1 files changed, 13 insertions, 5 deletions
diff --git a/spec/ruby/core/kernel/shared/sprintf_encoding.rb b/spec/ruby/core/kernel/shared/sprintf_encoding.rb
index c3d62bf3bb..5ca66b9083 100644
--- a/spec/ruby/core/kernel/shared/sprintf_encoding.rb
+++ b/spec/ruby/core/kernel/shared/sprintf_encoding.rb
@@ -1,11 +1,19 @@
 describe :kernel_sprintf_encoding, shared: true do
-  def format(*args)
-    @method.call(*args)
+  it "can produce a string with valid encoding" do
+    string = @method.call("good day %{valid}", valid: "e")
+    string.encoding.should == Encoding::UTF_8
+    string.valid_encoding?.should be_true
+  end
+
+  it "can produce a string with invalid encoding" do
+    string = @method.call("good day %{invalid}", invalid: "\x80")
+    string.encoding.should == Encoding::UTF_8
+    string.valid_encoding?.should be_false
   end
 
   it "returns a String in the same encoding as the format String if compatible" do
     string = "%s".force_encoding(Encoding::KOI8_U)
-    result = format(string, "dogs")
+    result = @method.call(string, "dogs")
     result.encoding.should equal(Encoding::KOI8_U)
   end
 
@@ -13,7 +21,7 @@ describe :kernel_sprintf_encoding, shared: true do
     string = "foo %s".force_encoding(Encoding::US_ASCII)
     argument = "b\303\274r".force_encoding(Encoding::UTF_8)
 
-    result = format(string, argument)
+    result = @method.call(string, argument)
     result.encoding.should equal(Encoding::UTF_8)
   end
 
@@ -22,7 +30,7 @@ describe :kernel_sprintf_encoding, shared: true do
     argument = "Ђ".encode('windows-1251')
 
     -> {
-      format(string, argument)
+      @method.call(string, argument)
     }.should raise_error(Encoding::CompatibilityError)
   end
 end