Fix #5221: Trying to upload an unsupported url shows ai tags error.

test/test_helpers/autotagger_helper.rb

@@ -0,0 +1,11 @@
+module AutotaggerHelper
+  def mock_autotagger_evaluate(tags, http: Danbooru::Http.any_instance)
+    tags.keys.each { |name| create(:tag, name: name) }
+
+    Danbooru.config.stubs(:autotagger_url).returns("http://localhost:5000")
+    body = [{ filename: "test.jpg", tags: tags }]
+
+    response = HTTP::Response.new(status: 200, body: body.to_json, version: "1.1", request: nil, headers: { "Content-Type": "application/json" })
+    http.stubs(:post).with("http://localhost:5000/evaluate", anything).returns(response)
+  end
+end