Fix decimal and double #round method to round towards positive for negative numbers, as called for in XPath function.

Author: gkellogg

lib/rdf/model/literal/decimal.rb

@@ -63,9 +63,15 @@ def abs
     ##
     # Returns the number with no fractional part that is closest to the argument. If there are two such numbers, then the one that is closest to positive infinity is returned. An error is raised if arg is not a numeric value.
     #
-    # @return [RDF::Literal::Integer]
+    # @return [RDF::Literal::Decimal]
     def round
-      RDF::Literal::Integer.new(to_d.round)
+      rounded = to_d.round(half: (to_d < 0 ? :down : :up))
+      if rounded == -0.0
+        # to avoid -0.0
+        self.class.new(0.0)
+      else
+        self.class.new(rounded)
+      end
     end
 
     ##

lib/rdf/model/literal/double.rb

@@ -181,11 +181,11 @@ def abs
     end
 
     ##
-    # Returns the integer with no fractional part that is closest to the argument. If there are two such numbers, then the one that is closest to positive infinity is returned. An error is raised if arg is not a numeric value.
+    # Returns the number with no fractional part that is closest to the argument. If there are two such numbers, then the one that is closest to positive infinity is returned. An error is raised if arg is not a numeric value.
     #
-    # @return [RDF::Literal::Integer]
+    # @return [RDF::Literal::Double]
     def round
-      RDF::Literal::Integer.new(to_f.round)
+      self.class.new(to_d.round(half: (to_d < 0 ? :down : :up)))
     end
 
     ##

spec/model_literal_spec.rb

@@ -1044,12 +1044,16 @@ def self.literals(*selector)
         0                  => 0,
         BigDecimal("1.1")  => BigDecimal("1"),
         BigDecimal("-1.1") => BigDecimal("-1"),
+        BigDecimal("0.5")  => BigDecimal("1"),
+        BigDecimal("-0.5") => BigDecimal("0"),
         BigDecimal("1.5")  => BigDecimal("2"),
-        BigDecimal("-1.5") => BigDecimal("-2"),
-        +0.0               => 0,
-        -0.0               => 0,
-        1.5                => 2,
-        -1.5               => -2,
+        BigDecimal("-1.5") => BigDecimal("-1"),
+        +0.0e0             => 0.0e0,
+        -0.0e0             => 0e0,
+        0.5e0              => 1e0,
+        -0.5e0             => -0e0,
+        1.5e0              => 2e0,
+        -1.5e0             => -1e0,
         1.2e0              => 1.0e0,
         -1.2e0             => -1.0e0
       }.each do |value, result|