Optimize CSS expressions produced by Nokogiriautocomplete-performance

Nokogiri produces inefficient XPath expressions when given CSS
expressions such as "a.gfm". Luckily these expressions can be optimized
quite easily while still achieving the same results.

In the two cases where this optimization is applied the run time has
been reduced from around 170 ms to around 15 ms.

1 files changed, 13 insertions, 0 deletions

diff --git a/spec/lib/banzai/querying_spec.rb b/spec/lib/banzai/querying_spec.rb
new file mode 100644
index 00000000000..27da2a7439c
--- /dev/null
+++ b/spec/lib/banzai/querying_spec.rb
@@ -0,0 +1,13 @@
+require 'spec_helper'
+
+describe Banzai::Querying do
+  describe '.css' do
+    it 'optimizes queries for elements with classes' do
+      document = double(:document)
+
+      expect(document).to receive(:xpath).with(/^descendant::a/)
+
+      described_class.css(document, 'a.gfm')
+    end
+  end
+end