Add basic support for remote attachments with multiple media types (#34996)

spec/lib/activitypub/parser/media_attachment_parser_spec.rb

@@ -0,0 +1,51 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe ActivityPub::Parser::MediaAttachmentParser do
+  subject { described_class.new(json) }
+
+  let(:json) do
+    {
+      '@context': 'https://www.w3.org/ns/activitystreams',
+      type: 'Document',
+      mediaType: 'image/png',
+      url: 'http://example.com/attachment.png',
+    }.deep_stringify_keys
+  end
+
+  it 'correctly parses media attachment' do
+    expect(subject).to have_attributes(
+      remote_url: 'http://example.com/attachment.png',
+      file_content_type: 'image/png'
+    )
+  end
+
+  context 'when the URL is a link with multiple options' do
+    let(:json) do
+      {
+        '@context': 'https://www.w3.org/ns/activitystreams',
+        type: 'Document',
+        url: [
+          {
+            type: 'Link',
+            mediaType: 'image/png',
+            href: 'http://example.com/attachment.png',
+          },
+          {
+            type: 'Link',
+            mediaType: 'image/avif',
+            href: 'http://example.com/attachment.avif',
+          },
+        ],
+      }.deep_stringify_keys
+    end
+
+    it 'returns the first option' do
+      expect(subject).to have_attributes(
+        remote_url: 'http://example.com/attachment.png',
+        file_content_type: 'image/png'
+      )
+    end
+  end
+end