Use new Embulk bootstrap mechanism.

Author: hiroyuki-sato

test/helper.rb

@@ -4,14 +4,14 @@
 require 'test/unit'
 require 'test/unit/rr'
 
+# Embulk 0.10.x introduced new bootstrap mechanism.
+# https://github.com/embulk/embulk/blob/641f35fec064cca7b1a7314d634a4b64ef8637f1/embulk-ruby/test/vanilla/run-test.rb#L8-L13
+static_initializer = Java::org.embulk.EmbulkDependencyClassLoader.staticInitializer().useSelfContainedJarFiles()
+static_initializer.java_send :initialize
+
+require 'embulk/java/bootstrap'
 require 'embulk'
-begin
-  # Embulk ~> 0.8.x
-  Embulk.setup
-rescue NotImplementedError, NoMethodError, NameError
-  # Embulk ~> 0.9.x
-  require 'embulk/java/bootstrap'
-end
+
 Embulk.logger = Embulk::Logger.new('/dev/null')
 
 APP_ROOT = File.expand_path('../', __dir__)