Store newly-uploaded files on save rather than assignment

22 files changed, 1049 insertions, 679 deletions

diff --git a/activestorage/CHANGELOG.md b/activestorage/CHANGELOG.md
index 4aa551781b..0e9c2b5619 100644
--- a/activestorage/CHANGELOG.md
+++ b/activestorage/CHANGELOG.md
@@ -1,3 +1,17 @@
+*   Uploaded files assigned to a record are persisted to storage when the record
+    is saved instead of immediately.
+
+    In Rails 5.2, the following causes an uploaded file in `params[:avatar]` to
+    be stored:
+
+    ```ruby
+    @user.avatar = params[:avatar]
+    ```
+
+    In Rails 6, the uploaded file is stored when `@user` is successfully saved.
+
+    *George Claghorn*
+
 *   Add the ability to reflect on defined attachments using the existing
     ActiveRecord reflection mechanism.
 
diff --git a/activestorage/app/models/active_storage/attachment.rb b/activestorage/app/models/active_storage/attachment.rb
index c59877a9a5..bb80799044 100644
--- a/activestorage/app/models/active_storage/attachment.rb
+++ b/activestorage/app/models/active_storage/attachment.rb
@@ -15,17 +15,18 @@ class ActiveStorage::Attachment < ActiveRecord::Base
   delegate_missing_to :blob
 
   after_create_commit :analyze_blob_later, :identify_blob
+  after_destroy_commit :purge_dependent_blob_later
 
-  # Synchronously purges the blob (deletes it from the configured service) and destroys the attachment.
+  # Synchronously purges the blob (deletes it from the configured service) and deletes the attachment.
   def purge
     blob.purge
-    destroy
+    delete
   end
 
-  # Destroys the attachment and asynchronously purges the blob (deletes it from the configured service).
+  # Deletes the attachment and queues a background job to purge the blob (delete it from the configured service).
   def purge_later
     blob.purge_later
-    destroy
+    delete
   end
 
   private
@@ -36,4 +37,13 @@ class ActiveStorage::Attachment < ActiveRecord::Base
     def analyze_blob_later
       blob.analyze_later unless blob.analyzed?
     end
+
+    def purge_dependent_blob_later
+      blob.purge_later if dependent == :purge_later
+    end
+
+
+    def dependent
+      record.attachment_reflections[name]&.options[:dependent]
+    end
 end
diff --git a/activestorage/app/models/active_storage/blob.rb b/activestorage/app/models/active_storage/blob.rb
index 73029f21a1..86f3dba524 100644
--- a/activestorage/app/models/active_storage/blob.rb
+++ b/activestorage/app/models/active_storage/blob.rb
@@ -48,15 +48,17 @@ class ActiveStorage::Blob < ActiveRecord::Base
     # Returns a new, unsaved blob instance after the +io+ has been uploaded to the service.
     # When providing a content type, pass <tt>identify: false</tt> to bypass automatic content type inference.
     def build_after_upload(io:, filename:, content_type: nil, metadata: nil, identify: true)
-      new.tap do |blob|
-        blob.filename     = filename
-        blob.content_type = content_type
-        blob.metadata     = metadata
-
+      new(filename: filename, content_type: content_type, metadata: metadata).tap do |blob|
         blob.upload(io, identify: identify)
       end
     end
 
+    def build_after_unfurling(io:, filename:, content_type: nil, metadata: nil, identify: true) #:nodoc:
+      new(filename: filename, content_type: content_type, metadata: metadata).tap do |blob|
+        blob.unfurl(io, identify: identify)
+      end
+    end
+
     # Returns a saved blob instance after the +io+ has been uploaded to the service. Note, the blob is first built,
     # then the +io+ is uploaded, then the blob is saved. This is done this way to avoid uploading (which may take
     # time), while having an open database transaction.
@@ -152,12 +154,19 @@ class ActiveStorage::Blob < ActiveRecord::Base
   # Normally, you do not have to call this method directly at all. Use the factory class methods of +build_after_upload+
   # and +create_after_upload!+.
   def upload(io, identify: true)
+    unfurl io, identify: identify
+    upload_without_unfurling io
+  end
+
+  def unfurl(io, identify: true) #:nodoc:
     self.checksum     = compute_checksum_in_chunks(io)
     self.content_type = extract_content_type(io) if content_type.nil? || identify
     self.byte_size    = io.size
     self.identified   = true
+  end
 
-    service.upload(key, io, checksum: checksum)
+  def upload_without_unfurling(io) #:nodoc:
+    service.upload key, io, checksum: checksum
   end
 
   # Downloads the file associated with this blob. If no block is given, the entire file is read into memory and returned.
diff --git a/activestorage/lib/active_storage/attached.rb b/activestorage/lib/active_storage/attached.rb
index c08fd56652..1b53818581 100644
--- a/activestorage/lib/active_storage/attached.rb
+++ b/activestorage/lib/active_storage/attached.rb
@@ -15,6 +15,10 @@ module ActiveStorage
     end
 
     private
+      def change
+        record.attachment_changes[name]
+      end
+
       def create_blob_from(attachable)
         case attachable
         when ActiveStorage::Blob
@@ -35,6 +39,7 @@ module ActiveStorage
   end
 end
 
+require "active_storage/attached/model"
 require "active_storage/attached/one"
 require "active_storage/attached/many"
-require "active_storage/attached/macros"
+require "active_storage/attached/changes"
diff --git a/activestorage/lib/active_storage/attached/changes.rb b/activestorage/lib/active_storage/attached/changes.rb
new file mode 100644
index 0000000000..1db3906a63
--- /dev/null
+++ b/activestorage/lib/active_storage/attached/changes.rb
@@ -0,0 +1,16 @@
+# frozen_string_literal: true
+
+module ActiveStorage
+  module Attached::Changes #:nodoc:
+    extend ActiveSupport::Autoload
+
+    eager_autoload do
+      autoload :CreateOne
+      autoload :CreateMany
+      autoload :CreateOneOfMany
+
+      autoload :DeleteOne
+      autoload :DeleteMany
+    end
+  end
+end
diff --git a/activestorage/lib/active_storage/attached/changes/create_many.rb b/activestorage/lib/active_storage/attached/changes/create_many.rb
new file mode 100644
index 0000000000..3f7ca6a25f
--- /dev/null
+++ b/activestorage/lib/active_storage/attached/changes/create_many.rb
@@ -0,0 +1,32 @@
+# frozen_string_literal: true
+
+module ActiveStorage
+  class Attached::Changes::CreateMany #:nodoc:
+    attr_reader :name, :record, :attachables
+
+    def initialize(name, record, attachables)
+      @name, @record, @attachables = name, record, Array(attachables)
+    end
+
+    def attachments
+      @attachments ||= subchanges.collect(&:attachment)
+    end
+
+    def upload
+      subchanges.each(&:upload)
+    end
+
+    def save
+      record.public_send("#{name}_attachments=", attachments)
+    end
+
+    private
+      def subchanges
+        @subchanges ||= attachables.collect { |attachable| build_subchange_from(attachable) }
+      end
+
+      def build_subchange_from(attachable)
+        ActiveStorage::Attached::Changes::CreateOneOfMany.new(name, record, attachable)
+      end
+  end
+end
diff --git a/activestorage/lib/active_storage/attached/changes/create_one.rb b/activestorage/lib/active_storage/attached/changes/create_one.rb
new file mode 100644
index 0000000000..bb59a651ba
--- /dev/null
+++ b/activestorage/lib/active_storage/attached/changes/create_one.rb
@@ -0,0 +1,65 @@
+# frozen_string_literal: true
+
+module ActiveStorage
+  class Attached::Changes::CreateOne #:nodoc:
+    attr_reader :name, :record, :attachable
+
+    def initialize(name, record, attachable)
+      @name, @record, @attachable = name, record, attachable
+    end
+
+    def attachment
+      @attachment ||= find_or_build_attachment
+    end
+
+    def blob
+      @blob ||= find_or_build_blob
+    end
+
+    def upload
+      case attachable
+      when ActionDispatch::Http::UploadedFile, Rack::Test::UploadedFile
+        blob.upload_without_unfurling(attachable.open)
+      when Hash
+        blob.upload_without_unfurling(attachable.fetch(:io))
+      end
+    end
+
+    def save
+      record.public_send("#{name}_attachment=", attachment)
+    end
+
+    private
+      def find_or_build_attachment
+        find_attachment || build_attachment
+      end
+
+      def find_attachment
+        if record.public_send("#{name}_blob") == blob
+          record.public_send("#{name}_attachment")
+        end
+      end
+
+      def build_attachment
+        ActiveStorage::Attachment.new(record: record, name: name, blob: blob)
+      end
+
+      def find_or_build_blob
+        case attachable
+        when ActiveStorage::Blob
+          attachable
+        when ActionDispatch::Http::UploadedFile, Rack::Test::UploadedFile
+          ActiveStorage::Blob.build_after_unfurling \
+            io: attachable.open,
+            filename: attachable.original_filename,
+            content_type: attachable.content_type
+        when Hash
+          ActiveStorage::Blob.build_after_unfurling(attachable)
+        when String
+          ActiveStorage::Blob.find_signed(attachable)
+        else
+          raise "Could not find or build blob: expected attachable, got #{attachable.inspect}"
+        end
+      end
+  end
+end
diff --git a/activestorage/lib/active_storage/attached/changes/create_one_of_many.rb b/activestorage/lib/active_storage/attached/changes/create_one_of_many.rb
new file mode 100644
index 0000000000..7268e87316
--- /dev/null
+++ b/activestorage/lib/active_storage/attached/changes/create_one_of_many.rb
@@ -0,0 +1,10 @@
+# frozen_string_literal: true
+
+module ActiveStorage
+  class Attached::Changes::CreateOneOfMany < Attached::Changes::CreateOne #:nodoc:
+    private
+      def find_attachment
+        record.public_send("#{name}_attachments").detect { |attachment| attachment.blob_id == blob.id }
+      end
+  end
+end
diff --git a/activestorage/lib/active_storage/attached/changes/delete_many.rb b/activestorage/lib/active_storage/attached/changes/delete_many.rb
new file mode 100644
index 0000000000..5c7fe385de
--- /dev/null
+++ b/activestorage/lib/active_storage/attached/changes/delete_many.rb
@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+module ActiveStorage
+  class Attached::Changes::DeleteMany #:nodoc:
+    attr_reader :name, :record
+
+    def initialize(name, record)
+      @name, @record = name, record
+    end
+
+    def attachments
+      ActiveStorage::Attachment.none
+    end
+
+    def save
+      record.public_send("#{name}_attachments=", [])
+    end
+  end
+end
diff --git a/activestorage/lib/active_storage/attached/changes/delete_one.rb b/activestorage/lib/active_storage/attached/changes/delete_one.rb
new file mode 100644
index 0000000000..2f7d356613
--- /dev/null
+++ b/activestorage/lib/active_storage/attached/changes/delete_one.rb
@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+module ActiveStorage
+  class Attached::Changes::DeleteOne #:nodoc:
+    attr_reader :name, :record
+
+    def initialize(name, record)
+      @name, @record = name, record
+    end
+
+    def attachment
+      nil
+    end
+
+    def save
+      record.public_send("#{name}_attachment=", nil)
+    end
+  end
+end
diff --git a/activestorage/lib/active_storage/attached/macros.rb b/activestorage/lib/active_storage/attached/macros.rb
deleted file mode 100644
index 6ad9fc43d7..0000000000
--- a/activestorage/lib/active_storage/attached/macros.rb
+++ /dev/null
@@ -1,122 +0,0 @@
-# frozen_string_literal: true
-
-module ActiveStorage
-  # Provides the class-level DSL for declaring that an Active Record model has attached blobs.
-  module Attached::Macros
-    # Specifies the relation between a single attachment and the model.
-    #
-    #   class User < ActiveRecord::Base
-    #     has_one_attached :avatar
-    #   end
-    #
-    # There is no column defined on the model side, Active Storage takes
-    # care of the mapping between your records and the attachment.
-    #
-    # To avoid N+1 queries, you can include the attached blobs in your query like so:
-    #
-    #   User.with_attached_avatar
-    #
-    # Under the covers, this relationship is implemented as a +has_one+ association to a
-    # ActiveStorage::Attachment record and a +has_one-through+ association to a
-    # ActiveStorage::Blob record. These associations are available as +avatar_attachment+
-    # and +avatar_blob+. But you shouldn't need to work with these associations directly in
-    # most circumstances.
-    #
-    # The system has been designed to having you go through the ActiveStorage::Attached::One
-    # proxy that provides the dynamic proxy to the associations and factory methods, like +attach+.
-    #
-    # If the +:dependent+ option isn't set, the attachment will be purged
-    # (i.e. destroyed) whenever the record is destroyed.
-    def has_one_attached(name, dependent: :purge_later)
-      generated_association_methods.class_eval <<-CODE, __FILE__, __LINE__ + 1
-        def #{name}
-          @active_storage_attached_#{name} ||= ActiveStorage::Attached::One.new("#{name}", self, dependent: #{dependent == :purge_later ? ":purge_later" : "false"})
-        end
-
-        def #{name}=(attachable)
-          #{name}.attach(attachable)
-        end
-      CODE
-
-      has_one :"#{name}_attachment", -> { where(name: name) }, class_name: "ActiveStorage::Attachment", as: :record, inverse_of: :record, dependent: false
-      has_one :"#{name}_blob", through: :"#{name}_attachment", class_name: "ActiveStorage::Blob", source: :blob
-
-      scope :"with_attached_#{name}", -> { includes("#{name}_attachment": :blob) }
-
-      if dependent == :purge_later
-        after_destroy_commit { public_send(name).purge_later }
-      else
-        before_destroy { public_send(name).detach }
-      end
-
-      ActiveRecord::Reflection.add_attachment_reflection(
-        self,
-        name,
-        ActiveRecord::Reflection.create(:has_one_attached, name, nil, { dependent: dependent }, self)
-      )
-    end
-
-    # Specifies the relation between multiple attachments and the model.
-    #
-    #   class Gallery < ActiveRecord::Base
-    #     has_many_attached :photos
-    #   end
-    #
-    # There are no columns defined on the model side, Active Storage takes
-    # care of the mapping between your records and the attachments.
-    #
-    # To avoid N+1 queries, you can include the attached blobs in your query like so:
-    #
-    #   Gallery.where(user: Current.user).with_attached_photos
-    #
-    # Under the covers, this relationship is implemented as a +has_many+ association to a
-    # ActiveStorage::Attachment record and a +has_many-through+ association to a
-    # ActiveStorage::Blob record. These associations are available as +photos_attachments+
-    # and +photos_blobs+. But you shouldn't need to work with these associations directly in
-    # most circumstances.
-    #
-    # The system has been designed to having you go through the ActiveStorage::Attached::Many
-    # proxy that provides the dynamic proxy to the associations and factory methods, like +#attach+.
-    #
-    # If the +:dependent+ option isn't set, all the attachments will be purged
-    # (i.e. destroyed) whenever the record is destroyed.
-    def has_many_attached(name, dependent: :purge_later)
-      generated_association_methods.class_eval <<-CODE, __FILE__, __LINE__ + 1
-        def #{name}
-          @active_storage_attached_#{name} ||= ActiveStorage::Attached::Many.new("#{name}", self, dependent: #{dependent == :purge_later ? ":purge_later" : "false"})
-        end
-
-        def #{name}=(attachables)
-          #{name}.attach(attachables)
-        end
-      CODE
-
-      has_many :"#{name}_attachments", -> { where(name: name) }, as: :record, class_name: "ActiveStorage::Attachment", inverse_of: :record, dependent: false do
-        def purge
-          each(&:purge)
-          reset
-        end
-
-        def purge_later
-          each(&:purge_later)
-          reset
-        end
-      end
-      has_many :"#{name}_blobs", through: :"#{name}_attachments", class_name: "ActiveStorage::Blob", source: :blob
-
-      scope :"with_attached_#{name}", -> { includes("#{name}_attachments": :blob) }
-
-      if dependent == :purge_later
-        after_destroy_commit { public_send(name).purge_later }
-      else
-        before_destroy { public_send(name).detach }
-      end
-
-      ActiveRecord::Reflection.add_attachment_reflection(
-        self,
-        name,
-        ActiveRecord::Reflection.create(:has_many_attached, name, nil, { dependent: dependent }, self)
-      )
-    end
-  end
-end
diff --git a/activestorage/lib/active_storage/attached/many.rb b/activestorage/lib/active_storage/attached/many.rb
index d61acb6fad..204d6604c8 100644
--- a/activestorage/lib/active_storage/attached/many.rb
+++ b/activestorage/lib/active_storage/attached/many.rb
@@ -9,7 +9,7 @@ module ActiveStorage
     #
     # All methods called on this proxy object that aren't listed here will automatically be delegated to +attachments+.
     def attachments
-      record.public_send("#{name}_attachments")
+      change.present? ? change.attachments : record.public_send("#{name}_attachments")
     end
 
     # Associates one or several attachments with the current record, saving them to the database.
@@ -50,7 +50,6 @@ module ActiveStorage
     # Directly purges each associated attachment (i.e. destroys the blobs and
     # attachments and deletes the files on the service).
 
-
     ##
     # :method: purge_later
     #
diff --git a/activestorage/lib/active_storage/attached/model.rb b/activestorage/lib/active_storage/attached/model.rb
new file mode 100644
index 0000000000..287c7a9253
--- /dev/null
+++ b/activestorage/lib/active_storage/attached/model.rb
@@ -0,0 +1,150 @@
+# frozen_string_literal: true
+
+module ActiveStorage
+  # Provides the class-level DSL for declaring an Active Record model's attachments.
+  module Attached::Model
+    extend ActiveSupport::Concern
+
+    class_methods do
+      # Specifies the relation between a single attachment and the model.
+      #
+      #   class User < ActiveRecord::Base
+      #     has_one_attached :avatar
+      #   end
+      #
+      # There is no column defined on the model side, Active Storage takes
+      # care of the mapping between your records and the attachment.
+      #
+      # To avoid N+1 queries, you can include the attached blobs in your query like so:
+      #
+      #   User.with_attached_avatar
+      #
+      # Under the covers, this relationship is implemented as a +has_one+ association to a
+      # ActiveStorage::Attachment record and a +has_one-through+ association to a
+      # ActiveStorage::Blob record. These associations are available as +avatar_attachment+
+      # and +avatar_blob+. But you shouldn't need to work with these associations directly in
+      # most circumstances.
+      #
+      # The system has been designed to having you go through the ActiveStorage::Attached::One
+      # proxy that provides the dynamic proxy to the associations and factory methods, like +attach+.
+      #
+      # If the +:dependent+ option isn't set, the attachment will be purged
+      # (i.e. destroyed) whenever the record is destroyed.
+      def has_one_attached(name, dependent: :purge_later)
+        generated_association_methods.class_eval <<-CODE, __FILE__, __LINE__ + 1
+          def #{name}
+            @active_storage_attached_#{name} ||= ActiveStorage::Attached::One.new("#{name}", self, dependent: #{dependent == :purge_later ? ":purge_later" : "false"})
+          end
+
+          def #{name}=(attachable)
+            attachment_changes["#{name}"] =
+              if attachable.nil?
+                ActiveStorage::Attached::Changes::DeleteOne.new("#{name}", self)
+              else
+                ActiveStorage::Attached::Changes::CreateOne.new("#{name}", self, attachable)
+              end
+          end
+        CODE
+
+        has_one :"#{name}_attachment", -> { where(name: name) }, class_name: "ActiveStorage::Attachment", as: :record, inverse_of: :record, dependent: :destroy
+        has_one :"#{name}_blob", through: :"#{name}_attachment", class_name: "ActiveStorage::Blob", source: :blob
+
+        scope :"with_attached_#{name}", -> { includes("#{name}_attachment": :blob) }
+
+        after_save { attachment_changes[name.to_s]&.save }
+
+        ActiveRecord::Reflection.add_attachment_reflection(
+          self,
+          name,
+          ActiveRecord::Reflection.create(:has_one_attached, name, nil, { dependent: dependent }, self)
+        )
+      end
+
+      # Specifies the relation between multiple attachments and the model.
+      #
+      #   class Gallery < ActiveRecord::Base
+      #     has_many_attached :photos
+      #   end
+      #
+      # There are no columns defined on the model side, Active Storage takes
+      # care of the mapping between your records and the attachments.
+      #
+      # To avoid N+1 queries, you can include the attached blobs in your query like so:
+      #
+      #   Gallery.where(user: Current.user).with_attached_photos
+      #
+      # Under the covers, this relationship is implemented as a +has_many+ association to a
+      # ActiveStorage::Attachment record and a +has_many-through+ association to a
+      # ActiveStorage::Blob record. These associations are available as +photos_attachments+
+      # and +photos_blobs+. But you shouldn't need to work with these associations directly in
+      # most circumstances.
+      #
+      # The system has been designed to having you go through the ActiveStorage::Attached::Many
+      # proxy that provides the dynamic proxy to the associations and factory methods, like +#attach+.
+      #
+      # If the +:dependent+ option isn't set, all the attachments will be purged
+      # (i.e. destroyed) whenever the record is destroyed.
+      def has_many_attached(name, dependent: :purge_later)
+        generated_association_methods.class_eval <<-CODE, __FILE__, __LINE__ + 1
+          def #{name}
+            @active_storage_attached_#{name} ||= ActiveStorage::Attached::Many.new("#{name}", self, dependent: #{dependent == :purge_later ? ":purge_later" : "false"})
+          end
+
+          def #{name}=(attachables)
+            attachment_changes["#{name}"] =
+              if attachables.nil? || Array(attachables).none?
+                ActiveStorage::Attached::Changes::DeleteMany.new("#{name}", self)
+              else
+                ActiveStorage::Attached::Changes::CreateMany.new("#{name}", self, attachables)
+              end
+          end
+        CODE
+
+        has_many :"#{name}_attachments", -> { where(name: name) }, as: :record, class_name: "ActiveStorage::Attachment", inverse_of: :record, dependent: :destroy do
+          def purge
+            each(&:purge)
+            reset
+          end
+
+          def purge_later
+            each(&:purge_later)
+            reset
+          end
+        end
+        has_many :"#{name}_blobs", through: :"#{name}_attachments", class_name: "ActiveStorage::Blob", source: :blob
+
+        scope :"with_attached_#{name}", -> { includes("#{name}_attachments": :blob) }
+
+        after_save { attachment_changes[name.to_s]&.save }
+
+        ActiveRecord::Reflection.add_attachment_reflection(
+          self,
+          name,
+          ActiveRecord::Reflection.create(:has_many_attached, name, nil, { dependent: dependent }, self)
+        )
+      end
+    end
+
+    def committed!(*) #:nodoc:
+      unless destroyed?
+        upload_attachment_changes
+        clear_attachment_changes
+      end
+
+      super
+    end
+
+    def attachment_changes #:nodoc:
+      @attachment_changes ||= {}
+    end
+
+    private
+      def upload_attachment_changes
+        attachment_changes.each_value { |change| change.try(:upload) }
+      end
+
+      def clear_attachment_changes
+        @attachment_changes = {}
+      end
+  end
+end
diff --git a/activestorage/lib/active_storage/attached/one.rb b/activestorage/lib/active_storage/attached/one.rb
index f992cb5f84..960ff99e63 100644
--- a/activestorage/lib/active_storage/attached/one.rb
+++ b/activestorage/lib/active_storage/attached/one.rb
@@ -10,11 +10,11 @@ module ActiveStorage
     # You don't have to call this method to access the attachment's methods as
     # they are all available at the model level.
     def attachment
-      record.public_send("#{name}_attachment")
+      change.present? ? change.attachment : record.public_send("#{name}_attachment")
     end
 
     def blank?
-      attachment.blank?
+      !attached?
     end
 
     # Associates a given attachment with the current record, saving it to the database.
@@ -24,16 +24,10 @@ module ActiveStorage
     #   person.avatar.attach(io: File.open("/path/to/face.jpg"), filename: "face.jpg", content_type: "image/jpg")
     #   person.avatar.attach(avatar_blob) # ActiveStorage::Blob object
     def attach(attachable)
-      blob_was = blob if attached?
-      blob = create_blob_from(attachable)
+      new_blob = create_blob_from(attachable)
 
-      unless blob == blob_was
-        transaction do
-          detach
-          write_attachment build_attachment(blob: blob)
-        end
-
-        blob_was.purge_later if blob_was && dependent == :purge_later
+      if !attached? || new_blob != blob
+        write_attachment build_attachment(blob: new_blob)
       end
     end
 
@@ -69,6 +63,7 @@ module ActiveStorage
     def purge_later
       if attached?
         attachment.purge_later
+        write_attachment nil
       end
     end
 
@@ -76,7 +71,7 @@ module ActiveStorage
       delegate :transaction, to: :record
 
       def build_attachment(blob:)
-        ActiveStorage::Attachment.new(record: record, name: name, blob: blob)
+        Attachment.new(record: record, name: name, blob: blob)
       end
 
       def write_attachment(attachment)
diff --git a/activestorage/lib/active_storage/engine.rb b/activestorage/lib/active_storage/engine.rb
index 93c5c55b95..9d6a27eabe 100644
--- a/activestorage/lib/active_storage/engine.rb
+++ b/activestorage/lib/active_storage/engine.rb
@@ -62,7 +62,7 @@ module ActiveStorage
       require "active_storage/attached"
 
       ActiveSupport.on_load(:active_record) do
-        extend ActiveStorage::Attached::Macros
+        include ActiveStorage::Attached::Model
       end
     end
 
diff --git a/activestorage/test/models/attached/many_test.rb b/activestorage/test/models/attached/many_test.rb
new file mode 100644
index 0000000000..ff2d29de11
--- /dev/null
+++ b/activestorage/test/models/attached/many_test.rb
@@ -0,0 +1,335 @@
+# frozen_string_literal: true
+
+require "test_helper"
+require "database/setup"
+
+class ActiveStorage::ManyAttachedTest < ActiveSupport::TestCase
+  include ActiveJob::TestHelper
+
+  setup do
+    @user = User.create!(name: "Josh")
+  end
+
+  teardown { ActiveStorage::Blob.all.each(&:purge) }
+
+  test "attaching existing blobs to an existing record" do
+    @user.highlights.attach create_blob(filename: "funky.jpg"), create_blob(filename: "town.jpg")
+    assert_equal "funky.jpg", @user.highlights.first.filename.to_s
+    assert_equal "town.jpg", @user.highlights.second.filename.to_s
+  end
+
+  test "attaching existing blobs from signed IDs to an existing record" do
+    @user.highlights.attach create_blob(filename: "funky.jpg").signed_id, create_blob(filename: "town.jpg").signed_id
+    assert_equal "funky.jpg", @user.highlights.first.filename.to_s
+    assert_equal "town.jpg", @user.highlights.second.filename.to_s
+  end
+
+  test "attaching new blobs from Hashes to an existing record" do
+    @user.highlights.attach(
+      { io: StringIO.new("STUFF"), filename: "funky.jpg", content_type: "image/jpg" },
+      { io: StringIO.new("THINGS"), filename: "town.jpg", content_type: "image/jpeg" })
+
+    assert_equal "funky.jpg", @user.highlights.first.filename.to_s
+    assert_equal "town.jpg", @user.highlights.second.filename.to_s
+  end
+
+  test "attaching new blobs from uploaded files to an existing record" do
+    @user.highlights.attach fixture_file_upload("racecar.jpg"), fixture_file_upload("video.mp4")
+    assert_equal "racecar.jpg", @user.highlights.first.filename.to_s
+    assert_equal "video.mp4", @user.highlights.second.filename.to_s
+  end
+
+  test "updating an existing record to attach existing blobs" do
+    @user.update! highlights: [ create_file_blob(filename: "racecar.jpg"), create_file_blob(filename: "video.mp4") ]
+    assert_equal "racecar.jpg", @user.highlights.first.filename.to_s
+    assert_equal "video.mp4", @user.highlights.second.filename.to_s
+  end
+
+  test "updating an existing record to attach existing blobs from signed IDs" do
+    @user.update! highlights: [ create_blob(filename: "funky.jpg").signed_id, create_blob(filename: "town.jpg").signed_id ]
+    assert_equal "funky.jpg", @user.highlights.first.filename.to_s
+    assert_equal "town.jpg", @user.highlights.second.filename.to_s
+  end
+
+  test "successfully updating an existing record to attach new blobs from uploaded files" do
+    @user.highlights = [ fixture_file_upload("racecar.jpg"), fixture_file_upload("video.mp4") ]
+    assert_equal "racecar.jpg", @user.highlights.first.filename.to_s
+    assert_equal "video.mp4", @user.highlights.second.filename.to_s
+    assert_not ActiveStorage::Blob.service.exist?(@user.highlights.first.key)
+    assert_not ActiveStorage::Blob.service.exist?(@user.highlights.second.key)
+
+    @user.save!
+    assert ActiveStorage::Blob.service.exist?(@user.highlights.first.key)
+    assert ActiveStorage::Blob.service.exist?(@user.highlights.second.key)
+  end
+
+  test "unsuccessfully updating an existing record to attach new blobs from uploaded files" do
+    assert_not @user.update(name: "", highlights: [ fixture_file_upload("racecar.jpg"), fixture_file_upload("video.mp4") ])
+    assert_equal "racecar.jpg", @user.highlights.first.filename.to_s
+    assert_equal "video.mp4", @user.highlights.second.filename.to_s
+    assert_not ActiveStorage::Blob.service.exist?(@user.highlights.first.key)
+    assert_not ActiveStorage::Blob.service.exist?(@user.highlights.second.key)
+  end
+
+  test "successfully updating an existing record to replace existing, dependent attachments" do
+    [ create_blob(filename: "funky.jpg"), create_blob(filename: "town.jpg") ].tap do |old_blobs|
+      @user.highlights.attach old_blobs
+
+      perform_enqueued_jobs do
+        @user.update! highlights: [ create_blob(filename: "whenever.jpg"), create_blob(filename: "wherever.jpg") ]
+      end
+
+      assert_equal "whenever.jpg", @user.highlights.first.filename.to_s
+      assert_equal "wherever.jpg", @user.highlights.second.filename.to_s
+      assert_not ActiveStorage::Blob.exists?(old_blobs.first.id)
+      assert_not ActiveStorage::Blob.exists?(old_blobs.second.id)
+      assert_not ActiveStorage::Blob.service.exist?(old_blobs.first.key)
+      assert_not ActiveStorage::Blob.service.exist?(old_blobs.second.key)
+    end
+  end
+
+  test "successfully updating an existing record to replace existing, independent attachments" do
+    @user.vlogs.attach create_blob(filename: "funky.mp4"), create_blob(filename: "town.mp4")
+
+    assert_no_enqueued_jobs only: ActiveStorage::PurgeJob do
+      @user.update! vlogs: [ create_blob(filename: "whenever.mp4"), create_blob(filename: "wherever.mp4") ]
+    end
+
+    assert_equal "whenever.mp4", @user.vlogs.first.filename.to_s
+    assert_equal "wherever.mp4", @user.vlogs.second.filename.to_s
+  end
+
+  test "unsuccessfully updating an existing record to replace existing attachments" do
+    @user.highlights.attach create_blob(filename: "funky.jpg"), create_blob(filename: "town.jpg")
+
+    assert_no_enqueued_jobs do
+      assert_not @user.update(name: "", highlights: [ fixture_file_upload("racecar.jpg"), fixture_file_upload("video.mp4") ])
+    end
+
+    assert_equal "racecar.jpg", @user.highlights.first.filename.to_s
+    assert_equal "video.mp4", @user.highlights.second.filename.to_s
+    assert_not ActiveStorage::Blob.service.exist?(@user.highlights.first.key)
+    assert_not ActiveStorage::Blob.service.exist?(@user.highlights.second.key)
+  end
+
+  test "updating an existing record to attach one new blob and one previously-attached blob" do
+    [ create_blob(filename: "funky.jpg"), create_blob(filename: "town.jpg") ].tap do |blobs|
+      @user.highlights.attach blobs.first
+
+      perform_enqueued_jobs do
+        assert_no_changes -> { @user.highlights_attachments.first.id } do
+          @user.update! highlights: blobs
+        end
+      end
+
+      assert_equal "funky.jpg", @user.highlights.first.filename.to_s
+      assert_equal "town.jpg", @user.highlights.second.filename.to_s
+      assert ActiveStorage::Blob.service.exist?(@user.highlights.first.key)
+    end
+  end
+
+  test "successfully updating an existing record to remove dependent attachments" do
+    [ create_blob(filename: "funky.jpg"), create_blob(filename: "town.jpg") ].tap do |blobs|
+      @user.highlights.attach blobs
+
+      perform_enqueued_jobs do
+        @user.update! highlights: []
+      end
+
+      assert_not @user.highlights.attached?
+      assert_not ActiveStorage::Blob.service.exist?(blobs.first.key)
+      assert_not ActiveStorage::Blob.service.exist?(blobs.second.key)
+    end
+  end
+
+  test "successfully updating an existing record to remove independent attachments" do
+    [ create_blob(filename: "funky.mp4"), create_blob(filename: "town.mp4") ].tap do |blobs|
+      @user.vlogs.attach blobs
+
+      assert_no_enqueued_jobs only: ActiveStorage::PurgeJob do
+        @user.update! vlogs: []
+      end
+
+      assert_not @user.vlogs.attached?
+      assert ActiveStorage::Blob.service.exist?(blobs.first.key)
+      assert ActiveStorage::Blob.service.exist?(blobs.second.key)
+    end
+  end
+
+  test "attaching existing blobs to a new record" do
+    User.new(name: "Jason").tap do |user|
+      user.highlights.attach create_blob(filename: "funky.jpg"), create_blob(filename: "town.jpg")
+      assert user.new_record?
+      assert_equal "funky.jpg", user.highlights.first.filename.to_s
+      assert_equal "town.jpg", user.highlights.second.filename.to_s
+
+      user.save!
+      assert_equal "funky.jpg", user.highlights.first.filename.to_s
+      assert_equal "town.jpg", user.highlights.second.filename.to_s
+    end
+  end
+
+  test "attaching an existing blob from a signed ID to a new record" do
+    User.new(name: "Jason").tap do |user|
+      user.avatar.attach create_blob(filename: "funky.jpg").signed_id
+      assert user.new_record?
+      assert_equal "funky.jpg", user.avatar.filename.to_s
+
+      user.save!
+      assert_equal "funky.jpg", user.reload.avatar.filename.to_s
+    end
+  end
+
+  test "attaching new blob from Hashes to a new record" do
+    User.new(name: "Jason").tap do |user|
+      user.highlights.attach(
+        { io: StringIO.new("STUFF"), filename: "funky.jpg", content_type: "image/jpg" },
+        { io: StringIO.new("THINGS"), filename: "town.jpg", content_type: "image/jpg" })
+
+      assert user.new_record?
+      assert user.highlights.first.new_record?
+      assert user.highlights.second.new_record?
+      assert_not user.highlights.first.blob.new_record?
+      assert_not user.highlights.second.blob.new_record?
+      assert_equal "funky.jpg", user.highlights.first.filename.to_s
+      assert_equal "town.jpg", user.highlights.second.filename.to_s
+      assert ActiveStorage::Blob.service.exist?(user.highlights.first.key)
+      assert ActiveStorage::Blob.service.exist?(user.highlights.second.key)
+
+      user.save!
+      assert_equal "funky.jpg", user.reload.highlights.first.filename.to_s
+      assert_equal "town.jpg", user.highlights.second.filename.to_s
+    end
+  end
+
+  test "attaching new blobs from uploaded files to a new record" do
+    User.new(name: "Jason").tap do |user|
+      user.highlights.attach fixture_file_upload("racecar.jpg"), fixture_file_upload("video.mp4")
+      assert user.new_record?
+      assert user.highlights.first.new_record?
+      assert user.highlights.second.new_record?
+      assert_not user.highlights.first.blob.new_record?
+      assert_not user.highlights.second.blob.new_record?
+      assert_equal "racecar.jpg", user.highlights.first.filename.to_s
+      assert_equal "video.mp4", user.highlights.second.filename.to_s
+      assert ActiveStorage::Blob.service.exist?(user.highlights.first.key)
+      assert ActiveStorage::Blob.service.exist?(user.highlights.second.key)
+
+      user.save!
+      assert_equal "racecar.jpg", user.reload.highlights.first.filename.to_s
+      assert_equal "video.mp4", user.highlights.second.filename.to_s
+    end
+  end
+
+  test "creating a record with existing blobs attached" do
+    user = User.create!(name: "Jason", highlights: [ create_blob(filename: "funky.jpg"), create_blob(filename: "town.jpg") ])
+    assert_equal "funky.jpg", user.reload.highlights.first.filename.to_s
+    assert_equal "town.jpg", user.reload.highlights.second.filename.to_s
+  end
+
+  test "creating a record with an existing blob from signed IDs attached" do
+    user = User.create!(name: "Jason", highlights: [
+      create_blob(filename: "funky.jpg").signed_id, create_blob(filename: "town.jpg").signed_id ])
+    assert_equal "funky.jpg", user.reload.highlights.first.filename.to_s
+    assert_equal "town.jpg", user.reload.highlights.second.filename.to_s
+  end
+
+  test "creating a record with new blobs from uploaded files attached" do
+    User.new(name: "Jason", highlights: [ fixture_file_upload("racecar.jpg"), fixture_file_upload("video.mp4") ]).tap do |user|
+      assert user.new_record?
+      assert user.highlights.first.new_record?
+      assert user.highlights.second.new_record?
+      assert user.highlights.first.blob.new_record?
+      assert user.highlights.second.blob.new_record?
+      assert_equal "racecar.jpg", user.highlights.first.filename.to_s
+      assert_equal "video.mp4", user.highlights.second.filename.to_s
+      assert_not ActiveStorage::Blob.service.exist?(user.highlights.first.key)
+      assert_not ActiveStorage::Blob.service.exist?(user.highlights.second.key)
+
+      user.save!
+      assert_equal "racecar.jpg", user.highlights.first.filename.to_s
+      assert_equal "video.mp4", user.highlights.second.filename.to_s
+    end
+  end
+
+  test "creating a record with an unexpected object attached" do
+    error = assert_raises { User.create!(name: "Jason", highlights: :foo) }
+    assert_equal "Could not find or build blob: expected attachable, got :foo", error.message
+  end
+
+  test "purging" do
+    [ create_blob(filename: "funky.jpg"), create_blob(filename: "town.jpg") ].tap do |blobs|
+      @user.highlights.attach blobs
+      assert @user.highlights.attached?
+
+      @user.highlights.purge
+      assert_not @user.highlights.attached?
+      assert_not ActiveStorage::Blob.exists?(blobs.first.id)
+      assert_not ActiveStorage::Blob.exists?(blobs.second.id)
+      assert_not ActiveStorage::Blob.service.exist?(blobs.first.key)
+      assert_not ActiveStorage::Blob.service.exist?(blobs.second.key)
+    end
+  end
+
+  test "purging later" do
+    [ create_blob(filename: "funky.jpg"), create_blob(filename: "town.jpg") ].tap do |blobs|
+      @user.highlights.attach blobs
+      assert @user.highlights.attached?
+
+      perform_enqueued_jobs do
+        @user.highlights.purge_later
+      end
+
+      assert_not @user.highlights.attached?
+      assert_not ActiveStorage::Blob.exists?(blobs.first.id)
+      assert_not ActiveStorage::Blob.exists?(blobs.second.id)
+      assert_not ActiveStorage::Blob.service.exist?(blobs.first.key)
+      assert_not ActiveStorage::Blob.service.exist?(blobs.second.key)
+    end
+  end
+
+  test "purging dependent attachment later on destroy" do
+    [ create_blob(filename: "funky.jpg"), create_blob(filename: "town.jpg") ].tap do |blobs|
+      @user.highlights.attach blobs
+
+      perform_enqueued_jobs do
+        @user.destroy!
+      end
+
+      assert_not ActiveStorage::Blob.exists?(blobs.first.id)
+      assert_not ActiveStorage::Blob.exists?(blobs.second.id)
+      assert_not ActiveStorage::Blob.service.exist?(blobs.first.key)
+      assert_not ActiveStorage::Blob.service.exist?(blobs.second.key)
+    end
+  end
+
+  test "not purging independent attachment on destroy" do
+    [ create_blob(filename: "funky.mp4"), create_blob(filename: "town.mp4") ].tap do |blobs|
+      @user.vlogs.attach blobs
+
+      assert_no_enqueued_jobs do
+        @user.destroy!
+      end
+    end
+  end
+
+  test "overriding attached reader" do
+    @user.highlights.attach create_blob(filename: "funky.jpg"), create_blob(filename: "town.jpg")
+
+    assert_equal "funky.jpg", @user.highlights.first.filename.to_s
+    assert_equal "town.jpg", @user.highlights.second.filename.to_s
+
+    begin
+      User.class_eval do
+        def highlights
+          super.reverse
+        end
+      end
+
+      assert_equal "town.jpg", @user.highlights.first.filename.to_s
+      assert_equal "funky.jpg", @user.highlights.second.filename.to_s
+    ensure
+      User.send(:remove_method, :highlights)
+    end
+  end
+end
diff --git a/activestorage/test/models/attached/one_test.rb b/activestorage/test/models/attached/one_test.rb
new file mode 100644
index 0000000000..af45b696ae
--- /dev/null
+++ b/activestorage/test/models/attached/one_test.rb
@@ -0,0 +1,329 @@
+# frozen_string_literal: true
+
+require "test_helper"
+require "database/setup"
+
+class ActiveStorage::OneAttachedTest < ActiveSupport::TestCase
+  include ActiveJob::TestHelper
+
+  setup do
+    @user = User.create!(name: "Josh")
+  end
+
+  teardown { ActiveStorage::Blob.all.each(&:purge) }
+
+  test "attaching an existing blob to an existing record" do
+    @user.avatar.attach create_blob(filename: "funky.jpg")
+    assert_equal "funky.jpg", @user.avatar.filename.to_s
+  end
+
+  test "attaching an existing blob from a signed ID to an existing record" do
+    @user.avatar.attach create_blob(filename: "funky.jpg").signed_id
+    assert_equal "funky.jpg", @user.avatar.filename.to_s
+  end
+
+  test "attaching a new blob from a Hash to an existing record" do
+    @user.avatar.attach io: StringIO.new("STUFF"), filename: "town.jpg", content_type: "image/jpg"
+    assert_equal "town.jpg", @user.avatar.filename.to_s
+  end
+
+  test "attaching a new blob from an uploaded file to an existing record" do
+    @user.avatar.attach fixture_file_upload("racecar.jpg")
+    assert_equal "racecar.jpg", @user.avatar.filename.to_s
+  end
+
+  test "updating an existing record to attach an existing blob" do
+    @user.update! avatar: create_blob(filename: "funky.jpg")
+    assert_equal "funky.jpg", @user.avatar.filename.to_s
+  end
+
+  test "updating an existing record to attach an existing blob from a signed ID" do
+    @user.update! avatar: create_blob(filename: "funky.jpg").signed_id
+    assert_equal "funky.jpg", @user.avatar.filename.to_s
+  end
+
+  test "successfully updating an existing record to attach a new blob from an uploaded file" do
+    @user.avatar = fixture_file_upload("racecar.jpg")
+    assert_equal "racecar.jpg", @user.avatar.filename.to_s
+    assert_not ActiveStorage::Blob.service.exist?(@user.avatar.key)
+
+    @user.save!
+    assert ActiveStorage::Blob.service.exist?(@user.avatar.key)
+  end
+
+  test "unsuccessfully updating an existing record to attach a new blob from an uploaded file" do
+    assert_not @user.update(name: "", avatar: fixture_file_upload("racecar.jpg"))
+    assert_equal "racecar.jpg", @user.avatar.filename.to_s
+    assert_not ActiveStorage::Blob.service.exist?(@user.avatar.key)
+  end
+
+  test "successfully replacing an existing, dependent attachment on an existing record" do
+    create_blob(filename: "funky.jpg").tap do |old_blob|
+      @user.avatar.attach old_blob
+
+      perform_enqueued_jobs do
+        @user.avatar.attach create_blob(filename: "town.jpg")
+      end
+
+      assert_equal "town.jpg", @user.avatar.filename.to_s
+      assert_not ActiveStorage::Blob.exists?(old_blob.id)
+      assert_not ActiveStorage::Blob.service.exist?(old_blob.key)
+    end
+  end
+
+  test "successfully replacing an existing, independent attachment on an existing record" do
+    @user.cover_photo.attach create_blob(filename: "funky.jpg")
+
+    assert_no_enqueued_jobs only: ActiveStorage::PurgeJob do
+      @user.cover_photo.attach create_blob(filename: "town.jpg")
+    end
+
+    assert_equal "town.jpg", @user.cover_photo.filename.to_s
+  end
+
+  test "unsuccessfully replacing an existing attachment on an existing record" do
+    @user.avatar.attach create_blob(filename: "funky.jpg")
+
+    assert_no_enqueued_jobs do
+      assert_raises do
+        @user.avatar.attach nil
+      end
+    end
+
+    assert_equal "funky.jpg", @user.avatar.filename.to_s
+    assert ActiveStorage::Blob.service.exist?(@user.avatar.key)
+  end
+
+  test "replacing an existing attachment on an existing record with the same blob" do
+    create_blob(filename: "funky.jpg").tap do |blob|
+      @user.avatar.attach blob
+
+      assert_no_changes -> { @user.reload.avatar_attachment.id } do
+        assert_no_enqueued_jobs do
+          @user.avatar.attach blob
+        end
+      end
+
+      assert_equal "funky.jpg", @user.avatar.filename.to_s
+      assert ActiveStorage::Blob.service.exist?(@user.avatar.key)
+    end
+  end
+
+  test "successfully updating an existing record to replace an existing, dependent attachment" do
+    create_blob(filename: "funky.jpg").tap do |old_blob|
+      @user.avatar.attach old_blob
+
+      perform_enqueued_jobs do
+        @user.update! avatar: create_blob(filename: "town.jpg")
+      end
+
+      assert_equal "town.jpg", @user.avatar.filename.to_s
+      assert_not ActiveStorage::Blob.exists?(old_blob.id)
+      assert_not ActiveStorage::Blob.service.exist?(old_blob.key)
+    end
+  end
+
+  test "successfully updating an existing record to replace an existing, independent attachment" do
+    @user.cover_photo.attach create_blob(filename: "funky.jpg")
+
+    assert_no_enqueued_jobs only: ActiveStorage::PurgeJob do
+      @user.update! cover_photo: create_blob(filename: "town.jpg")
+    end
+
+    assert_equal "town.jpg", @user.cover_photo.filename.to_s
+  end
+
+  test "unsuccessfully updating an existing record to replace an existing attachment" do
+    @user.avatar.attach create_blob(filename: "funky.jpg")
+
+    assert_no_enqueued_jobs do
+      assert_not @user.update(name: "", avatar: fixture_file_upload("racecar.jpg"))
+    end
+
+    assert_equal "racecar.jpg", @user.avatar.filename.to_s
+    assert_not ActiveStorage::Blob.service.exist?(@user.avatar.key)
+  end
+
+  test "updating an existing record to replace an attached blob with itself" do
+    create_blob(filename: "funky.jpg").tap do |blob|
+      @user.avatar.attach blob
+
+      assert_no_enqueued_jobs do
+        assert_no_changes -> { @user.avatar_attachment.id } do
+          @user.update! avatar: blob
+        end
+      end
+    end
+  end
+
+  test "successfully updating an existing record to remove a dependent attachment" do
+    create_blob(filename: "funky.jpg").tap do |blob|
+      @user.avatar.attach blob
+
+      perform_enqueued_jobs do
+        @user.update! avatar: nil
+      end
+
+      assert_not @user.avatar.attached?
+    end
+  end
+
+  test "successfully updating an existing record to remove an independent attachment" do
+    create_blob(filename: "funky.jpg").tap do |blob|
+      @user.cover_photo.attach blob
+
+      assert_no_enqueued_jobs only: ActiveStorage::PurgeJob do
+        @user.update! cover_photo: nil
+      end
+
+      assert_not @user.cover_photo.attached?
+      assert ActiveStorage::Blob.service.exist?(blob.key)
+    end
+  end
+
+  test "attaching an existing blob to a new record" do
+    User.new(name: "Jason").tap do |user|
+      user.avatar.attach create_blob(filename: "funky.jpg")
+      assert user.new_record?
+      assert_equal "funky.jpg", user.avatar.filename.to_s
+
+      user.save!
+      assert_equal "funky.jpg", user.reload.avatar.filename.to_s
+    end
+  end
+
+  test "attaching an existing blob from a signed ID to a new record" do
+    User.new(name: "Jason").tap do |user|
+      user.avatar.attach create_blob(filename: "funky.jpg").signed_id
+      assert user.new_record?
+      assert_equal "funky.jpg", user.avatar.filename.to_s
+
+      user.save!
+      assert_equal "funky.jpg", user.reload.avatar.filename.to_s
+    end
+  end
+
+  test "attaching a new blob from a Hash to a new record" do
+    User.new(name: "Jason").tap do |user|
+      user.avatar.attach io: StringIO.new("STUFF"), filename: "town.jpg", content_type: "image/jpg"
+      assert user.new_record?
+      assert user.avatar.attachment.new_record?
+      assert_not user.avatar.blob.new_record?
+      assert_equal "town.jpg", user.avatar.filename.to_s
+      assert ActiveStorage::Blob.service.exist?(user.avatar.key)
+
+      user.save!
+      assert_equal "town.jpg", user.reload.avatar.filename.to_s
+    end
+  end
+
+  test "attaching a new blob from an uploaded file to a new record" do
+    User.new(name: "Jason").tap do |user|
+      user.avatar.attach fixture_file_upload("racecar.jpg")
+      assert user.new_record?
+      assert user.avatar.attachment.new_record?
+      assert_not user.avatar.blob.new_record?
+      assert_equal "racecar.jpg", user.avatar.filename.to_s
+      assert ActiveStorage::Blob.service.exist?(user.avatar.key)
+
+      user.save!
+      assert_equal "racecar.jpg", user.reload.avatar.filename.to_s
+    end
+  end
+
+  test "creating a record with an existing blob attached" do
+    user = User.create!(name: "Jason", avatar: create_blob(filename: "funky.jpg"))
+    assert_equal "funky.jpg", user.reload.avatar.filename.to_s
+  end
+
+  test "creating a record with an existing blob from a signed ID attached" do
+    user = User.create!(name: "Jason", avatar: create_blob(filename: "funky.jpg").signed_id)
+    assert_equal "funky.jpg", user.reload.avatar.filename.to_s
+  end
+
+  test "creating a record with a new blob from an uploaded file attached" do
+    User.new(name: "Jason", avatar: fixture_file_upload("racecar.jpg")).tap do |user|
+      assert user.new_record?
+      assert user.avatar.attachment.new_record?
+      assert user.avatar.blob.new_record?
+      assert_equal "racecar.jpg", user.avatar.filename.to_s
+      assert_not ActiveStorage::Blob.service.exist?(user.avatar.key)
+
+      user.save!
+      assert_equal "racecar.jpg", user.reload.avatar.filename.to_s
+    end
+  end
+
+  test "creating a record with an unexpected object attached" do
+    error = assert_raises { User.create!(name: "Jason", avatar: :foo) }
+    assert_equal "Could not find or build blob: expected attachable, got :foo", error.message
+  end
+
+  test "purging" do
+    create_blob(filename: "funky.jpg").tap do |blob|
+      @user.avatar.attach blob
+      assert @user.avatar.attached?
+
+      @user.avatar.purge
+      assert_not @user.avatar.attached?
+      assert_not ActiveStorage::Blob.exists?(blob.id)
+      assert_not ActiveStorage::Blob.service.exist?(blob.key)
+    end
+  end
+
+  test "purging later" do
+    create_blob(filename: "funky.jpg").tap do |blob|
+      @user.avatar.attach blob
+      assert @user.avatar.attached?
+
+      perform_enqueued_jobs do
+        @user.avatar.purge_later
+      end
+
+      assert_not @user.avatar.attached?
+      assert_not ActiveStorage::Blob.exists?(blob.id)
+      assert_not ActiveStorage::Blob.service.exist?(blob.key)
+    end
+  end
+
+  test "purging dependent attachment later on destroy" do
+    create_blob(filename: "funky.jpg").tap do |blob|
+      @user.avatar.attach blob
+
+      perform_enqueued_jobs do
+        @user.destroy!
+      end
+
+      assert_not ActiveStorage::Blob.exists?(blob.id)
+      assert_not ActiveStorage::Blob.service.exist?(blob.key)
+    end
+  end
+
+  test "not purging independent attachment on destroy" do
+    create_blob(filename: "funky.jpg").tap do |blob|
+      @user.cover_photo.attach blob
+
+      assert_no_enqueued_jobs do
+        @user.destroy!
+      end
+    end
+  end
+
+  test "overriding attached reader" do
+    @user.avatar.attach create_blob(filename: "funky.jpg")
+
+    assert_equal "funky.jpg", @user.avatar.filename.to_s
+
+    begin
+      User.class_eval do
+        def avatar
+          super.filename.to_s.reverse
+        end
+      end
+
+      assert_equal "gpj.yknuf", @user.avatar
+    ensure
+      User.send(:remove_method, :avatar)
+    end
+  end
+end
diff --git a/activestorage/test/models/attached_test.rb b/activestorage/test/models/attached_test.rb
deleted file mode 100644
index b10d2bebe3..0000000000
--- a/activestorage/test/models/attached_test.rb
+++ /dev/null
@@ -1,56 +0,0 @@
-# frozen_string_literal: true
-
-require "test_helper"
-require "database/setup"
-
-class ActiveStorage::AttachmentsTest < ActiveSupport::TestCase
-  setup do
-    @user = User.create!(name: "Josh")
-  end
-
-  teardown { ActiveStorage::Blob.all.each(&:purge) }
-
-  test "overriding has_one_attached methods works" do
-    # attach blob before messing with getter, which breaks `#attach`
-    @user.avatar.attach create_blob(filename: "funky.jpg")
-
-    # inherited only
-    assert_equal "funky.jpg", @user.avatar.filename.to_s
-
-    begin
-      User.class_eval do
-        def avatar
-          super.filename.to_s.reverse
-        end
-      end
-
-      # override with super
-      assert_equal "funky.jpg".reverse, @user.avatar
-    ensure
-      User.send(:remove_method, :avatar)
-    end
-  end
-
-  test "overriding has_many_attached methods works" do
-    # attach blobs before messing with getter, which breaks `#attach`
-    @user.highlights.attach create_blob(filename: "funky.jpg"), create_blob(filename: "wonky.jpg")
-
-    # inherited only
-    assert_equal "funky.jpg", @user.highlights.first.filename.to_s
-    assert_equal "wonky.jpg", @user.highlights.second.filename.to_s
-
-    begin
-      User.class_eval do
-        def highlights
-          super.reverse
-        end
-      end
-
-      # override with super
-      assert_equal "wonky.jpg", @user.highlights.first.filename.to_s
-      assert_equal "funky.jpg", @user.highlights.second.filename.to_s
-    ensure
-      User.send(:remove_method, :highlights)
-    end
-  end
-end
diff --git a/activestorage/test/models/attachments_test.rb b/activestorage/test/models/attachments_test.rb
deleted file mode 100644
index ce83ec27d2..0000000000
--- a/activestorage/test/models/attachments_test.rb
+++ /dev/null
@@ -1,459 +0,0 @@
-# frozen_string_literal: true
-
-require "test_helper"
-require "database/setup"
-
-class ActiveStorage::AttachmentsTest < ActiveSupport::TestCase
-  include ActiveJob::TestHelper
-
-  setup { @user = User.create!(name: "DHH") }
-
-  teardown { ActiveStorage::Blob.all.each(&:purge) }
-
-  test "attach existing blob" do
-    @user.avatar.attach create_blob(filename: "funky.jpg")
-    assert_equal "funky.jpg", @user.avatar.filename.to_s
-  end
-
-  test "attach existing blob from a signed ID" do
-    @user.avatar.attach create_blob(filename: "funky.jpg").signed_id
-    assert_equal "funky.jpg", @user.avatar.filename.to_s
-  end
-
-  test "attach new blob from a Hash" do
-    @user.avatar.attach io: StringIO.new("STUFF"), filename: "town.jpg", content_type: "image/jpg"
-    assert_equal "town.jpg", @user.avatar.filename.to_s
-  end
-
-  test "attach new blob from an UploadedFile" do
-    file = file_fixture "racecar.jpg"
-    @user.avatar.attach Rack::Test::UploadedFile.new file.to_s
-    assert_equal "racecar.jpg", @user.avatar.filename.to_s
-  end
-
-  test "replace attached blob" do
-    @user.avatar.attach create_blob(filename: "funky.jpg")
-
-    perform_enqueued_jobs do
-      assert_no_difference -> { ActiveStorage::Blob.count } do
-        @user.avatar.attach create_blob(filename: "town.jpg")
-      end
-    end
-
-    assert_equal "town.jpg", @user.avatar.filename.to_s
-  end
-
-  test "replace attached blob unsuccessfully" do
-    @user.avatar.attach create_blob(filename: "funky.jpg")
-
-    perform_enqueued_jobs do
-      assert_raises do
-        @user.avatar.attach nil
-      end
-    end
-
-    assert_equal "funky.jpg", @user.reload.avatar.filename.to_s
-    assert ActiveStorage::Blob.service.exist?(@user.avatar.key)
-  end
-
-  test "replace attached blob with itself" do
-    @user.avatar.attach create_blob(filename: "funky.jpg")
-
-    assert_no_changes -> { @user.reload.avatar.blob } do
-      assert_no_changes -> { @user.reload.avatar.attachment } do
-        assert_no_enqueued_jobs do
-          @user.avatar.attach @user.avatar.blob
-        end
-      end
-    end
-  end
-
-  test "replaced attached blob with itself by signed ID" do
-    @user.avatar.attach create_blob(filename: "funky.jpg")
-
-    assert_no_changes -> { @user.reload.avatar.blob } do
-      assert_no_changes -> { @user.reload.avatar.attachment } do
-        assert_no_enqueued_jobs do
-          @user.avatar.attach @user.avatar.blob.signed_id
-        end
-      end
-    end
-  end
-
-  test "replace independent attached blob" do
-    @user.cover_photo.attach create_blob(filename: "funky.jpg")
-
-    perform_enqueued_jobs do
-      assert_difference -> { ActiveStorage::Blob.count }, +1 do
-        assert_no_difference -> { ActiveStorage::Attachment.count } do
-          @user.cover_photo.attach create_blob(filename: "town.jpg")
-        end
-      end
-    end
-
-    assert_equal "town.jpg", @user.cover_photo.filename.to_s
-  end
-
-  test "attach blob to new record" do
-    user = User.new(name: "Jason")
-
-    assert_no_changes -> { user.new_record? } do
-      assert_no_difference -> { ActiveStorage::Attachment.count } do
-        user.avatar.attach create_blob(filename: "funky.jpg")
-      end
-    end
-
-    assert_predicate user.avatar, :attached?
-    assert_equal "funky.jpg", user.avatar.filename.to_s
-
-    assert_difference -> { ActiveStorage::Attachment.count }, +1 do
-      user.save!
-    end
-
-    assert_predicate user.reload.avatar, :attached?
-    assert_equal "funky.jpg", user.avatar.filename.to_s
-  end
-
-  test "build new record with attached blob" do
-    assert_no_difference -> { ActiveStorage::Attachment.count } do
-      @user = User.new(name: "Jason", avatar: { io: StringIO.new("STUFF"), filename: "town.jpg", content_type: "image/jpg" })
-    end
-
-    assert_predicate @user, :new_record?
-    assert_predicate @user.avatar, :attached?
-    assert_equal "town.jpg", @user.avatar.filename.to_s
-
-    @user.save!
-    assert_predicate @user.reload.avatar, :attached?
-    assert_equal "town.jpg", @user.avatar.filename.to_s
-  end
-
-  test "access underlying associations of new blob" do
-    @user.avatar.attach create_blob(filename: "funky.jpg")
-    assert_equal @user, @user.avatar_attachment.record
-    assert_equal @user.avatar_attachment.blob, @user.avatar_blob
-    assert_equal "funky.jpg", @user.avatar_attachment.blob.filename.to_s
-  end
-
-  test "identify newly-attached, directly-uploaded blob" do
-    blob = directly_upload_file_blob(content_type: "application/octet-stream")
-
-    @user.avatar.attach(blob)
-
-    assert_equal "image/jpeg", @user.avatar.reload.content_type
-    assert_predicate @user.avatar, :identified?
-  end
-
-  test "identify and analyze newly-attached, directly-uploaded blob" do
-    blob = directly_upload_file_blob(content_type: "application/octet-stream")
-
-    perform_enqueued_jobs do
-      @user.avatar.attach blob
-    end
-
-    assert_equal true, @user.avatar.reload.metadata[:identified]
-    assert_equal 4104, @user.avatar.metadata[:width]
-    assert_equal 2736, @user.avatar.metadata[:height]
-  end
-
-  test "identify newly-attached blob only once" do
-    blob = create_file_blob
-    assert_predicate blob, :identified?
-
-    # The blob's backing file is a PNG image. Fudge its content type so we can tell if it's identified when we attach it.
-    blob.update! content_type: "application/octet-stream"
-
-    @user.avatar.attach blob
-    assert_equal "application/octet-stream", blob.content_type
-  end
-
-  test "analyze newly-attached blob" do
-    perform_enqueued_jobs do
-      @user.avatar.attach create_file_blob
-    end
-
-    assert_equal 4104, @user.avatar.reload.metadata[:width]
-    assert_equal 2736, @user.avatar.metadata[:height]
-  end
-
-  test "analyze attached blob only once" do
-    blob = create_file_blob
-
-    perform_enqueued_jobs do
-      @user.avatar.attach blob
-    end
-
-    assert_predicate blob.reload, :analyzed?
-
-    @user.avatar.detach
-
-    assert_no_enqueued_jobs do
-      @user.reload.avatar.attach blob
-    end
-  end
-
-  test "preserve existing metadata when analyzing a newly-attached blob" do
-    blob = create_file_blob(metadata: { foo: "bar" })
-
-    perform_enqueued_jobs do
-      @user.avatar.attach blob
-    end
-
-    assert_equal "bar", blob.reload.metadata[:foo]
-  end
-
-  test "detach blob" do
-    @user.avatar.attach create_blob(filename: "funky.jpg")
-    avatar_blob_id = @user.avatar.blob.id
-    avatar_key = @user.avatar.key
-
-    @user.avatar.detach
-    assert_not_predicate @user.avatar, :attached?
-    assert ActiveStorage::Blob.exists?(avatar_blob_id)
-    assert ActiveStorage::Blob.service.exist?(avatar_key)
-  end
-
-  test "purge attached blob" do
-    @user.avatar.attach create_blob(filename: "funky.jpg")
-    avatar_key = @user.avatar.key
-
-    @user.avatar.purge
-    assert_not_predicate @user.avatar, :attached?
-    assert_not ActiveStorage::Blob.service.exist?(avatar_key)
-  end
-
-  test "purge attached blob later when the record is destroyed" do
-    @user.avatar.attach create_blob(filename: "funky.jpg")
-    avatar_key = @user.avatar.key
-
-    perform_enqueued_jobs do
-      @user.reload.destroy
-
-      assert_nil ActiveStorage::Blob.find_by(key: avatar_key)
-      assert_not ActiveStorage::Blob.service.exist?(avatar_key)
-    end
-  end
-
-  test "delete attachment for independent blob when record is destroyed" do
-    @user.cover_photo.attach create_blob(filename: "funky.jpg")
-
-    @user.destroy
-    assert_not ActiveStorage::Attachment.exists?(record: @user, name: "cover_photo")
-  end
-
-  test "find with attached blob" do
-    records = %w[alice bob].map do |name|
-      User.create!(name: name).tap do |user|
-        user.avatar.attach create_blob(filename: "#{name}.jpg")
-      end
-    end
-
-    users = User.where(id: records.map(&:id)).with_attached_avatar.all
-
-    assert_equal "alice.jpg", users.first.avatar.filename.to_s
-    assert_equal "bob.jpg", users.second.avatar.filename.to_s
-  end
-
-
-  test "attach existing blobs" do
-    @user.highlights.attach create_blob(filename: "funky.jpg"), create_blob(filename: "wonky.jpg")
-
-    assert_equal "funky.jpg", @user.highlights.first.filename.to_s
-    assert_equal "wonky.jpg", @user.highlights.second.filename.to_s
-  end
-
-  test "attach new blobs" do
-    @user.highlights.attach(
-      { io: StringIO.new("STUFF"), filename: "town.jpg", content_type: "image/jpg" },
-      { io: StringIO.new("IT"), filename: "country.jpg", content_type: "image/jpg" })
-
-    assert_equal "town.jpg", @user.highlights.first.filename.to_s
-    assert_equal "country.jpg", @user.highlights.second.filename.to_s
-  end
-
-  test "attach blobs to new record" do
-    user = User.new(name: "Jason")
-
-    assert_no_changes -> { user.new_record? } do
-      assert_no_difference -> { ActiveStorage::Attachment.count } do
-        user.highlights.attach(
-          { io: StringIO.new("STUFF"), filename: "town.jpg", content_type: "image/jpg" },
-          { io: StringIO.new("IT"), filename: "country.jpg", content_type: "image/jpg" })
-      end
-    end
-
-    assert_predicate user.highlights, :attached?
-    assert_equal "town.jpg", user.highlights.first.filename.to_s
-    assert_equal "country.jpg", user.highlights.second.filename.to_s
-
-    assert_difference -> { ActiveStorage::Attachment.count }, +2 do
-      user.save!
-    end
-
-    assert_predicate user.reload.highlights, :attached?
-    assert_equal "town.jpg", user.highlights.first.filename.to_s
-    assert_equal "country.jpg", user.highlights.second.filename.to_s
-  end
-
-  test "build new record with attached blobs" do
-    assert_no_difference -> { ActiveStorage::Attachment.count } do
-      @user = User.new(name: "Jason", highlights: [
-        { io: StringIO.new("STUFF"), filename: "town.jpg", content_type: "image/jpg" },
-        { io: StringIO.new("IT"), filename: "country.jpg", content_type: "image/jpg" }])
-    end
-
-    assert_predicate @user, :new_record?
-    assert_predicate @user.highlights, :attached?
-    assert_equal "town.jpg", @user.highlights.first.filename.to_s
-    assert_equal "country.jpg", @user.highlights.second.filename.to_s
-
-    @user.save!
-    assert_predicate @user.reload.highlights, :attached?
-    assert_equal "town.jpg", @user.highlights.first.filename.to_s
-    assert_equal "country.jpg", @user.highlights.second.filename.to_s
-  end
-
-  test "find attached blobs" do
-    @user.highlights.attach(
-      { io: StringIO.new("STUFF"), filename: "town.jpg", content_type: "image/jpg" },
-      { io: StringIO.new("IT"), filename: "country.jpg", content_type: "image/jpg" })
-
-    highlights = User.where(id: @user.id).with_attached_highlights.first.highlights
-
-    assert_equal "town.jpg", highlights.first.filename.to_s
-    assert_equal "country.jpg", highlights.second.filename.to_s
-  end
-
-  test "access underlying associations of new blobs" do
-    @user.highlights.attach(
-      { io: StringIO.new("STUFF"), filename: "town.jpg", content_type: "image/jpg" },
-      { io: StringIO.new("IT"), filename: "country.jpg", content_type: "image/jpg" })
-
-    assert_equal @user, @user.highlights_attachments.first.record
-    assert_equal @user.highlights_attachments.collect(&:blob).sort, @user.highlights_blobs.sort
-    assert_equal "town.jpg", @user.highlights_attachments.first.blob.filename.to_s
-  end
-
-  test "analyze newly-attached blobs" do
-    perform_enqueued_jobs do
-      @user.highlights.attach(
-        create_file_blob(filename: "racecar.jpg", content_type: "image/jpeg"),
-        create_file_blob(filename: "video.mp4", content_type: "video/mp4"))
-    end
-
-    assert_equal 4104, @user.highlights.first.metadata[:width]
-    assert_equal 2736, @user.highlights.first.metadata[:height]
-
-    assert_equal 640, @user.highlights.second.metadata[:width]
-    assert_equal 480, @user.highlights.second.metadata[:height]
-  end
-
-  test "analyze attached blobs only once" do
-    blobs = [
-      create_file_blob(filename: "racecar.jpg", content_type: "image/jpeg"),
-      create_file_blob(filename: "video.mp4", content_type: "video/mp4")
-    ]
-
-    perform_enqueued_jobs do
-      @user.highlights.attach(blobs)
-    end
-
-    assert blobs.each(&:reload).all?(&:analyzed?)
-
-    @user.highlights.attachments.destroy_all
-
-    assert_no_enqueued_jobs do
-      @user.highlights.attach(blobs)
-    end
-  end
-
-  test "preserve existing metadata when analyzing newly-attached blobs" do
-    blobs = [
-      create_file_blob(filename: "racecar.jpg", content_type: "image/jpeg", metadata: { foo: "bar" }),
-      create_file_blob(filename: "video.mp4", content_type: "video/mp4", metadata: { foo: "bar" })
-    ]
-
-    perform_enqueued_jobs do
-      @user.highlights.attach(blobs)
-    end
-
-    blobs.each do |blob|
-      assert_equal "bar", blob.reload.metadata[:foo]
-    end
-  end
-
-  test "detach blobs" do
-    @user.highlights.attach create_blob(filename: "funky.jpg"), create_blob(filename: "wonky.jpg")
-    highlight_blob_ids = @user.highlights.collect { |highlight| highlight.blob.id }
-    highlight_keys = @user.highlights.collect(&:key)
-
-    @user.highlights.detach
-    assert_not_predicate @user.highlights, :attached?
-
-    assert ActiveStorage::Blob.exists?(highlight_blob_ids.first)
-    assert ActiveStorage::Blob.exists?(highlight_blob_ids.second)
-
-    assert ActiveStorage::Blob.service.exist?(highlight_keys.first)
-    assert ActiveStorage::Blob.service.exist?(highlight_keys.second)
-  end
-
-  test "purge attached blobs" do
-    @user.highlights.attach create_blob(filename: "funky.jpg"), create_blob(filename: "wonky.jpg")
-    highlight_keys = @user.highlights.collect(&:key)
-
-    @user.highlights.purge
-    assert_not_predicate @user.highlights, :attached?
-    assert_not ActiveStorage::Blob.service.exist?(highlight_keys.first)
-    assert_not ActiveStorage::Blob.service.exist?(highlight_keys.second)
-  end
-
-  test "purge attached blobs later when the record is destroyed" do
-    @user.highlights.attach create_blob(filename: "funky.jpg"), create_blob(filename: "wonky.jpg")
-    highlight_keys = @user.highlights.collect(&:key)
-
-    perform_enqueued_jobs do
-      @user.reload.destroy
-
-      assert_nil ActiveStorage::Blob.find_by(key: highlight_keys.first)
-      assert_not ActiveStorage::Blob.service.exist?(highlight_keys.first)
-
-      assert_nil ActiveStorage::Blob.find_by(key: highlight_keys.second)
-      assert_not ActiveStorage::Blob.service.exist?(highlight_keys.second)
-    end
-  end
-
-  test "delete attachments for independent blobs when the record is destroyed" do
-    @user.vlogs.attach create_blob(filename: "funky.mp4"), create_blob(filename: "wonky.mp4")
-
-    @user.destroy
-    assert_not ActiveStorage::Attachment.exists?(record: @user, name: "vlogs")
-  end
-
-  test "selectively purge one attached blob of many" do
-    first_blob  = create_blob(filename: "funky.jpg")
-    second_blob = create_blob(filename: "wonky.jpg")
-    attachments = @user.highlights.attach(first_blob, second_blob)
-
-    assert_difference -> { ActiveStorage::Blob.count }, -1 do
-      @user.highlights.where(id: attachments.first.id).purge
-    end
-
-    assert_not ActiveStorage::Blob.exists?(key: first_blob.key)
-    assert ActiveStorage::Blob.exists?(key: second_blob.key)
-  end
-
-  test "selectively purge one attached blob of many later" do
-    first_blob  = create_blob(filename: "funky.jpg")
-    second_blob = create_blob(filename: "wonky.jpg")
-    attachments = @user.highlights.attach(first_blob, second_blob)
-
-    perform_enqueued_jobs do
-      assert_difference -> { ActiveStorage::Blob.count }, -1 do
-        @user.highlights.where(id: attachments.first.id).purge_later
-      end
-    end
-
-    assert_not ActiveStorage::Blob.exists?(key: first_blob.key)
-    assert ActiveStorage::Blob.exists?(key: second_blob.key)
-  end
-end
diff --git a/activestorage/test/models/blob_test.rb b/activestorage/test/models/blob_test.rb
index 40b30acd3e..a0e207642a 100644
--- a/activestorage/test/models/blob_test.rb
+++ b/activestorage/test/models/blob_test.rb
@@ -7,21 +7,15 @@ require "active_support/testing/method_call_assertions"
 class ActiveStorage::BlobTest < ActiveSupport::TestCase
   include ActiveSupport::Testing::MethodCallAssertions
 
-  test ".unattached scope returns not attached blobs" do
-    class UserWithHasOneAttachedDependentFalse < User
-      has_one_attached :avatar, dependent: false
+  test "unattached scope" do
+    [ create_blob(filename: "funky.jpg"), create_blob(filename: "town.jpg") ].tap do |blobs|
+      User.create! name: "DHH", avatar: blobs.first
+      assert_includes ActiveStorage::Blob.unattached, blobs.second
+      assert_not_includes ActiveStorage::Blob.unattached, blobs.first
+
+      User.create! name: "Jason", avatar: blobs.second
+      assert_not_includes ActiveStorage::Blob.unattached, blobs.second
     end
-
-    ActiveStorage::Blob.delete_all
-    blob_1 = create_blob filename: "funky.jpg"
-    blob_2 = create_blob filename: "town.jpg"
-
-    user = UserWithHasOneAttachedDependentFalse.create!
-    user.avatar.attach blob_1
-
-    assert_equal [blob_2], ActiveStorage::Blob.unattached
-    user.destroy
-    assert_equal [blob_1, blob_2].map(&:id).sort, ActiveStorage::Blob.unattached.pluck(:id).sort
   end
 
   test "create after upload sets byte size and checksum" do
diff --git a/activestorage/test/models/presence_validation_test.rb b/activestorage/test/models/presence_validation_test.rb
index aa804506dd..13ba3c900d 100644
--- a/activestorage/test/models/presence_validation_test.rb
+++ b/activestorage/test/models/presence_validation_test.rb
@@ -12,7 +12,7 @@ class ActiveStorage::PresenceValidationTest < ActiveSupport::TestCase
 
   test "validates_presence_of has_one_attached" do
     Admin.validates_presence_of :avatar
-    a = Admin.new
+    a = Admin.new(name: "DHH")
     assert_predicate a, :invalid?
 
     a.avatar.attach create_blob(filename: "funky.jpg")
@@ -21,7 +21,7 @@ class ActiveStorage::PresenceValidationTest < ActiveSupport::TestCase
 
   test "validates_presence_of has_many_attached" do
     Admin.validates_presence_of :highlights
-    a = Admin.new
+    a = Admin.new(name: "DHH")
     assert_predicate a, :invalid?
 
     a.highlights.attach create_blob(filename: "funky.jpg")
diff --git a/activestorage/test/test_helper.rb b/activestorage/test/test_helper.rb
index 9985a76832..7b7926ac79 100644
--- a/activestorage/test/test_helper.rb
+++ b/activestorage/test/test_helper.rb
@@ -79,6 +79,10 @@ class ActiveSupport::TestCase
     def extract_metadata_from(blob)
       blob.tap(&:analyze).metadata
     end
+
+    def fixture_file_upload(filename)
+      Rack::Test::UploadedFile.new file_fixture(filename).to_s
+    end
 end
 
 require "global_id"
@@ -86,6 +90,8 @@ GlobalID.app = "ActiveStorageExampleApp"
 ActiveRecord::Base.send :include, GlobalID::Identification
 
 class User < ActiveRecord::Base
+  validates :name, presence: true
+
   has_one_attached :avatar
   has_one_attached :cover_photo, dependent: false