diff --git a/test/plugin/test_in_dummy.rb b/test/plugin/test_in_dummy.rb
index d9c0db7618..35b9fd12a5 100644
--- a/test/plugin/test_in_dummy.rb
+++ b/test/plugin/test_in_dummy.rb
@@ -107,7 +107,7 @@ def create_driver(conf)
     test "value of auto increment key is not suspended after stop-and-start" do
       assert !File.exist?(File.join(TEST_PLUGIN_STORAGE_PATH, 'json', 'test-01.json'))
 
-      d1 = create_driver(conf1)
+      d1 = Fluent::Test::InputTestDriver.new(Fluent::Plugin::DummyInput).configure(conf1)
       d1.expected_emits_length = 4
       d1.run
 
@@ -119,12 +119,12 @@ def create_driver(conf)
 
       assert !File.exist?(File.join(TEST_PLUGIN_STORAGE_PATH, 'json', 'test-01.json'))
 
-      d2 = create_driver(conf1)
-      d2.expected_emits_length = 4
-      d2.run
+      d2 = Fluent::Test::InputTestDriver.new(Fluent::Plugin::DummyInput).configure(conf1)
 
+      d2.run
+      d2.expected_emits_length = 4
       first_id2 = d2.emits.first[2]['id']
-      assert_equal 0, first_id2
+      assert_equal d1.emits.length, first_id2
 
       assert !File.exist?(File.join(TEST_PLUGIN_STORAGE_PATH, 'json', 'test-01.json'))
     end
@@ -158,10 +158,10 @@ def create_driver(conf)
     test "value of auto increment key is suspended after stop-and-start" do
       assert !File.exist?(File.join(TEST_PLUGIN_STORAGE_PATH, 'json', 'test-02.json'))
 
-      d1 = create_driver(conf2)
+      d1 = Fluent::Test::InputTestDriver.new(Fluent::Plugin::DummyInput).configure(conf2)
 
-      d1.expected_emits_length = 4
       d1.run
+      d1.expected_emits_length = 4
 
       first_id1 = d1.emits.first[2]['id']
       assert_equal 0, first_id1
@@ -171,9 +171,9 @@ def create_driver(conf)
 
       assert File.exist?(File.join(TEST_PLUGIN_STORAGE_PATH, 'json', 'test-02.json'))
 
-      d2 = create_driver(conf2)
-      d2.expected_emits_length = 4
+      d2 = Fluent::Test::InputTestDriver.new(Fluent::Plugin::DummyInput).configure(conf2)
       d2.run
+      d2.expected_emits_length = 4
 
       first_id2 = d2.emits.first[2]['id']
       assert_equal last_id1 + 1, first_id2