posts: normalize Unicode to NFC form in post sources.

Fix strings like "pokémon" (NFD form) and "pokémon" (NFC form) being
considered different strings in sources.

Also add a fix script to fix existing sources. There were only 15 posts
with unnormalized sources.

app/models/post.rb

@@ -1,6 +1,4 @@
 # frozen_string_literal: true
-# normalize unicode in non-web sources
-# normalize percent-encode unicode in source urls
 
 class Post < ApplicationRecord
   class RevertError < StandardError; end
@@ -14,9 +12,9 @@ class Post < ApplicationRecord
 
   deletable
 
+  normalize :source, :normalize_source
   before_validation :merge_old_changes
   before_validation :normalize_tags
-  before_validation :strip_source
   before_validation :parse_pixiv_id
   before_validation :blank_out_nonexistent_parents
   before_validation :remove_parent_loops
@@ -1334,8 +1332,8 @@ class Post < ApplicationRecord
     self
   end
 
-  def strip_source
-    self.source = source.try(:strip)
+  def self.normalize_source(source)
+    source.to_s.strip.unicode_normalize(:nfc)
   end
 
   def mark_as_translated(params)

script/fixes/097_normalize_post_sources.rb

@@ -0,0 +1,14 @@
+#!/usr/bin/env ruby
+
+require_relative "base"
+
+with_confirmation do
+  CurrentUser.scoped(User.system, "127.0.0.1") do
+    Post.where("source ~ '[^[:ascii:]]'").find_each do |post|
+      next if post.source.unicode_normalize(:nfc) == post.source
+
+      post.update!(source: post.source)
+      puts({ id: post.id, old_source: post.source_before_last_save, new_source: post.source })
+    end
+  end
+end

test/unit/post_test.rb

@@ -1340,6 +1340,15 @@ class PostTest < ActiveSupport::TestCase
       end
 
       context "with a source" do
+        context "that contains unicode characters" do
+          should "normalize the source to NFC form" do
+            source1 = "poke\u0301mon" # pokémon (nfd form)
+            source2 = "pok\u00e9mon"  # pokémon (nfc form)
+            @post.update!(source: source1)
+            assert_equal(source2, @post.source)
+          end
+        end
+
         context "that is not from pixiv" do
           should "clear the pixiv id" do
             @post.pixiv_id = 1234

test/unit/upload_service_test.rb

@@ -294,32 +294,4 @@ class UploadServiceTest < ActiveSupport::TestCase
       end
     end
   end
-
-  context "#start!" do
-    subject { UploadService }
-
-    setup do
-      @source = "https://cdn.donmai.us/original/d3/4e/d34e4cf0a437a5d65f8e82b7bcd02606.jpg"
-      CurrentUser.user = travel_to(1.month.ago) do
-        FactoryBot.create(:user)
-      end
-      CurrentUser.ip_addr = "127.0.0.1"
-    end
-
-    teardown do
-      CurrentUser.user = nil
-      CurrentUser.ip_addr = nil
-    end
-
-    context "with a source containing unicode characters" do
-      should "normalize unicode characters in the source field" do
-        source1 = "poke\u0301mon" # pokémon (nfd form)
-        source2 = "pok\u00e9mon"  # pokémon (nfc form)
-        service = subject.new(source: source1, rating: "s", file: upload_file("test/files/test.jpg"))
-
-        assert_nothing_raised { @upload = service.start! }
-        assert_equal(source2, @upload.source)
-      end
-    end
-  end
 end