1 files changed, 6 insertions, 0 deletions
diff --git a/spec/ruby/library/stringscanner/exist_spec.rb b/spec/ruby/library/stringscanner/exist_spec.rb
index beafadc07b..ff860a0d3e 100644
--- a/spec/ruby/library/stringscanner/exist_spec.rb
+++ b/spec/ruby/library/stringscanner/exist_spec.rb
@@ -21,4 +21,10 @@ describe "StringScanner#exist?" do
     @s.scan(/This is/)
     @s.exist?(/i/).should == nil
   end
+
+  it "raises TypeError if given a String" do
+    -> {
+      @s.exist?('T')
+    }.should raise_error(TypeError, 'wrong argument type String (expected Regexp)')
+  end
 end