1 files changed, 19 insertions, 3 deletions
diff --git a/spec/ruby/core/io/ungetbyte_spec.rb b/spec/ruby/core/io/ungetbyte_spec.rb
index c22661582b..b7de1b7a6d 100644
--- a/spec/ruby/core/io/ungetbyte_spec.rb
+++ b/spec/ruby/core/io/ungetbyte_spec.rb
@@ -36,9 +36,25 @@ describe "IO#ungetbyte" do
     @io.getbyte.should == 97
   end
 
-  it "puts back one byte for an Integer argument" do
-    @io.ungetbyte(4095).should be_nil
-    @io.getbyte.should == 255
+  ruby_version_is ''...'2.6' do
+    it "puts back one byte for a Fixnum argument..." do
+      @io.ungetbyte(4095).should be_nil
+      @io.getbyte.should == 255
+    end
+
+    it "... but not for Bignum argument (eh?)" do
+      lambda {
+        @io.ungetbyte(0x4f7574206f6620636861722072616e6765)
+      }.should raise_error(TypeError)
+    end
+  end
+
+  ruby_version_is '2.6' do
+    it "is an RangeError if the integr is not in 8bit" do
+      for i in [4095, 0x4f7574206f6620636861722072616e6765] do
+        lambda { @io.ungetbyte(i) }.should raise_error(RangeError)
+      end
+    end
   end
 
   it "raises an IOError if the IO is closed" do