diff --git a/test/test_cgi_server.rb b/test/test_cgi_server.rb
new file mode 100644
index 0000000..2cbd37f
--- /dev/null
+++ b/test/test_cgi_server.rb
@@ -0,0 +1,140 @@
+# coding: utf-8
+# frozen_string_literal: false
+
+require 'test/unit'
+require 'webrick'
+require_relative 'webrick_testing'
+require 'tempfile'
+require "xmlrpc/server"
+require 'xmlrpc/client'
+
+class TestCGIServer < Test::Unit::TestCase
+  include WEBrick_Testing
+
+  def setup_http_server_option(use_ssl)
+    option = {
+      :BindAddress => "localhost",
+      :Port => 0,
+      :SSLEnable => use_ssl,
+    }
+    if use_ssl
+      require 'webrick/https'
+      option.update(
+        :SSLVerifyClient => ::OpenSSL::SSL::VERIFY_NONE,
+        :SSLCertName => []
+      )
+    end
+
+    option
+  end
+
+  def test_client_server
+    omit("The CGI file does not work on Windows") if Gem.win_platform?
+
+    Tempfile.create("cgi-bin") do |tempfile|
+      tempfile.write(cgi_bin_script)
+      tempfile.close
+      File.chmod(0755, tempfile.path)
+
+      # NOTE: I don't enable SSL testing as this hangs
+      use_ssl = false
+      option = setup_http_server_option(use_ssl)
+      with_server(option, WEBrick::HTTPServlet::CGIHandler, tempfile.path) do |addr|
+        @s = XMLRPC::Client.new3(:host => addr.ip_address, :port => addr.ip_port, :use_ssl => use_ssl)
+        @s.user = 'admin'
+        @s.password = 'admin'
+        silent do
+          do_test
+        end
+        @s.http.finish
+        @s = XMLRPC::Client.new3(:host => addr.ip_address, :port => addr.ip_port, :use_ssl => use_ssl)
+        @s.user = '01234567890123456789012345678901234567890123456789012345678901234567890123456789'
+        @s.password = 'guest'
+        silent do
+          do_test
+        end
+        @s.http.finish
+      end
+    end
+  end
+
+  def silent
+    begin
+      back, $VERBOSE = $VERBOSE, nil
+      yield
+    ensure
+      $VERBOSE = back
+    end
+  end
+
+  def do_test
+    # simple call
+    assert_equal(9, @s.call('test.add', 4, 5))
+
+    # fault exception
+    assert_raise(XMLRPC::FaultException) { @s.call('test.div', 1, 0) }
+
+    # fault exception via call2
+    ok, param = @s.call2('test.div', 1, 0)
+    assert_equal(false, ok)
+    assert_instance_of(XMLRPC::FaultException, param)
+    assert_equal(1, param.faultCode)
+    assert_equal('division by zero', param.faultString)
+
+    # call2 without fault exception
+    ok, param = @s.call2('test.div', 10, 5)
+    assert_equal(true, ok)
+    assert_equal(param, 2)
+
+    # introspection
+    assert_equal(["test.add", "test.div", "system.listMethods", "system.methodSignature", "system.methodHelp"],
+                 @s.call("system.listMethods"))
+
+    # default handler (missing handler)
+    ok, param = @s.call2('test.nonexisting')
+    assert_equal(false, ok)
+    assert_equal(-99, param.faultCode)
+
+    # default handler (wrong number of arguments)
+    ok, param = @s.call2('test.add', 1, 2, 3)
+    assert_equal(false, ok)
+    assert_equal(-99, param.faultCode)
+
+    # multibyte characters
+    assert_equal("あいうえおかきくけこ", @s.call('test.add', "あいうえお", "かきくけこ"))
+  end
+
+  def cgi_bin_script
+    <<~RUBY
+      #!#{Gem.ruby}
+      # frozen_string_literal: true
+
+      $LOAD_PATH << #{File.expand_path("../lib", __dir__).inspect}
+
+      require "xmlrpc/server"
+
+      s = XMLRPC::CGIServer.new
+
+      s.add_handler("test.add") do |a, b|
+        a + b
+      end
+
+      s.add_handler("test.div") do |a, b|
+        if b == 0
+          raise XMLRPC::FaultException.new(1, "division by zero")
+        else
+          a / b
+        end
+      end
+
+      s.set_default_handler do |name, *args|
+        raise XMLRPC::FaultException.new(-99, "Method \#{name} missing" +
+              " or wrong number of parameters!")
+      end
+
+      s.add_introspection
+
+      s.serve
+    RUBY
+  end
+end
diff --git a/test/test_webrick_server.rb b/test/test_webrick_server.rb
index 98a300b..65aa838 100644
--- a/test/test_webrick_server.rb
+++ b/test/test_webrick_server.rb
@@ -24,11 +24,11 @@ class << s; self end.send(:define_method, :service) {|req, res|
       super(req, res)
     }
 
-    s.add_handler("test.add") do |a,b|
+    s.add_handler("test.add") do |a, b|
       a + b
     end
 
-    s.add_handler("test.div") do |a,b|
+    s.add_handler("test.div") do |a, b|
       if b == 0
         raise XMLRPC::FaultException.new(1, "division by zero")
       else
@@ -65,24 +65,23 @@ def setup_http_server_option(use_ssl)
 
   def test_client_server
     # NOTE: I don't enable SSL testing as this hangs
-    [false].each do |use_ssl|
-      option = setup_http_server_option(use_ssl)
-      with_server(option, method(:create_servlet)) {|addr|
-        @s = XMLRPC::Client.new3(:host => addr.ip_address, :port => addr.ip_port, :use_ssl => use_ssl)
-        @s.user = 'admin'
-        @s.password = 'admin'
-        silent do
-          do_test
-        end
-        @s.http.finish
-        @s = XMLRPC::Client.new3(:host => addr.ip_address, :port => addr.ip_port, :use_ssl => use_ssl)
-        @s.user = '01234567890123456789012345678901234567890123456789012345678901234567890123456789'
-        @s.password = 'guest'
-        silent do
-          do_test
-        end
-        @s.http.finish
-      }
+    use_ssl = false
+    option = setup_http_server_option(use_ssl)
+    with_server(option, method(:create_servlet)) do |addr|
+      @s = XMLRPC::Client.new3(:host => addr.ip_address, :port => addr.ip_port, :use_ssl => use_ssl)
+      @s.user = 'admin'
+      @s.password = 'admin'
+      silent do
+        do_test
+      end
+      @s.http.finish
+      @s = XMLRPC::Client.new3(:host => addr.ip_address, :port => addr.ip_port, :use_ssl => use_ssl)
+      @s.user = '01234567890123456789012345678901234567890123456789012345678901234567890123456789'
+      @s.password = 'guest'
+      silent do
+        do_test
+      end
+      @s.http.finish
     end
   end
 
@@ -97,37 +96,38 @@ def silent
 
   def do_test
     # simple call
-    assert_equal 9, @s.call('test.add', 4, 5)
+    assert_equal(9, @s.call('test.add', 4, 5))
 
     # fault exception
     assert_raise(XMLRPC::FaultException) { @s.call('test.div', 1, 0) }
 
     # fault exception via call2
     ok, param = @s.call2('test.div', 1, 0)
-    assert_equal false, ok
-    assert_instance_of XMLRPC::FaultException, param
-    assert_equal 1, param.faultCode
-    assert_equal 'division by zero', param.faultString
+    assert_equal(false, ok)
+    assert_instance_of(XMLRPC::FaultException, param)
+    assert_equal(1, param.faultCode)
+    assert_equal('division by zero', param.faultString)
 
     # call2 without fault exception
     ok, param = @s.call2('test.div', 10, 5)
-    assert_equal true, ok
-    assert_equal param, 2
+    assert_equal(true, ok)
+    assert_equal(param, 2)
 
     # introspection
-    assert_equal ["test.add", "test.div", "system.listMethods", "system.methodSignature", "system.methodHelp"], @s.call("system.listMethods")
+    assert_equal(["test.add", "test.div", "system.listMethods", "system.methodSignature", "system.methodHelp"],
+                 @s.call("system.listMethods"))
 
     # default handler (missing handler)
     ok, param = @s.call2('test.nonexisting')
-    assert_equal false, ok
+    assert_equal(false, ok)
     assert_equal(-99, param.faultCode)
 
     # default handler (wrong number of arguments)
     ok, param = @s.call2('test.add', 1, 2, 3)
-    assert_equal false, ok
+    assert_equal(false, ok)
     assert_equal(-99, param.faultCode)
 
     # multibyte characters
-    assert_equal "あいうえおかきくけこ", @s.call('test.add', "あいうえお", "かきくけこ")
+    assert_equal("あいうえおかきくけこ", @s.call('test.add', "あいうえお", "かきくけこ"))
   end
 end
diff --git a/test/webrick_testing.rb b/test/webrick_testing.rb
index 2d6d198..48ce4a5 100644
--- a/test/webrick_testing.rb
+++ b/test/webrick_testing.rb
@@ -35,12 +35,12 @@ def start_server(logger, config={})
     addr
   end
 
-  def with_server(config, servlet)
+  def with_server(config, servlet, *args)
     log = []
     logger = WEBrick::Log.new(log, WEBrick::BasicLog::WARN)
     addr = start_server(logger, config) {|w|
       servlet = servlet.call(w) if servlet.respond_to? :call
-      w.mount('/RPC2', servlet)
+      w.mount('/RPC2', servlet, *args)
     }
 
     begin