1 files changed, 18 insertions, 16 deletions
diff --git a/tests/test_json_generate.rb b/tests/test_json_generate.rb
index b363de1..3a1ddc6 100755
--- a/tests/test_json_generate.rb
+++ b/tests/test_json_generate.rb
@@ -227,23 +227,25 @@ EOT
     GC.stress = stress
   end if GC.respond_to?(:stress=)
 
-  def test_broken_bignum # [ruby-core:38867]
-    pid = fork do
-      Bignum.class_eval do
-        def to_s
+  if defined?(JSON::Ext::Generator)
+    def test_broken_bignum # [ruby-core:38867]
+      pid = fork do
+        Bignum.class_eval do
+          def to_s
+          end
+        end
+        begin
+          JSON::Ext::Generator::State.new.generate(1<<64)
+          exit 1
+        rescue TypeError
+          exit 0
         end
       end
-      begin
-        JSON::Ext::Generator::State.new.generate(1<<64)
-        exit 1
-      rescue TypeError
-        exit 0
-      end
+      _, status = Process.waitpid2(pid)
+      assert status.success?
+    rescue NotImplementedError
+      # forking to avoid modifying core class of a parent process and
+      # introducing race conditions of tests are run in parallel
     end
-    _, status = Process.waitpid2(pid)
-    assert status.success?
-  rescue NotImplementedError
-    # forking to avoid modifying core class of a parent process and
-    # introducing race conditions of tests are run in parallel
-  end if defined?(JSON::Ext)
+  end
 end