From 1966c188cfb06b39a47082e2f6c6e33a43668ae5 Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@loudthinking.com>
Date: Tue, 11 Jul 2017 18:53:17 +0200
Subject: Very incomplete first stab

---
 Gemfile                                            |   1 +
 Gemfile.lock                                       |   2 +
 .../controllers/variants_controller.rb             |  22 ++++++++
 lib/active_storage/engine.rb                       |  59 +++++++++++++--------
 lib/active_storage/routes.rb                       |   1 +
 lib/active_storage/variant.rb                      |  52 ++++++++++++++++++
 lib/active_storage/verified_key_with_expiration.rb |   2 +-
 test/fixtures/files/racecar.jpg                    | Bin 0 -> 1124062 bytes
 test/test_helper.rb                                |   3 ++
 test/variation_test.rb                             |  16 ++++++
 10 files changed, 134 insertions(+), 24 deletions(-)
 create mode 100644 lib/active_storage/controllers/variants_controller.rb
 create mode 100644 lib/active_storage/variant.rb
 create mode 100644 test/fixtures/files/racecar.jpg
 create mode 100644 test/variation_test.rb

diff --git a/Gemfile b/Gemfile
index a757a5c793..c4ecf50bbe 100644
--- a/Gemfile
+++ b/Gemfile
@@ -10,3 +10,4 @@ gem 'httparty'
 
 gem 'aws-sdk', '~> 2', require: false
 gem 'google-cloud-storage', require: false
+gem 'mini_magick'
diff --git a/Gemfile.lock b/Gemfile.lock
index 7e4c6f78f2..8d0c4c7937 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -99,6 +99,7 @@ GEM
     mime-types (3.1)
       mime-types-data (~> 3.2015)
     mime-types-data (3.2016.0521)
+    mini_magick (4.8.0)
     mini_portile2 (2.1.0)
     minitest (5.10.2)
     multi_json (1.12.1)
@@ -143,6 +144,7 @@ DEPENDENCIES
   byebug
   google-cloud-storage
   httparty
+  mini_magick
   rake
   sqlite3
 
diff --git a/lib/active_storage/controllers/variants_controller.rb b/lib/active_storage/controllers/variants_controller.rb
new file mode 100644
index 0000000000..24cee16e80
--- /dev/null
+++ b/lib/active_storage/controllers/variants_controller.rb
@@ -0,0 +1,22 @@
+require "action_controller"
+require "active_storage/blob"
+
+class ActiveStorage::Controllers::VariantsController < ActionController::Base
+  def show
+    if blob_key = decode_verified_key
+      variant = ActiveStorage::Variant.lookup(blob_key: blob_key, variation_key: params[:variation_key])
+      redirect_to variant.url
+    else
+      head :not_found
+    end
+  end
+
+  private
+    def decode_verified_key
+      ActiveStorage::VerifiedKeyWithExpiration.decode(params[:encoded_key])
+    end
+
+    def disposition_param
+      params[:disposition].presence_in(%w( inline attachment )) || 'inline'
+    end
+end
diff --git a/lib/active_storage/engine.rb b/lib/active_storage/engine.rb
index c251f522c6..8918b179e0 100644
--- a/lib/active_storage/engine.rb
+++ b/lib/active_storage/engine.rb
@@ -33,29 +33,42 @@ module ActiveStorage
       end
     end
 
-    config.after_initialize do |app|
-      if config_choice = app.config.active_storage.service
-        config_file = Pathname.new(Rails.root.join("config/storage_services.yml"))
-        raise("Couldn't find Active Storage configuration in #{config_file}") unless config_file.exist?
-
-        require "yaml"
-        require "erb"
-
-        configs =
-          begin
-            YAML.load(ERB.new(config_file.read).result) || {}
-          rescue Psych::SyntaxError => e
-            raise "YAML syntax error occurred while parsing #{config_file}. " \
-                  "Please note that YAML must be consistently indented using spaces. Tabs are not allowed. " \
-                  "Error: #{e.message}"
-          end
-
-        ActiveStorage::Blob.service =
-          begin
-            ActiveStorage::Service.configure config_choice, configs
-          rescue => e
-            raise e, "Cannot load `Rails.config.active_storage.service`:\n#{e.message}", e.backtrace
-          end
+    initializer "active_storage.verifiers" do
+      require "active_storage/verified_key_with_expiration"
+      require "active_storage/variant"
+
+      config.after_initialize do |app|
+        ActiveStorage::VerifiedKeyWithExpiration.verifier = \
+        ActiveStorage::Variant.verifier = \
+          Rails.application.message_verifier('ActiveStorage')
+      end
+    end
+
+    initializer "active_storage.services" do
+      config.after_initialize do |app|
+        if config_choice = app.config.active_storage.service
+          config_file = Pathname.new(Rails.root.join("config/storage_services.yml"))
+          raise("Couldn't find Active Storage configuration in #{config_file}") unless config_file.exist?
+
+          require "yaml"
+          require "erb"
+
+          configs =
+            begin
+              YAML.load(ERB.new(config_file.read).result) || {}
+            rescue Psych::SyntaxError => e
+              raise "YAML syntax error occurred while parsing #{config_file}. " \
+                    "Please note that YAML must be consistently indented using spaces. Tabs are not allowed. " \
+                    "Error: #{e.message}"
+            end
+
+          ActiveStorage::Blob.service =
+            begin
+              ActiveStorage::Service.configure config_choice, configs
+            rescue => e
+              raise e, "Cannot load `Rails.config.active_storage.service`:\n#{e.message}", e.backtrace
+            end
+        end
       end
     end
   end
diff --git a/lib/active_storage/routes.rb b/lib/active_storage/routes.rb
index 748427a776..fade234ad3 100644
--- a/lib/active_storage/routes.rb
+++ b/lib/active_storage/routes.rb
@@ -1,2 +1,3 @@
 get  "/rails/active_storage/disk/:encoded_key/*filename" => "active_storage/disk#show", as: :rails_disk_blob
+get  "/rails/active_storage/variants/:encoded_key/:encoded_transformation/*filename" => "active_storage/controllers/variants#show", as: :rails_blob_variant
 post "/rails/active_storage/direct_uploads" => "active_storage/direct_uploads#create", as: :rails_direct_uploads
diff --git a/lib/active_storage/variant.rb b/lib/active_storage/variant.rb
new file mode 100644
index 0000000000..9b9dad43da
--- /dev/null
+++ b/lib/active_storage/variant.rb
@@ -0,0 +1,52 @@
+require "active_storage/blob"
+require "mini_magick"
+
+class ActiveStorage::Variant
+  class_attribute :verifier
+
+  attr_reader :blob, :variation
+  delegate :service, to: :blob
+
+  def self.lookup(blob_key:, variation_key:)
+    new ActiveStorage::Blob.find_by!(key: blob_key), variation: verifier.verify(variation_key)
+  end
+
+  def self.encode_key(variation)
+    verifier.generate(variation)
+  end
+
+  def initialize(blob, variation:)
+    @blob, @variation = blob, variation
+  end
+
+  def url(expires_in: 5.minutes, disposition: :inline)
+    perform unless exist?
+    service.url key, expires_in: expires_in, disposition: disposition, filename: blob.filename
+  end
+
+  def key
+    verifier.generate(variation)
+  end
+
+  private
+    def perform
+      upload_variant transform(download_blob)
+    end
+
+    def download_blob
+      service.download(blob.key)
+    end
+
+    def upload_variant(variation)
+      service.upload key, variation
+    end
+
+    def transform(io)
+      # FIXME: Actually do a variant based on the variation
+      File.open MiniMagick::Image.read(io).resize("500x500").path
+    end
+
+    def exist?
+      service.exist?(key)
+    end
+end
diff --git a/lib/active_storage/verified_key_with_expiration.rb b/lib/active_storage/verified_key_with_expiration.rb
index 8708106735..4a46483db5 100644
--- a/lib/active_storage/verified_key_with_expiration.rb
+++ b/lib/active_storage/verified_key_with_expiration.rb
@@ -1,5 +1,5 @@
 class ActiveStorage::VerifiedKeyWithExpiration
-  class_attribute :verifier, default: defined?(Rails) ? Rails.application.message_verifier('ActiveStorage') : nil
+  class_attribute :verifier
 
   class << self
     def encode(key, expires_in: nil)
diff --git a/test/fixtures/files/racecar.jpg b/test/fixtures/files/racecar.jpg
new file mode 100644
index 0000000000..934b4caa22
Binary files /dev/null and b/test/fixtures/files/racecar.jpg differ
diff --git a/test/test_helper.rb b/test/test_helper.rb
index 03593b12c7..878ce8391c 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -24,6 +24,9 @@ ActiveStorage::Service.logger = ActiveSupport::Logger.new(STDOUT)
 require "active_storage/verified_key_with_expiration"
 ActiveStorage::VerifiedKeyWithExpiration.verifier = ActiveSupport::MessageVerifier.new("Testing")
 
+require "active_storage/variant"
+ActiveStorage::Variant.verifier = ActiveSupport::MessageVerifier.new("Testing")
+
 class ActiveSupport::TestCase
   private
     def create_blob(data: "Hello world!", filename: "hello.txt", content_type: "text/plain")
diff --git a/test/variation_test.rb b/test/variation_test.rb
new file mode 100644
index 0000000000..3b05095292
--- /dev/null
+++ b/test/variation_test.rb
@@ -0,0 +1,16 @@
+require "test_helper"
+require "database/setup"
+require "active_storage/variant"
+
+class ActiveStorage::VariationTest < ActiveSupport::TestCase
+  test "square variation" do
+    blob = ActiveStorage::Blob.create_after_upload! \
+      io: File.open(File.expand_path("../fixtures/files/racecar.jpg", __FILE__)), filename: "racecar.jpg", content_type: "image/jpeg"
+
+    variation_key = ActiveStorage::Variant.encode_key(resize: "500x500")
+
+    variant = ActiveStorage::Variant.lookup(blob_key: blob.key, variation_key: variation_key)
+
+    assert_match /racecar.jpg/, variant.url
+  end
+end
-- 
cgit v1.2.3


From 710957b20a24d0c62219cb7cc229c52905d74b3d Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@loudthinking.com>
Date: Thu, 20 Jul 2017 14:04:54 -0500
Subject: Double confetti

---
 Gemfile | 2 --
 1 file changed, 2 deletions(-)

diff --git a/Gemfile b/Gemfile
index adc1e320e2..953b85ccfe 100644
--- a/Gemfile
+++ b/Gemfile
@@ -18,8 +18,6 @@ gem "httparty"
 gem "aws-sdk", "~> 2", require: false
 gem "google-cloud-storage", "~> 1.3", require: false
 
-gem 'aws-sdk', '~> 2', require: false
-gem 'google-cloud-storage', require: false
 gem 'mini_magick'
 
 gem "rubocop", require: false
-- 
cgit v1.2.3


From 66d94ed78dced24cdd186e8bb5877cc6d43f5da8 Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@loudthinking.com>
Date: Thu, 20 Jul 2017 14:05:03 -0500
Subject: Easier access to the variant of a blob

---
 lib/active_storage/blob.rb | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/lib/active_storage/blob.rb b/lib/active_storage/blob.rb
index 1a15361747..a9d9b8771c 100644
--- a/lib/active_storage/blob.rb
+++ b/lib/active_storage/blob.rb
@@ -1,6 +1,7 @@
 require "active_storage/service"
 require "active_storage/filename"
 require "active_storage/purge_job"
+require "active_storage/variant"
 
 # Schema: id, key, filename, content_type, metadata, byte_size, checksum, created_at
 class ActiveStorage::Blob < ActiveRecord::Base
@@ -40,6 +41,10 @@ class ActiveStorage::Blob < ActiveRecord::Base
     ActiveStorage::Filename.new(self[:filename])
   end
 
+  def variant(variation)
+    ActiveStorage::Variant.new(self, variation: variation)
+  end
+
   def url(expires_in: 5.minutes, disposition: :inline)
     service.url key, expires_in: expires_in, disposition: disposition, filename: filename
   end
-- 
cgit v1.2.3


From 5dbe5eaeb84b470624f1a2785315ddd4f7b1a4e3 Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@loudthinking.com>
Date: Thu, 20 Jul 2017 14:05:18 -0500
Subject: Follow AR like naming of factory method

---
 lib/active_storage/controllers/variants_controller.rb | 2 +-
 lib/active_storage/variant.rb                         | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/active_storage/controllers/variants_controller.rb b/lib/active_storage/controllers/variants_controller.rb
index 24cee16e80..094f94e706 100644
--- a/lib/active_storage/controllers/variants_controller.rb
+++ b/lib/active_storage/controllers/variants_controller.rb
@@ -4,7 +4,7 @@ require "active_storage/blob"
 class ActiveStorage::Controllers::VariantsController < ActionController::Base
   def show
     if blob_key = decode_verified_key
-      variant = ActiveStorage::Variant.lookup(blob_key: blob_key, variation_key: params[:variation_key])
+      variant = ActiveStorage::Variant.find_or_create_by(blob_key: blob_key, variation_key: params[:variation_key])
       redirect_to variant.url
     else
       head :not_found
diff --git a/lib/active_storage/variant.rb b/lib/active_storage/variant.rb
index 9b9dad43da..f005454b00 100644
--- a/lib/active_storage/variant.rb
+++ b/lib/active_storage/variant.rb
@@ -7,7 +7,7 @@ class ActiveStorage::Variant
   attr_reader :blob, :variation
   delegate :service, to: :blob
 
-  def self.lookup(blob_key:, variation_key:)
+  def self.find_or_create_by(blob_key:, variation_key:)
     new ActiveStorage::Blob.find_by!(key: blob_key), variation: verifier.verify(variation_key)
   end
 
-- 
cgit v1.2.3


From 76395e3c1b997da7b3853b1b3e94b712b1a29ecf Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@loudthinking.com>
Date: Thu, 20 Jul 2017 14:05:40 -0500
Subject: Do real transformations in a safe way

---
 lib/active_storage/variant.rb | 24 ++++++++++++++++++++----
 1 file changed, 20 insertions(+), 4 deletions(-)

diff --git a/lib/active_storage/variant.rb b/lib/active_storage/variant.rb
index f005454b00..62262c7790 100644
--- a/lib/active_storage/variant.rb
+++ b/lib/active_storage/variant.rb
@@ -1,9 +1,15 @@
 require "active_storage/blob"
+require "active_support/core_ext/object/inclusion"
 require "mini_magick"
 
 class ActiveStorage::Variant
   class_attribute :verifier
 
+  ALLOWED_TRANSFORMATIONS = %i(
+    resize rotate format flip fill monochrome orient quality roll scale sharpen shave shear size thumbnail
+    transparent transpose transverse trim background bordercolor compress crop
+  )
+
   attr_reader :blob, :variation
   delegate :service, to: :blob
 
@@ -42,11 +48,21 @@ class ActiveStorage::Variant
     end
 
     def transform(io)
-      # FIXME: Actually do a variant based on the variation
-      File.open MiniMagick::Image.read(io).resize("500x500").path
+      File.open \
+        MiniMagick::Image.read(io).tap { |transforming_image|
+          variation.each do |(method, argument)|
+            if method = allowed_transformational_method(method.to_sym)
+              if argument.present?
+                transforming_image.public_send(method, argument)
+              else
+                transforming_image.public_send(method)
+              end
+            end
+          end
+        }.path
     end
 
-    def exist?
-      service.exist?(key)
+    def allowed_transformational_method(method)
+      method.presence_in(ALLOWED_TRANSFORMATIONS)
     end
 end
-- 
cgit v1.2.3


From f1523ab39e38bdc031c3bfb61ed4b6decd23ffcd Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@loudthinking.com>
Date: Thu, 20 Jul 2017 14:06:00 -0500
Subject: Use a unique blob variant key for storage

---
 lib/active_storage/variant.rb | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/lib/active_storage/variant.rb b/lib/active_storage/variant.rb
index 62262c7790..3053f44211 100644
--- a/lib/active_storage/variant.rb
+++ b/lib/active_storage/variant.rb
@@ -27,7 +27,7 @@ class ActiveStorage::Variant
 
   def url(expires_in: 5.minutes, disposition: :inline)
     perform unless exist?
-    service.url key, expires_in: expires_in, disposition: disposition, filename: blob.filename
+    service.url blob_variant_key, expires_in: expires_in, disposition: disposition, filename: blob.filename
   end
 
   def key
@@ -35,6 +35,10 @@ class ActiveStorage::Variant
   end
 
   private
+    def exist?
+      service.exist?(blob_variant_key)
+    end
+
     def perform
       upload_variant transform(download_blob)
     end
@@ -44,7 +48,11 @@ class ActiveStorage::Variant
     end
 
     def upload_variant(variation)
-      service.upload key, variation
+      service.upload blob_variant_key, variation
+    end
+
+    def blob_variant_key
+      "variants/#{blob.key}/#{key}"
     end
 
     def transform(io)
-- 
cgit v1.2.3


From dda013050fe559e2e9432ae836c1239eac48fbce Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@loudthinking.com>
Date: Thu, 20 Jul 2017 14:06:08 -0500
Subject: Use the direct accessor

---
 test/variation_test.rb | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/test/variation_test.rb b/test/variation_test.rb
index 3b05095292..bc47244468 100644
--- a/test/variation_test.rb
+++ b/test/variation_test.rb
@@ -7,9 +7,7 @@ class ActiveStorage::VariationTest < ActiveSupport::TestCase
     blob = ActiveStorage::Blob.create_after_upload! \
       io: File.open(File.expand_path("../fixtures/files/racecar.jpg", __FILE__)), filename: "racecar.jpg", content_type: "image/jpeg"
 
-    variation_key = ActiveStorage::Variant.encode_key(resize: "500x500")
-
-    variant = ActiveStorage::Variant.lookup(blob_key: blob.key, variation_key: variation_key)
+    variant = blob.variant(resize: "100x100")
 
     assert_match /racecar.jpg/, variant.url
   end
-- 
cgit v1.2.3


From 1a9026b485b9b1da0f34c526d4c901406074c508 Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@loudthinking.com>
Date: Thu, 20 Jul 2017 17:33:31 -0500
Subject: Extract routes.rb to engine location for auto configuration

---
 config/routes.rb             | 13 +++++++++++++
 lib/active_storage/engine.rb | 11 -----------
 lib/active_storage/routes.rb |  3 ---
 test/test_helper.rb          | 11 -----------
 4 files changed, 13 insertions(+), 25 deletions(-)
 create mode 100644 config/routes.rb
 delete mode 100644 lib/active_storage/routes.rb

diff --git a/config/routes.rb b/config/routes.rb
new file mode 100644
index 0000000000..9057eadc8a
--- /dev/null
+++ b/config/routes.rb
@@ -0,0 +1,13 @@
+Rails.application.routes.draw do
+  get  "/rails/active_storage/disk/:encoded_key/*filename" => "active_storage/disk#show", as: :rails_disk_blob
+  get  "/rails/active_storage/variants/:encoded_blob_key/:encoded_variant_key/*filename" => "active_storage/variants#show", as: :rails_blob_variant
+  post "/rails/active_storage/direct_uploads" => "active_storage/direct_uploads#create", as: :rails_direct_uploads
+
+  resolve 'ActiveStorage::Variant' do |variant|
+    encoded_blob_key    = ActiveStorage::VerifiedKeyWithExpiration.encode(variant.blob.key)
+    encoded_variant_key = ActiveStorage::Variant.encode_key(variant.variation)
+    filename            = variant.blob.filename
+
+    route_for(:rails_blob_variant, encoded_blob_key, encoded_variant_key, filename)
+  end
+end
diff --git a/lib/active_storage/engine.rb b/lib/active_storage/engine.rb
index 8918b179e0..b04925a9fd 100644
--- a/lib/active_storage/engine.rb
+++ b/lib/active_storage/engine.rb
@@ -14,17 +14,6 @@ module ActiveStorage
       end
     end
 
-    initializer "active_storage.routes" do
-      require "active_storage/disk_controller"
-      require "active_storage/direct_uploads_controller"
-
-      config.after_initialize do |app|
-        app.routes.prepend do
-          eval(File.read(File.expand_path("../routes.rb", __FILE__)))
-        end
-      end
-    end
-
     initializer "active_storage.attached" do
       require "active_storage/attached"
 
diff --git a/lib/active_storage/routes.rb b/lib/active_storage/routes.rb
deleted file mode 100644
index fade234ad3..0000000000
--- a/lib/active_storage/routes.rb
+++ /dev/null
@@ -1,3 +0,0 @@
-get  "/rails/active_storage/disk/:encoded_key/*filename" => "active_storage/disk#show", as: :rails_disk_blob
-get  "/rails/active_storage/variants/:encoded_key/:encoded_transformation/*filename" => "active_storage/controllers/variants#show", as: :rails_blob_variant
-post "/rails/active_storage/direct_uploads" => "active_storage/direct_uploads#create", as: :rails_direct_uploads
diff --git a/test/test_helper.rb b/test/test_helper.rb
index 878ce8391c..6081fc1bcf 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -34,17 +34,6 @@ class ActiveSupport::TestCase
     end
 end
 
-require "action_controller"
-require "action_controller/test_case"
-
-class ActionController::TestCase
-  Routes = ActionDispatch::Routing::RouteSet.new.tap do |routes|
-    routes.draw do
-      eval(File.read(File.expand_path("../../lib/active_storage/routes.rb", __FILE__)))
-    end
-  end
-end
-
 require "active_storage/attached"
 ActiveRecord::Base.send :extend, ActiveStorage::Attached::Macros
 
-- 
cgit v1.2.3


From 1c85eecee02ebf0c0148de807fbb1a9e9573af8a Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@loudthinking.com>
Date: Thu, 20 Jul 2017 17:34:13 -0500
Subject: Move controllers to default engine location for auto loading

---
 Rakefile                                           |  1 +
 app/controllers/active_storage/disk_controller.rb  | 38 ++++++++++++++++++++++
 .../active_storage/variants_controller.rb          | 22 +++++++++++++
 lib/active_storage/direct_uploads_controller.rb    | 14 --------
 lib/active_storage/disk_controller.rb              | 38 ----------------------
 5 files changed, 61 insertions(+), 52 deletions(-)
 create mode 100644 app/controllers/active_storage/disk_controller.rb
 create mode 100644 app/controllers/active_storage/variants_controller.rb
 delete mode 100644 lib/active_storage/direct_uploads_controller.rb
 delete mode 100644 lib/active_storage/disk_controller.rb

diff --git a/Rakefile b/Rakefile
index f0baf50163..a41e07f373 100644
--- a/Rakefile
+++ b/Rakefile
@@ -3,6 +3,7 @@ require "bundler/gem_tasks"
 require "rake/testtask"
 
 Rake::TestTask.new do |test|
+  test.libs << "app/controllers"
   test.libs << "test"
   test.test_files = FileList["test/**/*_test.rb"]
   test.warning = false
diff --git a/app/controllers/active_storage/disk_controller.rb b/app/controllers/active_storage/disk_controller.rb
new file mode 100644
index 0000000000..16a295d00d
--- /dev/null
+++ b/app/controllers/active_storage/disk_controller.rb
@@ -0,0 +1,38 @@
+require "action_controller"
+require "active_storage/blob"
+require "active_storage/verified_key_with_expiration"
+
+require "active_support/core_ext/object/inclusion"
+
+# This controller is a wrapper around local file downloading. It allows you to
+# make abstraction of the URL generation logic and to serve files with expiry
+# if you are using the +Disk+ service.
+#
+# By default, mounting the Active Storage engine inside your application will
+# define a +/rails/blobs/:encoded_key/*filename+ route that will reference this
+# controller's +show+ action and will be used to serve local files.
+#
+# A URL for an attachment can be generated through its +#url+ method, that
+# will use the aforementioned route.
+class ActiveStorage::DiskController < ActionController::Base
+  def show
+    if key = decode_verified_key
+      blob = ActiveStorage::Blob.find_by!(key: key)
+
+      if stale?(etag: blob.checksum)
+        send_data blob.download, filename: blob.filename, type: blob.content_type, disposition: disposition_param
+      end
+    else
+      head :not_found
+    end
+  end
+
+  private
+    def decode_verified_key
+      ActiveStorage::VerifiedKeyWithExpiration.decode(params[:encoded_key])
+    end
+
+    def disposition_param
+      params[:disposition].presence_in(%w( inline attachment )) || "inline"
+    end
+end
diff --git a/app/controllers/active_storage/variants_controller.rb b/app/controllers/active_storage/variants_controller.rb
new file mode 100644
index 0000000000..05685dca17
--- /dev/null
+++ b/app/controllers/active_storage/variants_controller.rb
@@ -0,0 +1,22 @@
+class ActiveStorage::VariantsController < ActionController::Base
+  def show
+    if blob_key = decode_verified_blob_key
+      redirect_to processed_variant_for(blob_key).url(disposition: disposition_param)
+    else
+      head :not_found
+    end
+  end
+
+  private
+    def decode_verified_blob_key
+      ActiveStorage::VerifiedKeyWithExpiration.decode(params[:encoded_blob_key])
+    end
+
+    def processed_variant_for(blob_key)
+      ActiveStorage::Variant.find_or_process_by!(blob_key: blob_key, encoded_variant_key: params[:encoded_variant_key])
+    end
+
+    def disposition_param
+      params[:disposition].presence_in(%w( inline attachment )) || 'inline'
+    end
+end
diff --git a/lib/active_storage/direct_uploads_controller.rb b/lib/active_storage/direct_uploads_controller.rb
deleted file mode 100644
index 99ff27f903..0000000000
--- a/lib/active_storage/direct_uploads_controller.rb
+++ /dev/null
@@ -1,14 +0,0 @@
-require "action_controller"
-require "active_storage/blob"
-
-class ActiveStorage::DirectUploadsController < ActionController::Base
-  def create
-    blob = ActiveStorage::Blob.create_before_direct_upload!(blob_args)
-    render json: { url: blob.url_for_direct_upload, sgid: blob.to_sgid.to_param }
-  end
-
-  private
-    def blob_args
-      params.require(:blob).permit(:filename, :byte_size, :checksum, :content_type, :metadata).to_h.symbolize_keys
-    end
-end
diff --git a/lib/active_storage/disk_controller.rb b/lib/active_storage/disk_controller.rb
deleted file mode 100644
index 16a295d00d..0000000000
--- a/lib/active_storage/disk_controller.rb
+++ /dev/null
@@ -1,38 +0,0 @@
-require "action_controller"
-require "active_storage/blob"
-require "active_storage/verified_key_with_expiration"
-
-require "active_support/core_ext/object/inclusion"
-
-# This controller is a wrapper around local file downloading. It allows you to
-# make abstraction of the URL generation logic and to serve files with expiry
-# if you are using the +Disk+ service.
-#
-# By default, mounting the Active Storage engine inside your application will
-# define a +/rails/blobs/:encoded_key/*filename+ route that will reference this
-# controller's +show+ action and will be used to serve local files.
-#
-# A URL for an attachment can be generated through its +#url+ method, that
-# will use the aforementioned route.
-class ActiveStorage::DiskController < ActionController::Base
-  def show
-    if key = decode_verified_key
-      blob = ActiveStorage::Blob.find_by!(key: key)
-
-      if stale?(etag: blob.checksum)
-        send_data blob.download, filename: blob.filename, type: blob.content_type, disposition: disposition_param
-      end
-    else
-      head :not_found
-    end
-  end
-
-  private
-    def decode_verified_key
-      ActiveStorage::VerifiedKeyWithExpiration.decode(params[:encoded_key])
-    end
-
-    def disposition_param
-      params[:disposition].presence_in(%w( inline attachment )) || "inline"
-    end
-end
-- 
cgit v1.2.3


From 6c2cef21ce67f83bff45ce76c0370b03be11451f Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@loudthinking.com>
Date: Thu, 20 Jul 2017 17:34:32 -0500
Subject: Fix-up variants controller

---
 .../active_storage/direct_uploads_controller.rb    | 11 +++++++++++
 .../controllers/variants_controller.rb             | 22 ----------------------
 2 files changed, 11 insertions(+), 22 deletions(-)
 create mode 100644 app/controllers/active_storage/direct_uploads_controller.rb
 delete mode 100644 lib/active_storage/controllers/variants_controller.rb

diff --git a/app/controllers/active_storage/direct_uploads_controller.rb b/app/controllers/active_storage/direct_uploads_controller.rb
new file mode 100644
index 0000000000..dccd864e8d
--- /dev/null
+++ b/app/controllers/active_storage/direct_uploads_controller.rb
@@ -0,0 +1,11 @@
+class ActiveStorage::DirectUploadsController < ActionController::Base
+  def create
+    blob = ActiveStorage::Blob.create_before_direct_upload!(blob_args)
+    render json: { url: blob.url_for_direct_upload, sgid: blob.to_sgid.to_param }
+  end
+
+  private
+    def blob_args
+      params.require(:blob).permit(:filename, :byte_size, :checksum, :content_type, :metadata).to_h.symbolize_keys
+    end
+end
diff --git a/lib/active_storage/controllers/variants_controller.rb b/lib/active_storage/controllers/variants_controller.rb
deleted file mode 100644
index 094f94e706..0000000000
--- a/lib/active_storage/controllers/variants_controller.rb
+++ /dev/null
@@ -1,22 +0,0 @@
-require "action_controller"
-require "active_storage/blob"
-
-class ActiveStorage::Controllers::VariantsController < ActionController::Base
-  def show
-    if blob_key = decode_verified_key
-      variant = ActiveStorage::Variant.find_or_create_by(blob_key: blob_key, variation_key: params[:variation_key])
-      redirect_to variant.url
-    else
-      head :not_found
-    end
-  end
-
-  private
-    def decode_verified_key
-      ActiveStorage::VerifiedKeyWithExpiration.decode(params[:encoded_key])
-    end
-
-    def disposition_param
-      params[:disposition].presence_in(%w( inline attachment )) || 'inline'
-    end
-end
-- 
cgit v1.2.3


From af999681122bf583b6644974ba2033453935fd6d Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@loudthinking.com>
Date: Thu, 20 Jul 2017 17:35:15 -0500
Subject: Make processing an explicit step

---
 lib/active_storage/variant.rb | 12 ++++++++----
 test/variation_test.rb        |  4 +---
 2 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/lib/active_storage/variant.rb b/lib/active_storage/variant.rb
index 3053f44211..a07735eb57 100644
--- a/lib/active_storage/variant.rb
+++ b/lib/active_storage/variant.rb
@@ -13,8 +13,8 @@ class ActiveStorage::Variant
   attr_reader :blob, :variation
   delegate :service, to: :blob
 
-  def self.find_or_create_by(blob_key:, variation_key:)
-    new ActiveStorage::Blob.find_by!(key: blob_key), variation: verifier.verify(variation_key)
+  def self.find_or_process_by!(blob_key:, encoded_variant_key:)
+    new(ActiveStorage::Blob.find_by!(key: blob_key), variation: verifier.verify(encoded_variant_key)).processed
   end
 
   def self.encode_key(variation)
@@ -25,8 +25,12 @@ class ActiveStorage::Variant
     @blob, @variation = blob, variation
   end
 
+  def processed
+    process unless exist?
+    self
+  end
+
   def url(expires_in: 5.minutes, disposition: :inline)
-    perform unless exist?
     service.url blob_variant_key, expires_in: expires_in, disposition: disposition, filename: blob.filename
   end
 
@@ -39,7 +43,7 @@ class ActiveStorage::Variant
       service.exist?(blob_variant_key)
     end
 
-    def perform
+    def process
       upload_variant transform(download_blob)
     end
 
diff --git a/test/variation_test.rb b/test/variation_test.rb
index bc47244468..8e569f908c 100644
--- a/test/variation_test.rb
+++ b/test/variation_test.rb
@@ -7,8 +7,6 @@ class ActiveStorage::VariationTest < ActiveSupport::TestCase
     blob = ActiveStorage::Blob.create_after_upload! \
       io: File.open(File.expand_path("../fixtures/files/racecar.jpg", __FILE__)), filename: "racecar.jpg", content_type: "image/jpeg"
 
-    variant = blob.variant(resize: "100x100")
-
-    assert_match /racecar.jpg/, variant.url
+    assert_match /racecar.jpg/, blob.variant(resize: "100x100").processed.url
   end
 end
-- 
cgit v1.2.3


From a968e3c3c75df3f209275d31eb0bd4ed6effd51e Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@loudthinking.com>
Date: Thu, 20 Jul 2017 17:35:23 -0500
Subject: Consistent naming

---
 lib/active_storage/variant.rb | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/active_storage/variant.rb b/lib/active_storage/variant.rb
index a07735eb57..658fb2f5bd 100644
--- a/lib/active_storage/variant.rb
+++ b/lib/active_storage/variant.rb
@@ -51,8 +51,8 @@ class ActiveStorage::Variant
       service.download(blob.key)
     end
 
-    def upload_variant(variation)
-      service.upload blob_variant_key, variation
+    def upload_variant(variant)
+      service.upload blob_variant_key, variant
     end
 
     def blob_variant_key
-- 
cgit v1.2.3


From beb60b9c3a3f1f51d10fa800b967402d79ffcf28 Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@loudthinking.com>
Date: Thu, 20 Jul 2017 17:35:41 -0500
Subject: True is the same as no arguments

---
 lib/active_storage/variant.rb | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/lib/active_storage/variant.rb b/lib/active_storage/variant.rb
index 658fb2f5bd..7fcd3924f4 100644
--- a/lib/active_storage/variant.rb
+++ b/lib/active_storage/variant.rb
@@ -64,10 +64,11 @@ class ActiveStorage::Variant
         MiniMagick::Image.read(io).tap { |transforming_image|
           variation.each do |(method, argument)|
             if method = allowed_transformational_method(method.to_sym)
-              if argument.present?
-                transforming_image.public_send(method, argument)
-              else
+              if argument.blank? || argument == true
                 transforming_image.public_send(method)
+              else
+                # FIXME: Consider whitelisting allowed arguments as well?
+                transforming_image.public_send(method, argument)
               end
             end
           end
-- 
cgit v1.2.3


From cbe89319de0d2eda8ee53ab7c9d3bc92751deeb4 Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@loudthinking.com>
Date: Fri, 21 Jul 2017 12:35:00 -0500
Subject: Better naming

---
 lib/active_storage/variant.rb | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/lib/active_storage/variant.rb b/lib/active_storage/variant.rb
index 7fcd3924f4..4145ee644d 100644
--- a/lib/active_storage/variant.rb
+++ b/lib/active_storage/variant.rb
@@ -26,7 +26,7 @@ class ActiveStorage::Variant
   end
 
   def processed
-    process unless exist?
+    process unless processed?
     self
   end
 
@@ -38,8 +38,9 @@ class ActiveStorage::Variant
     verifier.generate(variation)
   end
 
+
   private
-    def exist?
+    def processed?
       service.exist?(blob_variant_key)
     end
 
-- 
cgit v1.2.3


From 438d5cc48e92345f000f51bc0780b543b3087846 Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@loudthinking.com>
Date: Fri, 21 Jul 2017 15:49:48 -0500
Subject: Accept that this is a full-Rails engine

---
 Gemfile.lock          | 50 +++++++++++++++++++++++++++++++++++++++++++++-----
 activestorage.gemspec |  5 +----
 2 files changed, 46 insertions(+), 9 deletions(-)

diff --git a/Gemfile.lock b/Gemfile.lock
index 8fe836eb70..e18acab95b 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -2,6 +2,16 @@ GIT
   remote: https://github.com/rails/rails.git
   revision: 5c16dd35a23f75038baf1527143ee44accf081ff
   specs:
+    actioncable (5.2.0.alpha)
+      actionpack (= 5.2.0.alpha)
+      nio4r (~> 2.0)
+      websocket-driver (~> 0.6.1)
+    actionmailer (5.2.0.alpha)
+      actionpack (= 5.2.0.alpha)
+      actionview (= 5.2.0.alpha)
+      activejob (= 5.2.0.alpha)
+      mail (~> 2.5, >= 2.5.4)
+      rails-dom-testing (~> 2.0)
     actionpack (5.2.0.alpha)
       actionview (= 5.2.0.alpha)
       activesupport (= 5.2.0.alpha)
@@ -29,15 +39,30 @@ GIT
       i18n (~> 0.7)
       minitest (~> 5.1)
       tzinfo (~> 1.1)
+    rails (5.2.0.alpha)
+      actioncable (= 5.2.0.alpha)
+      actionmailer (= 5.2.0.alpha)
+      actionpack (= 5.2.0.alpha)
+      actionview (= 5.2.0.alpha)
+      activejob (= 5.2.0.alpha)
+      activemodel (= 5.2.0.alpha)
+      activerecord (= 5.2.0.alpha)
+      activesupport (= 5.2.0.alpha)
+      bundler (>= 1.3.0)
+      railties (= 5.2.0.alpha)
+      sprockets-rails (>= 2.0.0)
+    railties (5.2.0.alpha)
+      actionpack (= 5.2.0.alpha)
+      activesupport (= 5.2.0.alpha)
+      method_source
+      rake (>= 0.8.7)
+      thor (>= 0.18.1, < 2.0)
 
 PATH
   remote: .
   specs:
     activestorage (0.1)
-      actionpack (>= 5.2.0.alpha)
-      activejob (>= 5.2.0.alpha)
-      activerecord (>= 5.2.0.alpha)
-      activesupport (>= 5.2.0.alpha)
+      rails (>= 5.2.0.alpha)
 
 GEM
   remote: https://rubygems.org/
@@ -101,7 +126,10 @@ GEM
       multi_json (~> 1.10)
     loofah (2.0.3)
       nokogiri (>= 1.5.9)
+    mail (2.6.5)
+      mime-types (>= 1.16, < 4)
     memoist (0.16.0)
+    method_source (0.8.2)
     mime-types (3.1)
       mime-types-data (~> 3.2015)
     mime-types-data (3.2016.0521)
@@ -111,6 +139,7 @@ GEM
     multi_json (1.12.1)
     multi_xml (0.6.0)
     multipart-post (2.0.0)
+    nio4r (2.1.0)
     nokogiri (1.8.0)
       mini_portile2 (~> 2.2.0)
     os (0.9.6)
@@ -148,12 +177,23 @@ GEM
       faraday (~> 0.9)
       jwt (~> 1.5)
       multi_json (~> 1.10)
+    sprockets (3.7.1)
+      concurrent-ruby (~> 1.0)
+      rack (> 1, < 3)
+    sprockets-rails (3.2.0)
+      actionpack (>= 4.0)
+      activesupport (>= 4.0)
+      sprockets (>= 3.0.0)
     sqlite3 (1.3.13)
+    thor (0.19.4)
     thread_safe (0.3.6)
     tzinfo (1.2.3)
       thread_safe (~> 0.1)
     uber (0.1.0)
     unicode-display_width (1.3.0)
+    websocket-driver (0.6.5)
+      websocket-extensions (>= 0.1.0)
+    websocket-extensions (0.1.2)
 
 PLATFORMS
   ruby
@@ -175,4 +215,4 @@ DEPENDENCIES
   sqlite3
 
 BUNDLED WITH
-   1.15.1
+   1.15.2
diff --git a/activestorage.gemspec b/activestorage.gemspec
index 884d3287e6..9546b60783 100644
--- a/activestorage.gemspec
+++ b/activestorage.gemspec
@@ -9,10 +9,7 @@ Gem::Specification.new do |s|
 
   s.required_ruby_version = ">= 2.3.0"
 
-  s.add_dependency "activesupport", ">= 5.2.0.alpha"
-  s.add_dependency "activerecord", ">= 5.2.0.alpha"
-  s.add_dependency "actionpack", ">= 5.2.0.alpha"
-  s.add_dependency "activejob", ">= 5.2.0.alpha"
+  s.add_dependency "rails", ">= 5.2.0.alpha"
 
   s.add_development_dependency "bundler", "~> 1.15"
 
-- 
cgit v1.2.3


From 9ac31a3c8a7bf996ef2614a2dc83c1d345c78b35 Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@loudthinking.com>
Date: Fri, 21 Jul 2017 15:50:19 -0500
Subject: Mount routes on the engine

---
 config/routes.rb | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/config/routes.rb b/config/routes.rb
index 9057eadc8a..ad54b178fe 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -1,4 +1,4 @@
-Rails.application.routes.draw do
+ActiveStorage::Engine.routes.draw do
   get  "/rails/active_storage/disk/:encoded_key/*filename" => "active_storage/disk#show", as: :rails_disk_blob
   get  "/rails/active_storage/variants/:encoded_blob_key/:encoded_variant_key/*filename" => "active_storage/variants#show", as: :rails_blob_variant
   post "/rails/active_storage/direct_uploads" => "active_storage/direct_uploads#create", as: :rails_direct_uploads
-- 
cgit v1.2.3


From 0c47740d858cb04c7165bce411584c3b05d155b6 Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@loudthinking.com>
Date: Fri, 21 Jul 2017 15:50:36 -0500
Subject: Hacky way to mount routes for engine controller tests

---
 test/test_helper.rb | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/test/test_helper.rb b/test/test_helper.rb
index 6081fc1bcf..af379ad35a 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -34,6 +34,17 @@ class ActiveSupport::TestCase
     end
 end
 
+require "action_controller"
+require "action_controller/test_case"
+class ActionController::TestCase
+  Routes = ActionDispatch::Routing::RouteSet.new.tap do |routes|
+    routes.draw do
+      # FIXME: Hacky way to avoid having to instantiate the real engine
+      eval(File.readlines(File.expand_path("../../config/routes.rb", __FILE__)).slice(1..-2).join("\n"))
+    end
+  end
+end
+
 require "active_storage/attached"
 ActiveRecord::Base.send :extend, ActiveStorage::Attached::Macros
 
-- 
cgit v1.2.3


From 7f4111185ca6286adbe0ffc1346d416c5fa7dfd3 Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@loudthinking.com>
Date: Fri, 21 Jul 2017 15:51:31 -0500
Subject: Extract variation value object

---
 lib/active_storage/blob.rb      |  8 +++--
 lib/active_storage/engine.rb    |  2 +-
 lib/active_storage/variant.rb   | 66 ++++++++---------------------------------
 lib/active_storage/variation.rb | 53 +++++++++++++++++++++++++++++++++
 test/test_helper.rb             |  5 ++--
 test/variation_test.rb          | 15 +++++++---
 6 files changed, 84 insertions(+), 65 deletions(-)
 create mode 100644 lib/active_storage/variation.rb

diff --git a/lib/active_storage/blob.rb b/lib/active_storage/blob.rb
index a9d9b8771c..6bd3941cd8 100644
--- a/lib/active_storage/blob.rb
+++ b/lib/active_storage/blob.rb
@@ -32,8 +32,9 @@ class ActiveStorage::Blob < ActiveRecord::Base
     end
   end
 
-  # We can't wait until the record is first saved to have a key for it
+
   def key
+    # We can't wait until the record is first saved to have a key for it
     self[:key] ||= self.class.generate_unique_secure_token
   end
 
@@ -41,10 +42,11 @@ class ActiveStorage::Blob < ActiveRecord::Base
     ActiveStorage::Filename.new(self[:filename])
   end
 
-  def variant(variation)
-    ActiveStorage::Variant.new(self, variation: variation)
+  def variant(transformations)
+    ActiveStorage::Variant.new(self, ActiveStorage::Variation.new(transformations))
   end
 
+
   def url(expires_in: 5.minutes, disposition: :inline)
     service.url key, expires_in: expires_in, disposition: disposition, filename: filename
   end
diff --git a/lib/active_storage/engine.rb b/lib/active_storage/engine.rb
index b04925a9fd..11227a4e04 100644
--- a/lib/active_storage/engine.rb
+++ b/lib/active_storage/engine.rb
@@ -28,7 +28,7 @@ module ActiveStorage
 
       config.after_initialize do |app|
         ActiveStorage::VerifiedKeyWithExpiration.verifier = \
-        ActiveStorage::Variant.verifier = \
+        ActiveStorage::Variation.verifier = \
           Rails.application.message_verifier('ActiveStorage')
       end
     end
diff --git a/lib/active_storage/variant.rb b/lib/active_storage/variant.rb
index 4145ee644d..8be51eba92 100644
--- a/lib/active_storage/variant.rb
+++ b/lib/active_storage/variant.rb
@@ -1,82 +1,40 @@
 require "active_storage/blob"
-require "active_support/core_ext/object/inclusion"
 require "mini_magick"
 
 class ActiveStorage::Variant
-  class_attribute :verifier
-
-  ALLOWED_TRANSFORMATIONS = %i(
-    resize rotate format flip fill monochrome orient quality roll scale sharpen shave shear size thumbnail
-    transparent transpose transverse trim background bordercolor compress crop
-  )
-
   attr_reader :blob, :variation
   delegate :service, to: :blob
 
-  def self.find_or_process_by!(blob_key:, encoded_variant_key:)
-    new(ActiveStorage::Blob.find_by!(key: blob_key), variation: verifier.verify(encoded_variant_key)).processed
-  end
-
-  def self.encode_key(variation)
-    verifier.generate(variation)
+  class << self
+    def find_or_process_by!(blob_key:, variation_key:)
+      new(ActiveStorage::Blob.find_by!(key: blob_key), variation: ActiveStorage::Variation.decode(variation_key)).processed
+    end
   end
 
-  def initialize(blob, variation:)
+  def initialize(blob, variation)
     @blob, @variation = blob, variation
   end
 
   def processed
-    process unless processed?
+    process unless service.exist?(key)
     self
   end
 
-  def url(expires_in: 5.minutes, disposition: :inline)
-    service.url blob_variant_key, expires_in: expires_in, disposition: disposition, filename: blob.filename
+  def key
+    "variants/#{blob.key}/#{variation.key}"
   end
 
-  def key
-    verifier.generate(variation)
+  def url(expires_in: 5.minutes, disposition: :inline)
+    service.url key, expires_in: expires_in, disposition: disposition, filename: blob.filename
   end
 
 
   private
-    def processed?
-      service.exist?(blob_variant_key)
-    end
-
     def process
-      upload_variant transform(download_blob)
-    end
-
-    def download_blob
-      service.download(blob.key)
-    end
-
-    def upload_variant(variant)
-      service.upload blob_variant_key, variant
-    end
-
-    def blob_variant_key
-      "variants/#{blob.key}/#{key}"
+      service.upload key, transform(service.download(blob.key))
     end
 
     def transform(io)
-      File.open \
-        MiniMagick::Image.read(io).tap { |transforming_image|
-          variation.each do |(method, argument)|
-            if method = allowed_transformational_method(method.to_sym)
-              if argument.blank? || argument == true
-                transforming_image.public_send(method)
-              else
-                # FIXME: Consider whitelisting allowed arguments as well?
-                transforming_image.public_send(method, argument)
-              end
-            end
-          end
-        }.path
-    end
-
-    def allowed_transformational_method(method)
-      method.presence_in(ALLOWED_TRANSFORMATIONS)
+      File.open MiniMagick::Image.read(io).tap { |image| variation.transform(image) }.path
     end
 end
diff --git a/lib/active_storage/variation.rb b/lib/active_storage/variation.rb
new file mode 100644
index 0000000000..abff288ac1
--- /dev/null
+++ b/lib/active_storage/variation.rb
@@ -0,0 +1,53 @@
+require "active_support/core_ext/object/inclusion"
+
+# A set of transformations that can be applied to a blob to create a variant.
+class ActiveStorage::Variation
+  class_attribute :verifier
+
+  ALLOWED_TRANSFORMATIONS = %i(
+    resize rotate format flip fill monochrome orient quality roll scale sharpen shave shear size thumbnail
+    transparent transpose transverse trim background bordercolor compress crop
+  )
+
+  attr_reader :transformations
+
+  class << self
+    def decode(key)
+      new verifier.verify(key)
+    end
+    
+    def encode(transformations)
+      verifier.generate(transformations)
+    end
+  end
+
+  def initialize(transformations)
+    @transformations = transformations
+  end
+
+  def transform(image)
+    transformations.each do |(method, argument)|
+      next unless eligible_transformation?(method)
+
+      if eligible_argument?(argument)
+        image.public_send(method, argument)
+      else
+        image.public_send(method)
+      end
+    end
+  end
+
+  def key
+    self.class.encode(transformations)
+  end
+
+  private
+    def eligible_transformation?(method)
+      method.to_sym.in?(ALLOWED_TRANSFORMATIONS)
+    end
+
+    # FIXME: Consider whitelisting allowed arguments as well?
+    def eligible_argument?(argument)
+      argument.present? && argument != true
+    end
+end
diff --git a/test/test_helper.rb b/test/test_helper.rb
index af379ad35a..e98b6e0afc 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -15,7 +15,6 @@ rescue Errno::ENOENT
   {}
 end
 
-
 require "active_storage/service/disk_service"
 require "tmpdir"
 ActiveStorage::Blob.service = ActiveStorage::Service::DiskService.new(root: Dir.mktmpdir("active_storage_tests"))
@@ -24,8 +23,8 @@ ActiveStorage::Service.logger = ActiveSupport::Logger.new(STDOUT)
 require "active_storage/verified_key_with_expiration"
 ActiveStorage::VerifiedKeyWithExpiration.verifier = ActiveSupport::MessageVerifier.new("Testing")
 
-require "active_storage/variant"
-ActiveStorage::Variant.verifier = ActiveSupport::MessageVerifier.new("Testing")
+require "active_storage/variation"
+ActiveStorage::Variation.verifier = ActiveSupport::MessageVerifier.new("Testing")
 
 class ActiveSupport::TestCase
   private
diff --git a/test/variation_test.rb b/test/variation_test.rb
index 8e569f908c..d138682005 100644
--- a/test/variation_test.rb
+++ b/test/variation_test.rb
@@ -3,10 +3,17 @@ require "database/setup"
 require "active_storage/variant"
 
 class ActiveStorage::VariationTest < ActiveSupport::TestCase
-  test "square variation" do
-    blob = ActiveStorage::Blob.create_after_upload! \
-      io: File.open(File.expand_path("../fixtures/files/racecar.jpg", __FILE__)), filename: "racecar.jpg", content_type: "image/jpeg"
+  setup do
+    @blob = ActiveStorage::Blob.create_after_upload! \
+        filename: "racecar.jpg", content_type: "image/jpeg",
+        io: File.open(File.expand_path("../fixtures/files/racecar.jpg", __FILE__))
+  end
+
+  test "resized variation" do
+    assert_match /racecar.jpg/, @blob.variant(resize: "100x100").processed.url
+  end
 
-    assert_match /racecar.jpg/, blob.variant(resize: "100x100").processed.url
+  test "resized and monochrome variation" do
+    assert_match /racecar.jpg/, @blob.variant(resize: "100x100", monochrome: true).processed.url
   end
 end
-- 
cgit v1.2.3


From c6952638818213a2a475437bc93e60b4386ac02a Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@loudthinking.com>
Date: Fri, 21 Jul 2017 15:52:09 -0500
Subject: Precise naming

---
 test/variant_test.rb   | 19 +++++++++++++++++++
 test/variation_test.rb | 19 -------------------
 2 files changed, 19 insertions(+), 19 deletions(-)
 create mode 100644 test/variant_test.rb
 delete mode 100644 test/variation_test.rb

diff --git a/test/variant_test.rb b/test/variant_test.rb
new file mode 100644
index 0000000000..bc3a1fef90
--- /dev/null
+++ b/test/variant_test.rb
@@ -0,0 +1,19 @@
+require "test_helper"
+require "database/setup"
+require "active_storage/variant"
+
+class ActiveStorage::VariantTest < ActiveSupport::TestCase
+  setup do
+    @blob = ActiveStorage::Blob.create_after_upload! \
+        filename: "racecar.jpg", content_type: "image/jpeg",
+        io: File.open(File.expand_path("../fixtures/files/racecar.jpg", __FILE__))
+  end
+
+  test "resized variation" do
+    assert_match /racecar.jpg/, @blob.variant(resize: "100x100").processed.url
+  end
+
+  test "resized and monochrome variation" do
+    assert_match /racecar.jpg/, @blob.variant(resize: "100x100", monochrome: true).processed.url
+  end
+end
diff --git a/test/variation_test.rb b/test/variation_test.rb
deleted file mode 100644
index d138682005..0000000000
--- a/test/variation_test.rb
+++ /dev/null
@@ -1,19 +0,0 @@
-require "test_helper"
-require "database/setup"
-require "active_storage/variant"
-
-class ActiveStorage::VariationTest < ActiveSupport::TestCase
-  setup do
-    @blob = ActiveStorage::Blob.create_after_upload! \
-        filename: "racecar.jpg", content_type: "image/jpeg",
-        io: File.open(File.expand_path("../fixtures/files/racecar.jpg", __FILE__))
-  end
-
-  test "resized variation" do
-    assert_match /racecar.jpg/, @blob.variant(resize: "100x100").processed.url
-  end
-
-  test "resized and monochrome variation" do
-    assert_match /racecar.jpg/, @blob.variant(resize: "100x100", monochrome: true).processed.url
-  end
-end
-- 
cgit v1.2.3


From 67606dcdf52ae7f83e42a9872fdc545b02f227a2 Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@loudthinking.com>
Date: Fri, 21 Jul 2017 15:52:21 -0500
Subject: Over-indented

---
 test/variant_test.rb | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/test/variant_test.rb b/test/variant_test.rb
index bc3a1fef90..ee3bc5c0e5 100644
--- a/test/variant_test.rb
+++ b/test/variant_test.rb
@@ -5,8 +5,8 @@ require "active_storage/variant"
 class ActiveStorage::VariantTest < ActiveSupport::TestCase
   setup do
     @blob = ActiveStorage::Blob.create_after_upload! \
-        filename: "racecar.jpg", content_type: "image/jpeg",
-        io: File.open(File.expand_path("../fixtures/files/racecar.jpg", __FILE__))
+      filename: "racecar.jpg", content_type: "image/jpeg",
+      io: File.open(File.expand_path("../fixtures/files/racecar.jpg", __FILE__))
   end
 
   test "resized variation" do
-- 
cgit v1.2.3


From 796f8330ad441e93590a57521ef8fb80a030fb66 Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@loudthinking.com>
Date: Fri, 21 Jul 2017 16:12:29 -0500
Subject: Fix and test VariantsController

---
 .../active_storage/variants_controller.rb          |  5 ++++-
 config/routes.rb                                   | 10 ++++-----
 lib/active_storage/variant.rb                      |  6 ------
 test/controllers/variants_controller.rb            | 25 ++++++++++++++++++++++
 test/test_helper.rb                                |  2 ++
 5 files changed, 36 insertions(+), 12 deletions(-)
 create mode 100644 test/controllers/variants_controller.rb

diff --git a/app/controllers/active_storage/variants_controller.rb b/app/controllers/active_storage/variants_controller.rb
index 05685dca17..dde7e1458f 100644
--- a/app/controllers/active_storage/variants_controller.rb
+++ b/app/controllers/active_storage/variants_controller.rb
@@ -13,7 +13,10 @@ class ActiveStorage::VariantsController < ActionController::Base
     end
 
     def processed_variant_for(blob_key)
-      ActiveStorage::Variant.find_or_process_by!(blob_key: blob_key, encoded_variant_key: params[:encoded_variant_key])
+      ActiveStorage::Variant.new(
+        ActiveStorage::Blob.find_by!(key: blob_key),
+        ActiveStorage::Variation.decode(params[:variation_key])
+      ).processed
     end
 
     def disposition_param
diff --git a/config/routes.rb b/config/routes.rb
index ad54b178fe..bd0787180a 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -1,13 +1,13 @@
 ActiveStorage::Engine.routes.draw do
   get  "/rails/active_storage/disk/:encoded_key/*filename" => "active_storage/disk#show", as: :rails_disk_blob
-  get  "/rails/active_storage/variants/:encoded_blob_key/:encoded_variant_key/*filename" => "active_storage/variants#show", as: :rails_blob_variant
+  get  "/rails/active_storage/variants/:encoded_blob_key/:variation_key/*filename" => "active_storage/variants#show", as: :rails_blob_variant
   post "/rails/active_storage/direct_uploads" => "active_storage/direct_uploads#create", as: :rails_direct_uploads
 
   resolve 'ActiveStorage::Variant' do |variant|
-    encoded_blob_key    = ActiveStorage::VerifiedKeyWithExpiration.encode(variant.blob.key)
-    encoded_variant_key = ActiveStorage::Variant.encode_key(variant.variation)
-    filename            = variant.blob.filename
+    encoded_blob_key = ActiveStorage::VerifiedKeyWithExpiration.encode(variant.blob.key)
+    variantion_key   = ActiveStorage::Variation.encode(variant.variation)
+    filename         = variant.blob.filename
 
-    route_for(:rails_blob_variant, encoded_blob_key, encoded_variant_key, filename)
+    route_for(:rails_blob_variant, encoded_blob_key, variantion_key, filename)
   end
 end
diff --git a/lib/active_storage/variant.rb b/lib/active_storage/variant.rb
index 8be51eba92..ba2604eccf 100644
--- a/lib/active_storage/variant.rb
+++ b/lib/active_storage/variant.rb
@@ -5,12 +5,6 @@ class ActiveStorage::Variant
   attr_reader :blob, :variation
   delegate :service, to: :blob
 
-  class << self
-    def find_or_process_by!(blob_key:, variation_key:)
-      new(ActiveStorage::Blob.find_by!(key: blob_key), variation: ActiveStorage::Variation.decode(variation_key)).processed
-    end
-  end
-
   def initialize(blob, variation)
     @blob, @variation = blob, variation
   end
diff --git a/test/controllers/variants_controller.rb b/test/controllers/variants_controller.rb
new file mode 100644
index 0000000000..132d93a3cf
--- /dev/null
+++ b/test/controllers/variants_controller.rb
@@ -0,0 +1,25 @@
+require "test_helper"
+require "database/setup"
+
+require "active_storage/variants_controller"
+require "active_storage/verified_key_with_expiration"
+
+class ActiveStorage::VariantsControllerTest < ActionController::TestCase
+  setup do
+    @blob = ActiveStorage::Blob.create_after_upload! \
+      filename: "racecar.jpg", content_type: "image/jpeg",
+      io: File.open(File.expand_path("../../fixtures/files/racecar.jpg", __FILE__))
+
+    @routes = Routes
+    @controller = ActiveStorage::VariantsController.new
+  end
+
+  test "showing variant inline" do
+    get :show, params: {
+      filename: @blob.filename,
+      encoded_blob_key: ActiveStorage::VerifiedKeyWithExpiration.encode(@blob.key, expires_in: 5.minutes),
+      variation_key: ActiveStorage::Variation.encode(resize: "100x100") }
+
+    assert_redirected_to /racecar.jpg\?disposition=inline/
+  end
+end
diff --git a/test/test_helper.rb b/test/test_helper.rb
index e98b6e0afc..7aa7b50bf3 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -1,3 +1,5 @@
+$LOAD_PATH << File.expand_path("../../app/controllers", __FILE__)
+
 require "bundler/setup"
 require "active_support"
 require "active_support/test_case"
-- 
cgit v1.2.3


From dd3eced57622f256891ce97cdd0cf1feabef40c2 Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@loudthinking.com>
Date: Fri, 21 Jul 2017 16:24:39 -0500
Subject: Proper require

---
 lib/active_storage/engine.rb | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/active_storage/engine.rb b/lib/active_storage/engine.rb
index 11227a4e04..b32ae34516 100644
--- a/lib/active_storage/engine.rb
+++ b/lib/active_storage/engine.rb
@@ -24,7 +24,7 @@ module ActiveStorage
 
     initializer "active_storage.verifiers" do
       require "active_storage/verified_key_with_expiration"
-      require "active_storage/variant"
+      require "active_storage/variation"
 
       config.after_initialize do |app|
         ActiveStorage::VerifiedKeyWithExpiration.verifier = \
-- 
cgit v1.2.3


From c231a73b892e1fd2d4ae2e939fe36bee0238f919 Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@loudthinking.com>
Date: Fri, 21 Jul 2017 16:25:01 -0500
Subject: Provide directed URL as well as resolving

---
 config/routes.rb | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/config/routes.rb b/config/routes.rb
index bd0787180a..c376493199 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -1,13 +1,16 @@
 ActiveStorage::Engine.routes.draw do
   get  "/rails/active_storage/disk/:encoded_key/*filename" => "active_storage/disk#show", as: :rails_disk_blob
-  get  "/rails/active_storage/variants/:encoded_blob_key/:variation_key/*filename" => "active_storage/variants#show", as: :rails_blob_variant
   post "/rails/active_storage/direct_uploads" => "active_storage/direct_uploads#create", as: :rails_direct_uploads
 
-  resolve 'ActiveStorage::Variant' do |variant|
+  get  "/rails/active_storage/variants/:encoded_blob_key/:variation_key/*filename" => "active_storage/variants#show", as: :rails_blob_variation
+
+  direct :rails_variant do |variant|
     encoded_blob_key = ActiveStorage::VerifiedKeyWithExpiration.encode(variant.blob.key)
-    variantion_key   = ActiveStorage::Variation.encode(variant.variation)
+    variation_key    = variant.variation.key
     filename         = variant.blob.filename
 
-    route_for(:rails_blob_variant, encoded_blob_key, variantion_key, filename)
+    route_for(:rails_blob_variation, encoded_blob_key, variation_key, filename)
   end
+
+  resolve 'ActiveStorage::Variant' { |variant| route_for(:rails_variant, variant) }
 end
-- 
cgit v1.2.3


From 39f9ef122dc011d08e0b8d76cad0112c2fa3665f Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@loudthinking.com>
Date: Fri, 21 Jul 2017 16:25:11 -0500
Subject: Actually we just want them mounted straight

---
 config/routes.rb | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/config/routes.rb b/config/routes.rb
index c376493199..ec4d954e81 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -1,4 +1,4 @@
-ActiveStorage::Engine.routes.draw do
+Rails.application.routes.draw do
   get  "/rails/active_storage/disk/:encoded_key/*filename" => "active_storage/disk#show", as: :rails_disk_blob
   post "/rails/active_storage/direct_uploads" => "active_storage/direct_uploads#create", as: :rails_direct_uploads
 
-- 
cgit v1.2.3


From b6fd579a7e97f1a3aee27d22e12784f7a6155799 Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@loudthinking.com>
Date: Fri, 21 Jul 2017 16:26:34 -0500
Subject: Fix parens after inline block

---
 config/routes.rb | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/config/routes.rb b/config/routes.rb
index ec4d954e81..d25f2c82f0 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -12,5 +12,5 @@ Rails.application.routes.draw do
     route_for(:rails_blob_variation, encoded_blob_key, variation_key, filename)
   end
 
-  resolve 'ActiveStorage::Variant' { |variant| route_for(:rails_variant, variant) }
+  resolve('ActiveStorage::Variant') { |variant| route_for(:rails_variant, variant) }
 end
-- 
cgit v1.2.3


From 08d84e225cca6772aa54dfb7123120fe1070ea30 Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@loudthinking.com>
Date: Fri, 21 Jul 2017 16:34:18 -0500
Subject: Extract test helper for image blob fixtures

---
 test/controllers/variants_controller.rb | 6 ++----
 test/test_helper.rb                     | 6 ++++++
 test/variant_test.rb                    | 4 +---
 3 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/test/controllers/variants_controller.rb b/test/controllers/variants_controller.rb
index 132d93a3cf..22f5ec1454 100644
--- a/test/controllers/variants_controller.rb
+++ b/test/controllers/variants_controller.rb
@@ -6,12 +6,10 @@ require "active_storage/verified_key_with_expiration"
 
 class ActiveStorage::VariantsControllerTest < ActionController::TestCase
   setup do
-    @blob = ActiveStorage::Blob.create_after_upload! \
-      filename: "racecar.jpg", content_type: "image/jpeg",
-      io: File.open(File.expand_path("../../fixtures/files/racecar.jpg", __FILE__))
-
     @routes = Routes
     @controller = ActiveStorage::VariantsController.new
+
+    @blob = create_image_blob filename: "racecar.jpg"
   end
 
   test "showing variant inline" do
diff --git a/test/test_helper.rb b/test/test_helper.rb
index 7aa7b50bf3..69ba76b9c4 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -33,6 +33,12 @@ class ActiveSupport::TestCase
     def create_blob(data: "Hello world!", filename: "hello.txt", content_type: "text/plain")
       ActiveStorage::Blob.create_after_upload! io: StringIO.new(data), filename: filename, content_type: content_type
     end
+
+    def create_image_blob(filename: "racecar.jpg", content_type: "image/jpeg")
+      ActiveStorage::Blob.create_after_upload! \
+        io: File.open(File.expand_path("../fixtures/files/#{filename}", __FILE__)),
+        filename: filename, content_type: content_type
+    end
 end
 
 require "action_controller"
diff --git a/test/variant_test.rb b/test/variant_test.rb
index ee3bc5c0e5..0368960fbf 100644
--- a/test/variant_test.rb
+++ b/test/variant_test.rb
@@ -4,9 +4,7 @@ require "active_storage/variant"
 
 class ActiveStorage::VariantTest < ActiveSupport::TestCase
   setup do
-    @blob = ActiveStorage::Blob.create_after_upload! \
-      filename: "racecar.jpg", content_type: "image/jpeg",
-      io: File.open(File.expand_path("../fixtures/files/racecar.jpg", __FILE__))
+    @blob = create_image_blob filename: "racecar.jpg"
   end
 
   test "resized variation" do
-- 
cgit v1.2.3


From fa33ec9e7decde0fc0ba3e2bd2b7fc9f06908065 Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@loudthinking.com>
Date: Fri, 21 Jul 2017 16:34:28 -0500
Subject: Anemic intro

---
 lib/active_storage/variant.rb | 1 +
 1 file changed, 1 insertion(+)

diff --git a/lib/active_storage/variant.rb b/lib/active_storage/variant.rb
index ba2604eccf..435033f980 100644
--- a/lib/active_storage/variant.rb
+++ b/lib/active_storage/variant.rb
@@ -1,6 +1,7 @@
 require "active_storage/blob"
 require "mini_magick"
 
+# Image blobs can have variants that are the result of a set of transformations applied to the original.
 class ActiveStorage::Variant
   attr_reader :blob, :variation
   delegate :service, to: :blob
-- 
cgit v1.2.3


From e9cf92cc399a169ec47496da198cfb984856000d Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@loudthinking.com>
Date: Fri, 21 Jul 2017 16:44:10 -0500
Subject: Test actual transformations

---
 test/fixtures/files/racecar-100x100-monochrome.jpg | Bin 0 -> 27586 bytes
 test/fixtures/files/racecar-100x100.jpg            | Bin 0 -> 29446 bytes
 test/variant_test.rb                               |  17 +++++++++++++++--
 3 files changed, 15 insertions(+), 2 deletions(-)
 create mode 100644 test/fixtures/files/racecar-100x100-monochrome.jpg
 create mode 100644 test/fixtures/files/racecar-100x100.jpg

diff --git a/test/fixtures/files/racecar-100x100-monochrome.jpg b/test/fixtures/files/racecar-100x100-monochrome.jpg
new file mode 100644
index 0000000000..39e683747e
Binary files /dev/null and b/test/fixtures/files/racecar-100x100-monochrome.jpg differ
diff --git a/test/fixtures/files/racecar-100x100.jpg b/test/fixtures/files/racecar-100x100.jpg
new file mode 100644
index 0000000000..2a515a4912
Binary files /dev/null and b/test/fixtures/files/racecar-100x100.jpg differ
diff --git a/test/variant_test.rb b/test/variant_test.rb
index 0368960fbf..e41842a80c 100644
--- a/test/variant_test.rb
+++ b/test/variant_test.rb
@@ -8,10 +8,23 @@ class ActiveStorage::VariantTest < ActiveSupport::TestCase
   end
 
   test "resized variation" do
-    assert_match /racecar.jpg/, @blob.variant(resize: "100x100").processed.url
+    variant = @blob.variant(resize: "100x100").processed
+
+    assert_match /racecar.jpg/, variant.url    
+    assert_same_image "racecar-100x100.jpg", variant    
   end
 
   test "resized and monochrome variation" do
-    assert_match /racecar.jpg/, @blob.variant(resize: "100x100", monochrome: true).processed.url
+    variant = @blob.variant(resize: "100x100", monochrome: true).processed
+
+    assert_match /racecar.jpg/, variant.url
+    assert_same_image "racecar-100x100-monochrome.jpg", variant    
   end
+
+  private
+    def assert_same_image(fixture_filename, variant)
+      assert_equal \
+        File.binread(File.expand_path("../fixtures/files/#{fixture_filename}", __FILE__)),
+        File.binread(variant.service.send(:path_for, variant.key))
+    end
 end
-- 
cgit v1.2.3


From f3b092a6e6f6d873e14ebe1e612028ef7ac15e4a Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@loudthinking.com>
Date: Fri, 21 Jul 2017 16:45:55 -0500
Subject: Test actual transformation via controller too

---
 test/controllers/variants_controller.rb | 1 +
 test/test_helper.rb                     | 6 ++++++
 test/variant_test.rb                    | 7 -------
 3 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/test/controllers/variants_controller.rb b/test/controllers/variants_controller.rb
index 22f5ec1454..6753584d4d 100644
--- a/test/controllers/variants_controller.rb
+++ b/test/controllers/variants_controller.rb
@@ -19,5 +19,6 @@ class ActiveStorage::VariantsControllerTest < ActionController::TestCase
       variation_key: ActiveStorage::Variation.encode(resize: "100x100") }
 
     assert_redirected_to /racecar.jpg\?disposition=inline/
+    assert_same_image "racecar-100x100.jpg", @blob.variant(resize: "100x100")
   end
 end
diff --git a/test/test_helper.rb b/test/test_helper.rb
index 69ba76b9c4..20b22049b3 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -39,6 +39,12 @@ class ActiveSupport::TestCase
         io: File.open(File.expand_path("../fixtures/files/#{filename}", __FILE__)),
         filename: filename, content_type: content_type
     end
+
+    def assert_same_image(fixture_filename, variant)
+      assert_equal \
+        File.binread(File.expand_path("../fixtures/files/#{fixture_filename}", __FILE__)),
+        File.binread(variant.service.send(:path_for, variant.key))
+    end
 end
 
 require "action_controller"
diff --git a/test/variant_test.rb b/test/variant_test.rb
index e41842a80c..5294b87135 100644
--- a/test/variant_test.rb
+++ b/test/variant_test.rb
@@ -20,11 +20,4 @@ class ActiveStorage::VariantTest < ActiveSupport::TestCase
     assert_match /racecar.jpg/, variant.url
     assert_same_image "racecar-100x100-monochrome.jpg", variant    
   end
-
-  private
-    def assert_same_image(fixture_filename, variant)
-      assert_equal \
-        File.binread(File.expand_path("../fixtures/files/#{fixture_filename}", __FILE__)),
-        File.binread(variant.service.send(:path_for, variant.key))
-    end
 end
-- 
cgit v1.2.3


From 2e9ff80e50fee0df6ea47d4d43a27c4505985b29 Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@loudthinking.com>
Date: Fri, 21 Jul 2017 16:49:00 -0500
Subject: Quick example of variants

---
 README.md | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/README.md b/README.md
index 625b960624..48a33f8b3d 100644
--- a/README.md
+++ b/README.md
@@ -63,6 +63,13 @@ class MessagesController < ApplicationController
 end
 ```
 
+Variation of image attachment:
+
+```erb
+<%# Hitting the variant URL will lazy transform the original blob and then redirect to its new service location %>
+<%= image_tag url_for(user.avatar.variant(resize: "100x100")) %>
+```
+
 ## Installation
 
 1. Add `require "active_storage"` to config/application.rb, after `require "rails/all"` line.
-- 
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From 6ac4fec964e67cf3d7dfbf7726bff9b05aca522c Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@loudthinking.com>
Date: Fri, 21 Jul 2017 16:50:23 -0500
Subject: Mention need for mini_magick with variants

---
 README.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/README.md b/README.md
index 69166664f6..b56999cae7 100644
--- a/README.md
+++ b/README.md
@@ -77,6 +77,7 @@ Variation of image attachment:
 3. Run `rails activestorage:install` to create needed directories, migrations, and configuration.
 4. Configure the storage service in `config/environments/*` with `config.active_storage.service = :local`
    that references the services configured in `config/storage_services.yml`.
+5. Optional: Add `gem "mini_magick"` to your Gemfile if you want to use variants.
 
 ## Todos
 
-- 
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