Basic support for the preceding-sibling xpath axis

spec/oga/xpath/evaluator/axes/preceding_sibling_spec.rb

@@ -0,0 +1,33 @@
+require 'spec_helper'
+
+describe Oga::XPath::Evaluator do
+  context 'preceding-sibling axis' do
+    before do
+      @document = parse(<<-EOF.strip.gsub(/\s+/m, ''))
+<root>
+  <foo>
+  </foo>
+  <bar>
+    <foo></foo>
+    <baz></baz>
+  </bar>
+</root>
+      EOF
+
+      @second_foo = @document.children[0].children[1].children[0]
+      @evaluator  = described_class.new(@document)
+    end
+
+    context 'matching nodes in the current context' do
+      before do
+        @set = @evaluator.evaluate('root/bar/baz/preceding-sibling::foo')
+      end
+
+      it_behaves_like :node_set, :length => 1
+
+      example 'return the second <foo> node' do
+        @set[0].should == @second_foo
+      end
+    end
+  end
+end