* ext/coverage/coverage.c: resurrect r32071 + add GC guard for

rb_coverages. [ruby-core:37352] [Bug #4927]
  [ruby-core:36539] [Feature #4796]

* test/coverage/test_coverage.rb resurrect r32071.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@32404 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/coverage/test_coverage.rb

@@ -15,4 +15,29 @@ class TestCoverage < Test::Unit::TestCase
       assert_kind_of(Array, val)
     end
   end
+
+  def test_restarting_coverage
+    loaded_features = $".dup
+
+    Dir.mktmpdir {|tmp|
+      Dir.chdir(tmp) {
+        File.open("test.rb", "w") do |f|
+          f.puts <<-EOS
+            def coverage_test_method
+              :ok
+            end
+          EOS
+        end
+
+        Coverage.start
+        require tmp + '/test.rb'
+        Coverage.result
+        Coverage.start
+        coverage_test_method
+        assert_equal 1, Coverage.result.size
+      }
+    }
+  ensure
+    $".replace loaded_features
+  end
 end