1 files changed, 12 insertions, 0 deletions
diff --git a/spec/ruby/core/string/casecmp_spec.rb b/spec/ruby/core/string/casecmp_spec.rb
index c77d97815c..f556c79346 100644
--- a/spec/ruby/core/string/casecmp_spec.rb
+++ b/spec/ruby/core/string/casecmp_spec.rb
@@ -180,5 +180,17 @@ ruby_version_is "2.4" do
         end
       end
     end
+
+    ruby_version_is "2.4" ... "2.5" do
+      it "raises a TypeError if other can't be converted to a string" do
+        lambda { "abc".casecmp?(mock('abc')) }.should raise_error(TypeError)
+      end
+    end
+
+    ruby_version_is "2.5" do
+      it "returns nil if other can't be converted to a string" do
+        "abc".casecmp?(mock('abc')).should be_nil
+      end
+    end
   end
 end