numeric.c: fix exception message for nil rounding

* numeric.c (rb_num_get_rounding_option): fix exception message
  for the case of nil rounding mode.

* test_float.rb: add an assertion for the above change.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@57000 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

2 files changed, 7 insertions, 1 deletions

diff --git a/numeric.c b/numeric.c
index 74771cba6f..74ee5d136a 100644
--- a/numeric.c
+++ b/numeric.c
@@ -243,7 +243,10 @@ rb_num_get_rounding_option(VALUE opts)
 	    break;
 	}
       invalid:
-	rb_raise(rb_eArgError, "invalid rounding mode: % "PRIsVALUE, rounding);
+	if (NIL_P(rounding))
+	    rb_raise(rb_eArgError, "invalid rounding mode: nil");
+	else
+	    rb_raise(rb_eArgError, "invalid rounding mode: % "PRIsVALUE, rounding);
     }
   noopt:
     return RUBY_NUM_ROUND_DEFAULT;
diff --git a/test/ruby/test_float.rb b/test/ruby/test_float.rb
index aed387029e..eccc86740a 100644
--- a/test/ruby/test_float.rb
+++ b/test/ruby/test_float.rb
@@ -723,6 +723,9 @@ class TestFloat < Test::Unit::TestCase
   end
 
   def test_round_half_invalid
+    assert_raise_with_message(ArgumentError, /nil/) {
+      1.0.round(half: nil)
+    }
     assert_raise_with_message(ArgumentError, /xxx/) {
       1.0.round(half: "\0xxx")
     }