Remove WikiPage#meta method

this was only ever needed in tests, and having it on the actual
wiki-page model is just incurring technical debt and installing a
permanent footgun. It is removed and replaced with factories.

This also refactors the event spec to be much more declarative for
visibility tests.

app/models/wiki_page.rb

@@ -29,12 +29,6 @@ class WikiPage
 
   alias_method :==, :eql?
 
-  def meta
-    raise 'Metadata only available for valid pages' unless valid?
-
-    @meta ||= WikiPage::Meta.find_or_create(slug, self)
-  end
-
   # Sorts and groups pages by directory.
   #
   # pages - an array of WikiPage objects.
@@ -242,7 +236,6 @@ class WikiPage
     end
 
     save do
-      @meta = nil if title_changed?
       wiki.update_page(
         @page,
         content: content,

spec/factories/events.rb

@@ -27,10 +27,10 @@ FactoryBot.define do
       action { Event::CREATED }
 
       transient do
-        wiki_page { create(:wiki_page, wiki: create(:project_wiki, project: project)) }
+        wiki_page { create(:wiki_page, project: project) }
       end
 
-      target { wiki_page.meta }
+      target { create(:wiki_page_meta, :for_wiki_page, wiki_page: wiki_page) }
     end
   end
 

spec/factories/wiki_pages.rb

@@ -51,7 +51,14 @@ FactoryBot.define do
         wiki_page { create(:wiki_page, project: project) }
       end
 
-      initialize_with { wiki_page.meta }
+      project { @overrides[:wiki_page]&.project || create(:project) }
+      title { wiki_page.title }
+
+      initialize_with do
+        raise 'Metadata only available for valid pages' unless wiki_page.valid?
+
+        WikiPage::Meta.find_or_create(wiki_page.slug, wiki_page)
+      end
     end
   end
 

spec/models/wiki_page_spec.rb

@@ -664,30 +664,6 @@ describe WikiPage do
     end
   end
 
-  describe '#meta' do
-    it 'returns an appropriate metadata object' do
-      wiki_page = create(:wiki_page)
-
-      expect(wiki_page.meta).to have_attributes(
-        valid?: true,
-        canonical_slug: wiki_page.slug,
-        title: wiki_page.title,
-        project: wiki_page.project,
-        slugs: include(have_attributes(slug: wiki_page.slug))
-      )
-    end
-
-    it 'is up-to-date after updates' do
-      wiki_page = create(:wiki_page)
-      old_title = wiki_page.title
-      new_title = FFaker::Lorem.sentence
-
-      expect do
-        wiki_page.update(title: new_title)
-      end.to change { wiki_page.meta.title }.from(old_title).to(new_title)
-    end
-  end
-
   private
 
   def remove_temp_repo(path)