leakchecker.rb: get rid of uninitialized Tempfile

* test/lib/leakchecker.rb (LeakChecker#find_tempfiles): get rid of
  errors on uninitialized Tempfile, which can be left when
  Dir.tmpdir failed or by Tempfile.allocate.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@57437 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/lib/leakchecker.rb

@@ -114,7 +114,9 @@ class LeakChecker
     if prev_count == count
       [prev_count, []]
     else
-      tempfiles = ObjectSpace.each_object(Tempfile).find_all {|t| t.path }
+      tempfiles = ObjectSpace.each_object(Tempfile).find_all {|t|
+        t.instance_variable_defined?(:@tmpfile) and t.path
+      }
       [count, tempfiles]
     end
   end

test/test_tempfile.rb

@@ -20,6 +20,10 @@ class TestTempfile < Test::Unit::TestCase
     end
   end
 
+  def test_leackchecker
+    assert_instance_of(Tempfile, Tempfile.allocate)
+  end
+
   def test_basic
     t = tempfile("foo")
     path = t.path