diff --git a/Rakefile b/Rakefile
index 88f6e80..061329c 100644
--- a/Rakefile
+++ b/Rakefile
@@ -9,3 +9,9 @@ Rake::TestTask.new(:test) do |test|
 end
 
 task :default => :test
+
+desc 'Open an irb session preloaded with the gem library'
+task :console do
+      sh 'irb -rubygems -I lib -r"fluent/load"'
+end
+task :c => :console
diff --git a/test/helper.rb b/test/helper.rb
index 615c410..0b75b4a 100644
--- a/test/helper.rb
+++ b/test/helper.rb
@@ -16,4 +16,12 @@
 require 'fluent/plugin/filter_flowcounter_simple'
 
 class Test::Unit::TestCase
+  def capture_log(log)
+    tmp = log.out
+    log.out = StringIO.new
+    yield
+    return log.out.string
+  ensure
+    log.out = tmp
+  end
 end
diff --git a/test/plugin/test_filter_flowcounter_simple.rb b/test/plugin/test_filter_flowcounter_simple.rb
index df6b4ee..609090f 100644
--- a/test/plugin/test_filter_flowcounter_simple.rb
+++ b/test/plugin/test_filter_flowcounter_simple.rb
@@ -24,9 +24,9 @@ def test_filter
       msgs << {'message'=> 'b' * 100}
     end
     d = create_driver
-    filtered, log = filter(d, msgs)
+    filtered, out = filter(d, msgs)
     assert_equal msgs, filtered
-    assert( log.include?("count:20"), log )
+    assert( out.include?("count:20"), out )
   end
 
   private
@@ -39,20 +39,11 @@ def filter(d,  msgs)
         d.filter(msg, @time)
       }
     }
-    log = capture_log(d.instance.output.log) do
+    out = capture_log(d.instance.output.log) do
       d.instance.flush_emit(0)
     end
     filtered = d.filtered_as_array
     filtered_msgs = filtered.map {|m| m[2] }
-    [filtered_msgs, log]
+    [filtered_msgs, out]
   end
-
-  def capture_log(log)
-    tmp = log.out
-    log.out = StringIO.new
-    yield
-    return log.out.string
-  ensure
-    log.out = tmp
-  end
-end if defined?(Fluent::Test::FilterTestDriver)
+end if defined?(Fluent::Filter)
diff --git a/test/plugin/test_out_flowcounter_simple.rb b/test/plugin/test_out_flowcounter_simple.rb
index 3fff44f..1d01263 100644
--- a/test/plugin/test_out_flowcounter_simple.rb
+++ b/test/plugin/test_out_flowcounter_simple.rb
@@ -66,15 +66,4 @@ def test_comment
     out = capture_log(d1.instance.log) { d1.instance.flush_emit(60) }
     assert( out.include?("comment:foobar"), out )
   end
-
-  private
-
-  def capture_log(log)
-    tmp = log.out
-    log.out = StringIO.new
-    yield
-    return log.out.string
-  ensure
-    log.out = tmp
-  end
 end