Merge pull request #1808 from robin850/bigdecimal-round

Fix BigDecimal#round behavior with NAN and INFINITY
jruby · Jul 25, 2014 · 7211c60 · 7211c60
2 parents 3ada3d9 + faae599
commit 7211c60
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diff --git a/core/src/main/java/org/jruby/ext/bigdecimal/RubyBigDecimal.java b/core/src/main/java/org/jruby/ext/bigdecimal/RubyBigDecimal.java
@@ -1559,6 +1559,28 @@ public IRubyObject round(IRubyObject[] args) {
     @JRubyMethod(name = "round", optional = 2)
     public IRubyObject round(ThreadContext context, IRubyObject[] args) {
         int scale = args.length > 0 ? num2int(args[0]) : 0;
+
+        // Special treatment for BigDecimal::NAN and BigDecimal::INFINITY
+        //
+        // If round is called without any argument, we should raise a
+        // FloatDomainError. Otherwise, we don't have to call round ;
+        // we can simply return the number itself.
+        if (scale == 0 && (isNaN() || isInfinity())) {
+            StringBuilder message = new StringBuilder("Computation results to ");
+            message.append("'").append(callMethod(context, "to_s")).append("'");
+
+            // To be consistent with MRI's output
+            if (isNaN()) message.append("(Not a Number)");
+
+            throw getRuntime().newFloatDomainError(message.toString());
+        } else {
+            if (isNaN()) {
+                return newNaN(context.runtime);
+            } else if (isInfinity()) {
+                return newInfinity(context.runtime, infinitySign);
+            }
+        }
+
         RoundingMode mode = (args.length > 1) ? javaRoundingModeFromRubyRoundingMode(context.runtime, args[1]) : getRoundingMode(context.runtime);
         // JRUBY-914: Java 1.4 BigDecimal does not allow a negative scale, so we have to simulate it
         RubyBigDecimal bigDecimal = null;

diff --git a/test/externals/ruby1.9/bigdecimal/test_bigdecimal.rb b/test/externals/ruby1.9/bigdecimal/test_bigdecimal.rb
@@ -802,6 +802,18 @@ def test_round
     end
   end
 
+  def test_round_with_nan_and_infinity
+    [BigDecimal::NAN, BigDecimal::INFINITY, -BigDecimal::INFINITY].each do |number|
+      assert_raise(FloatDomainError) { number.round }
+    end
+  end
+
+  def test_round_with_precision_on_nan_and_infinity
+    assert_equal(true, BigDecimal::NAN.round(1).nan?)
+    assert_equal(BigDecimal::INFINITY, BigDecimal::INFINITY.round(1))
+    assert_equal(-BigDecimal::INFINITY, -BigDecimal::INFINITY.round(1))
+  end
+
   def test_truncate
     assert_equal(3, BigDecimal.new("3.14159").truncate)
     assert_equal(8, BigDecimal.new("8.7").truncate)