Support for the XPath round() function.

spec/oga/xpath/evaluator/calls/round_spec.rb

@@ -0,0 +1,30 @@
+require 'spec_helper'
+
+describe Oga::XPath::Evaluator do
+  context 'round() function' do
+    before do
+      @document  = parse('<root>10.123</root>')
+      @evaluator = described_class.new(@document)
+    end
+
+    example 'return the rounded value of a literal number' do
+      @evaluator.evaluate('round(10.123)').should == 10.0
+    end
+
+    example 'return the rounded value of a literal string' do
+      @evaluator.evaluate('round("10.123")').should == 10.0
+    end
+
+    example 'return the rounded value of a node set' do
+      @evaluator.evaluate('round(root)').should == 10.0
+    end
+
+    example 'return NaN for empty node sets' do
+      @evaluator.evaluate('round(foo)').should be_nan
+    end
+
+    example 'return NaN for an empty literal string' do
+      @evaluator.evaluate('round("")').should be_nan
+    end
+  end
+end