chore: Minor changes to dummy app migrations

spec/dummy/db/migrate/20170806125915_create_active_storage_tables.active_storage.rb

@@ -1,27 +0,0 @@
-# This migration comes from active_storage (originally 20170806125915)
-class CreateActiveStorageTables < ActiveRecord::Migration[5.2]
-  def change
-    create_table :active_storage_blobs do |t|
-      t.string   :key,        null: false
-      t.string   :filename,   null: false
-      t.string   :content_type
-      t.text     :metadata
-      t.bigint   :byte_size,  null: false
-      t.string   :checksum,   null: false
-      t.datetime :created_at, null: false
-
-      t.index [ :key ], unique: true
-    end
-
-    create_table :active_storage_attachments do |t|
-      t.string     :name,     null: false
-      t.references :record,   null: false, polymorphic: true, index: false
-      t.references :blob,     null: false
-
-      t.datetime :created_at, null: false
-
-      t.index [ :record_type, :record_id, :name, :blob_id ], name: "index_active_storage_attachments_uniqueness", unique: true
-      t.foreign_key :active_storage_blobs, column: :blob_id
-    end
-  end
-end

spec/dummy/db/migrate/20180101010101_create_active_admin_comments.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class CreateActiveAdminComments < ActiveRecord::Migration[6.0]
   def self.up
     create_table :active_admin_comments do |t|

spec/dummy/db/migrate/20180101010102_create_active_storage_tables.active_storage.rb

@@ -0,0 +1,59 @@
+# frozen_string_literal: true
+# This migration comes from active_storage (originally 20170806125915)
+
+class CreateActiveStorageTables < ActiveRecord::Migration[6.0]
+  def change
+    # Use Active Record's configured type for primary and foreign keys
+    primary_key_type, foreign_key_type = primary_and_foreign_key_types
+
+    create_table :active_storage_blobs, id: primary_key_type do |t|
+      t.string   :key,          null: false
+      t.string   :filename,     null: false
+      t.string   :content_type
+      t.text     :metadata
+      t.string   :service_name, null: false
+      t.bigint   :byte_size,    null: false
+      t.string   :checksum
+
+      if connection.supports_datetime_with_precision?
+        t.datetime :created_at, precision: 6, null: false
+      else
+        t.datetime :created_at, null: false
+      end
+
+      t.index [ :key ], unique: true
+    end
+
+    create_table :active_storage_attachments, id: primary_key_type do |t|
+      t.string     :name,     null: false
+      t.references :record,   null: false, polymorphic: true, index: false, type: foreign_key_type
+      t.references :blob,     null: false, type: foreign_key_type
+
+      if connection.supports_datetime_with_precision?
+        t.datetime :created_at, precision: 6, null: false
+      else
+        t.datetime :created_at, null: false
+      end
+
+      t.index [ :record_type, :record_id, :name, :blob_id ], name: :index_active_storage_attachments_uniqueness, unique: true
+      t.foreign_key :active_storage_blobs, column: :blob_id
+    end
+
+    create_table :active_storage_variant_records, id: primary_key_type do |t|
+      t.belongs_to :blob, null: false, index: false, type: foreign_key_type
+      t.string :variation_digest, null: false
+
+      t.index [ :blob_id, :variation_digest ], name: :index_active_storage_variant_records_uniqueness, unique: true
+      t.foreign_key :active_storage_blobs, column: :blob_id
+    end
+  end
+
+  private
+    def primary_and_foreign_key_types
+      config = Rails.configuration.generators
+      setting = config.options[config.orm][:primary_key_type]
+      primary_key_type = setting || :primary_key
+      foreign_key_type = setting || :bigint
+      [ primary_key_type, foreign_key_type ]
+    end
+end

spec/dummy/db/migrate/20180607053251_create_authors.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-class CreateAuthors < ActiveRecord::Migration[5.2]
+class CreateAuthors < ActiveRecord::Migration[6.0]
   def change
     create_table :authors do |t|
       t.string :name

spec/dummy/db/migrate/20180607053254_create_profiles.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-class CreateProfiles < ActiveRecord::Migration[5.2]
+class CreateProfiles < ActiveRecord::Migration[6.0]
   def change
     create_table :profiles do |t|
       t.text :description

spec/dummy/db/migrate/20180607053255_create_tags.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-class CreateTags < ActiveRecord::Migration[5.2]
+class CreateTags < ActiveRecord::Migration[6.0]
   def change
     create_table :tags do |t|
       t.string :name

spec/dummy/db/migrate/20180607053257_create_post_tags.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-class CreatePostTags < ActiveRecord::Migration[5.2]
+class CreatePostTags < ActiveRecord::Migration[6.0]
   def change
     create_table :post_tags do |t|
       t.belongs_to :post, foreign_key: true

spec/dummy/db/migrate/20180607053739_create_posts.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-class CreatePosts < ActiveRecord::Migration[5.2]
+class CreatePosts < ActiveRecord::Migration[6.0]
   def change
     create_table :posts do |t|
       t.string :title