Actually upload the files when passed as File or Pathname

This is a follow-up to rails#45606

We were storing the file metadata in Blob and Attachment but we were not
actually uploading the files (into the file system for instance for disk
storage).

It was failing silently so I made it explicit what is accepted and what
is unexpected

activestorage/lib/active_storage/attached/changes/create_one.rb

@@ -30,6 +30,18 @@ def upload
         )
       when Hash
         blob.upload_without_unfurling(attachable.fetch(:io))
+      when File
+        blob.upload_without_unfurling(attachable)
+      when Pathname
+        blob.upload_without_unfurling(attachable.open)
+      when ActiveStorage::Blob
+      when String
+      else
+        raise(
+          ArgumentError,
+          "Could not upload: expected attachable, " \
+            "got #{attachable.inspect}"
+        )
       end
     end
 
@@ -97,7 +109,11 @@ def find_or_build_blob
             service_name: attachment_service_name
           )
         else
-          raise ArgumentError, "Could not find or build blob: expected attachable, got #{attachable.inspect}"
+          raise(
+            ArgumentError,
+            "Could not find or build blob: expected attachable, " \
+              "got #{attachable.inspect}"
+          )
         end
       end
 

activestorage/test/models/attached/one_test.rb

@@ -24,6 +24,11 @@ class ActiveStorage::OneAttachedTest < ActiveSupport::TestCase
     assert_not_nil @user.avatar_blob
   end
 
+  test "uploads the file when passing a File as attachable attribute" do
+    @user = User.create!(name: "Dorian", avatar: file_fixture("image.gif").open)
+    assert_nothing_raised { @user.avatar.download }
+  end
+
   test "creating a record with a Pathname as attachable attribute" do
     @user = User.create!(name: "Dorian", avatar: file_fixture("image.gif"))
 
@@ -32,6 +37,11 @@ class ActiveStorage::OneAttachedTest < ActiveSupport::TestCase
     assert_not_nil @user.avatar_blob
   end
 
+  test "uploads the file when passing a Pathname as attachable attribute" do
+    @user = User.create!(name: "Dorian", avatar: file_fixture("image.gif"))
+    assert_nothing_raised { @user.avatar.download }
+  end
+
   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