Fix test code and extension to avoid using gvars and Kernel methods

ext/-test-/ensure_and_callcc/ensure_and_callcc.c

@@ -1,5 +1,7 @@
 #include "ruby.h"
 
+static VALUE rb_mEnsureAndCallcc;
+
 struct require_data {
     VALUE obj;
     VALUE fname;
@@ -16,9 +18,9 @@ call_require(VALUE arg)
 static VALUE
 call_ensure(VALUE _)
 {
-    VALUE v = rb_gv_get("$ensure_called");
+    VALUE v = rb_iv_get(rb_mEnsureAndCallcc, "@ensure_called");
     int called = FIX2INT(v) + 1;
-    rb_gv_set("$ensure_called", INT2FIX(called));
+    rb_iv_set(rb_mEnsureAndCallcc, "@ensure_called", INT2FIX(called));
     return Qnil;
 }
 
@@ -32,8 +34,17 @@ require_with_ensure(VALUE self, VALUE fname)
     return rb_ensure(call_require, (VALUE)&data, call_ensure, Qnil);
 }
 
+static VALUE
+ensure_called(VALUE self)
+{
+    return rb_iv_get(rb_mEnsureAndCallcc, "@ensure_called");
+}
+
 void
 Init_ensure_and_callcc(void)
 {
-    rb_define_method(rb_mKernel, "require_with_ensure", require_with_ensure, 1);
+    rb_mEnsureAndCallcc = rb_define_module("EnsureAndCallcc");
+    rb_iv_set(rb_mEnsureAndCallcc, "@ensure_called", INT2FIX(0));
+    rb_define_singleton_method(rb_mEnsureAndCallcc, "ensure_called", ensure_called, 0);
+    rb_define_singleton_method(rb_mEnsureAndCallcc, "require_with_ensure", require_with_ensure, 1);
 }

test/-ext-/test_ensure_and_callcc.rb

@@ -3,8 +3,6 @@
 require 'test/unit'
 
 class TestEnsureAndCallcc < Test::Unit::TestCase
-  require '-test-/ensure_and_callcc'
-
   def test_bug20655_dir_chdir_using_rb_ensure
     need_continuation
     called = 0
@@ -21,9 +19,11 @@ class TestEnsureAndCallcc < Test::Unit::TestCase
 
   def test_bug20655_extension_using_rb_ensure
     need_continuation
-    $ensure_called = 0
-    require_with_ensure(File.join(__dir__, 'required'))
-    assert_equal(1, $ensure_called, "BUG #20655: ensure called unexpectedly in the required script even without exceptions")
+    require '-test-/ensure_and_callcc'
+    assert_equal(0, EnsureAndCallcc.ensure_called)
+    EnsureAndCallcc.require_with_ensure(File.join(__dir__, 'required'))
+    assert_equal(1, EnsureAndCallcc.ensure_called,
+                 "BUG #20655: ensure called unexpectedly in the required script even without exceptions")
   end
 
   private