/, e.message)
+
+      ENV["VERSION"] = "1.1.11"
+      e = assert_raise(RuntimeError) { ActiveRecord::Tasks::DatabaseTasks.check_target_version }
+      assert_match(/Invalid format of target version/, e.message)
+
+      ENV["VERSION"] = "0 "
+      e = assert_raise(RuntimeError) { ActiveRecord::Tasks::DatabaseTasks.check_target_version }
+      assert_match(/Invalid format of target version/, e.message)
+
+      ENV["VERSION"] = "1."
+      e = assert_raise(RuntimeError) { ActiveRecord::Tasks::DatabaseTasks.check_target_version }
+      assert_match(/Invalid format of target version/, e.message)
+
+      ENV["VERSION"] = "1_"
+      e = assert_raise(RuntimeError) { ActiveRecord::Tasks::DatabaseTasks.check_target_version }
+      assert_match(/Invalid format of target version/, e.message)
+
+      ENV["VERSION"] = "1_name"
+      e = assert_raise(RuntimeError) { ActiveRecord::Tasks::DatabaseTasks.check_target_version }
+      assert_match(/Invalid format of target version/, e.message)
+    ensure
+      ENV["VERSION"] = version
+    end
+
+    def test_check_target_version_does_not_raise_error_on_valid_version_format
+      version = ENV["VERSION"]
+
+      ENV["VERSION"] = "0"
+      assert_nothing_raised { ActiveRecord::Tasks::DatabaseTasks.check_target_version }
+
+      ENV["VERSION"] = "1"
+      assert_nothing_raised { ActiveRecord::Tasks::DatabaseTasks.check_target_version }
+
+      ENV["VERSION"] = "001"
+      assert_nothing_raised { ActiveRecord::Tasks::DatabaseTasks.check_target_version }
+
+      ENV["VERSION"] = "001_name.rb"
+      assert_nothing_raised { ActiveRecord::Tasks::DatabaseTasks.check_target_version }
+    ensure
+      ENV["VERSION"] = version
+    end
+  end
+
   class DatabaseTasksStructureDumpTest < ActiveRecord::TestCase
     include DatabaseTasksSetupper
 
diff --git a/activerecord/test/cases/transaction_isolation_test.rb b/activerecord/test/cases/transaction_isolation_test.rb
index b1ebccdcc3..eaafd13360 100644
--- a/activerecord/test/cases/transaction_isolation_test.rb
+++ b/activerecord/test/cases/transaction_isolation_test.rb
@@ -15,9 +15,7 @@ unless ActiveRecord::Base.connection.supports_transaction_isolation?
       end
     end
   end
-end
-
-if ActiveRecord::Base.connection.supports_transaction_isolation?
+else
   class TransactionIsolationTest < ActiveRecord::TestCase
     self.use_transactional_tests = false
 
diff --git a/activerecord/test/cases/transactions_test.rb b/activerecord/test/cases/transactions_test.rb
index 7fd125ab74..5c8ae4d3cb 100644
--- a/activerecord/test/cases/transactions_test.rb
+++ b/activerecord/test/cases/transactions_test.rb
@@ -954,27 +954,25 @@ class TransactionsWithTransactionalFixturesTest < ActiveRecord::TestCase
   end
 end if Topic.connection.supports_savepoints?
 
-if current_adapter?(:PostgreSQLAdapter)
+if ActiveRecord::Base.connection.supports_transaction_isolation?
   class ConcurrentTransactionTest < TransactionTest
     # This will cause transactions to overlap and fail unless they are performed on
     # separate database connections.
-    unless in_memory_db?
-      def test_transaction_per_thread
-        threads = 3.times.map do
-          Thread.new do
-            Topic.transaction do
-              topic = Topic.find(1)
-              topic.approved = !topic.approved?
-              assert topic.save!
-              topic.approved = !topic.approved?
-              assert topic.save!
-            end
-            Topic.connection.close
+    def test_transaction_per_thread
+      threads = 3.times.map do
+        Thread.new do
+          Topic.transaction do
+            topic = Topic.find(1)
+            topic.approved = !topic.approved?
+            assert topic.save!
+            topic.approved = !topic.approved?
+            assert topic.save!
           end
+          Topic.connection.close
         end
-
-        threads.each(&:join)
       end
+
+      threads.each(&:join)
     end
 
     # Test for dirty reads among simultaneous transactions.
diff --git a/activerecord/test/models/comment.rb b/activerecord/test/models/comment.rb
index 740aa593ac..5ab433f2d9 100644
--- a/activerecord/test/models/comment.rb
+++ b/activerecord/test/models/comment.rb
@@ -60,6 +60,10 @@ end
 
 class SpecialComment < Comment
   default_scope { where(deleted_at: nil) }
+
+  def self.what_are_you
+    "a special comment..."
+  end
 end
 
 class SubSpecialComment < SpecialComment
diff --git a/activerecord/test/schema/schema.rb b/activerecord/test/schema/schema.rb
index 8f872c38ba..a4505a4892 100644
--- a/activerecord/test/schema/schema.rb
+++ b/activerecord/test/schema/schema.rb
@@ -191,6 +191,7 @@ ActiveRecord::Schema.define do
     t.string :resource_id
     t.string :resource_type
     t.integer :developer_id
+    t.datetime :updated_at
     t.datetime :deleted_at
     t.integer :comments
   end