Fix WEBrick::TestFileHandler#test_short_filename test not working

The test is currently skipped and can't possibly work on windows at the
moment. It fails because $LOAD_PATH is not set up properly in the forked
CGI process, so `require 'uri'` fails.

This works properly in the test_cgi.rb tests, because it sets up a
:RequestCallback to fix things up. Let's move the setup there into
util.rb, so it can be shared with test_filehandler.rb as well.

tool/test/webrick/test_cgi.rb

@@ -12,30 +12,8 @@ class TestWEBrickCGI < Test::Unit::TestCase
     super
   end
 
-  def start_cgi_server(log_tester=TestWEBrick::DefaultLogTester, &block)
-    config = {
-      :CGIInterpreter => TestWEBrick::RubyBin,
-      :DocumentRoot => File.dirname(__FILE__),
-      :DirectoryIndex => ["webrick.cgi"],
-      :RequestCallback => Proc.new{|req, res|
-        def req.meta_vars
-          meta = super
-          meta["RUBYLIB"] = $:.join(File::PATH_SEPARATOR)
-          meta[RbConfig::CONFIG['LIBPATHENV']] = ENV[RbConfig::CONFIG['LIBPATHENV']] if RbConfig::CONFIG['LIBPATHENV']
-          return meta
-        end
-      },
-    }
-    if RUBY_PLATFORM =~ /mswin|mingw|cygwin|bccwin32/
-      config[:CGIPathEnv] = ENV['PATH'] # runtime dll may not be in system dir.
-    end
-    TestWEBrick.start_httpserver(config, log_tester){|server, addr, port, log|
-      block.call(server, addr, port, log)
-    }
-  end
-
   def test_cgi
-    start_cgi_server{|server, addr, port, log|
+    TestWEBrick.start_cgi_server{|server, addr, port, log|
       http = Net::HTTP.new(addr, port)
       req = Net::HTTP::Get.new("/webrick.cgi")
       http.request(req){|res| assert_equal("/webrick.cgi", res.body, log.call)}
@@ -98,7 +76,7 @@ class TestWEBrickCGI < Test::Unit::TestCase
     log_tester = lambda {|log, access_log|
       assert_match(/BadRequest/, log.join)
     }
-    start_cgi_server(log_tester) {|server, addr, port, log|
+    TestWEBrick.start_cgi_server({}, log_tester) {|server, addr, port, log|
       sock = TCPSocket.new(addr, port)
       begin
         sock << "POST /webrick.cgi HTTP/1.0" << CRLF
@@ -115,7 +93,7 @@ class TestWEBrickCGI < Test::Unit::TestCase
   end
 
   def test_cgi_env
-    start_cgi_server do |server, addr, port, log|
+    TestWEBrick.start_cgi_server do |server, addr, port, log|
       http = Net::HTTP.new(addr, port)
       req = Net::HTTP::Get.new("/webrick.cgi/dumpenv")
       req['proxy'] = 'http://example.com/'
@@ -137,7 +115,7 @@ class TestWEBrickCGI < Test::Unit::TestCase
       assert_equal(1, log.length)
       assert_match(/ERROR bad URI/, log[0])
     }
-    start_cgi_server(log_tester) {|server, addr, port, log|
+    TestWEBrick.start_cgi_server({}, log_tester) {|server, addr, port, log|
       res = TCPSocket.open(addr, port) {|sock|
         sock << "GET /#{CtrlSeq}#{CRLF}#{CRLF}"
         sock.close_write
@@ -155,7 +133,7 @@ class TestWEBrickCGI < Test::Unit::TestCase
       assert_equal(1, log.length)
       assert_match(/ERROR bad header/, log[0])
     }
-    start_cgi_server(log_tester) {|server, addr, port, log|
+    TestWEBrick.start_cgi_server({}, log_tester) {|server, addr, port, log|
       res = TCPSocket.open(addr, port) {|sock|
         sock << "GET / HTTP/1.0#{CRLF}#{CtrlSeq}#{CRLF}#{CRLF}"
         sock.close_write

tool/test/webrick/test_filehandler.rb

@@ -247,22 +247,16 @@ class WEBrick::TestFileHandler < Test::Unit::TestCase
 
   def test_short_filename
     return if File.executable?(__FILE__) # skip on strange file system
-    return if /mswin/ =~ RUBY_PLATFORM && ENV.key?('GITHUB_ACTIONS') # not working from the beginning
 
-    config = {
-      :CGIInterpreter => TestWEBrick::RubyBin,
-      :DocumentRoot => File.dirname(__FILE__),
-      :CGIPathEnv => ENV['PATH'],
-    }
     log_tester = lambda {|log, access_log|
       log = log.reject {|s| /ERROR `.*\' not found\./ =~ s }
       log = log.reject {|s| /WARN  the request refers nondisclosure name/ =~ s }
       assert_equal([], log)
     }
-    TestWEBrick.start_httpserver(config, log_tester) do |server, addr, port, log|
+    TestWEBrick.start_cgi_server({}, log_tester) do |server, addr, port, log|
       http = Net::HTTP.new(addr, port)
       if windows?
-        root = config[:DocumentRoot].tr("/", "\\")
+        root = File.dirname(__FILE__).tr("/", "\\")
         fname = IO.popen(%W[dir /x #{root}\\webrick_long_filename.cgi], encoding: "binary", &:read)
         fname.sub!(/\A.*$^$.*$^$/m, '')
         if fname

tool/test/webrick/utils.rb

@@ -81,4 +81,24 @@ module TestWEBrick
   def start_httpproxy(config={}, log_tester=DefaultLogTester, &block)
     start_server(WEBrick::HTTPProxyServer, config, log_tester, &block)
   end
+
+  def start_cgi_server(config={}, log_tester=TestWEBrick::DefaultLogTester, &block)
+    config = {
+      :CGIInterpreter => TestWEBrick::RubyBin,
+      :DocumentRoot => File.dirname(__FILE__),
+      :DirectoryIndex => ["webrick.cgi"],
+      :RequestCallback => Proc.new{|req, res|
+        def req.meta_vars
+          meta = super
+          meta["RUBYLIB"] = $:.join(File::PATH_SEPARATOR)
+          meta[RbConfig::CONFIG['LIBPATHENV']] = ENV[RbConfig::CONFIG['LIBPATHENV']] if RbConfig::CONFIG['LIBPATHENV']
+          return meta
+        end
+      },
+    }.merge(config)
+    if RUBY_PLATFORM =~ /mswin|mingw|cygwin|bccwin32/
+      config[:CGIPathEnv] = ENV['PATH'] # runtime dll may not be in system dir.
+    end
+    start_server(WEBrick::HTTPServer, config, log_tester, &block)
+  end
 end