diff --git a/.document b/.document
new file mode 100644
index 0000000..1d07bdf
--- /dev/null
+++ b/.document
@@ -0,0 +1,5 @@
+BSDL
+COPYING
+README.md
+docs/
+lib/
diff --git a/.github/workflows/gh-pages.yml b/.github/workflows/gh-pages.yml
index f0e6b5d..585eb8a 100644
--- a/.github/workflows/gh-pages.yml
+++ b/.github/workflows/gh-pages.yml
@@ -19,20 +19,20 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v5
       - name: Setup Ruby
-        uses: ruby/setup-ruby@250fcd6a742febb1123a77a841497ccaa8b9e939 # v1.152.0
+        uses: ruby/setup-ruby@32110d4e311bd8996b2a82bf2a43b714ccc91777 # v1.221.0
         with:
-          ruby-version: '3.3'
+          ruby-version: '3.4'
           bundler-cache: true
       - name: Setup Pages
         id: pages
         uses: actions/configure-pages@v5
       - name: Build with RDoc
         # Outputs to the './_site' directory by default
-        run: bundle exec rake rdoc
+        run: rake rdoc
       - name: Upload artifact
-        uses: actions/upload-pages-artifact@v3
+        uses: actions/upload-pages-artifact@v4
 
   deploy:
     environment:
diff --git a/.github/workflows/push_gem.yml b/.github/workflows/push_gem.yml
index e15d54b..c6b1e47 100644
--- a/.github/workflows/push_gem.yml
+++ b/.github/workflows/push_gem.yml
@@ -23,11 +23,11 @@ jobs:
 
     steps:
       - name: Harden Runner
-        uses: step-security/harden-runner@91182cccc01eb5e619899d80e4e971d6181294a7 # v2.10.1
+        uses: step-security/harden-runner@f4a75cfd619ee5ce8d5b864b0d183aff3c69b55a # v2.13.1
         with:
           egress-policy: audit
 
-      - uses: actions/checkout@0ad4b8fadaa221de15dcec353f45205ec38ea70b # v4.1.4
+      - uses: actions/checkout@ff7abcd0c3c05ccf6adc123a8cd1fd4fb30fb493 # v4.1.4
 
       - name: Set up Ruby
         uses: ruby/setup-ruby@a6e6f86333f0a2523ece813039b8b4be04560854 # v1.190.0
@@ -36,11 +36,11 @@ jobs:
           ruby-version: ruby
 
       - name: Publish to RubyGems
-        uses: rubygems/release-gem@612653d273a73bdae1df8453e090060bb4db5f31 # v1
+        uses: rubygems/release-gem@a25424ba2ba8b387abc8ef40807c2c85b96cbe32 # v1.1.1
 
       - name: Create GitHub release
         run: |
           tag_name="$(git describe --tags --abbrev=0)"
           gh release create "${tag_name}" --verify-tag --generate-notes
         env:
-          GITHUB_TOKEN: ${{ secrets.MATZBOT_GITHUB_WORKFLOW_TOKEN }}
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index ee9b2a5..ba860e8 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -20,7 +20,7 @@ jobs:
             os: macos-latest
     runs-on: ${{ matrix.os }}
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v5
     - name: Set up Ruby
       uses: ruby/setup-ruby@v1
       with:
diff --git a/.rdoc_options b/.rdoc_options
new file mode 100644
index 0000000..cd5e496
--- /dev/null
+++ b/.rdoc_options
@@ -0,0 +1,5 @@
+main_page: README.md
+op_dir: _site
+warn_missing_rdoc_ref: true
+title: URI Documentation
+visibility: :private
diff --git a/Gemfile b/Gemfile
index ba909e8..6669eae 100644
--- a/Gemfile
+++ b/Gemfile
@@ -6,5 +6,5 @@ group :development do
   gem "bundler"
   gem "rake"
   gem "test-unit"
-  gem "test-unit-ruby-core"
+  gem "test-unit-ruby-core", ">= 1.0.7"
 end
diff --git a/README.md b/README.md
index 3775f3b..5c7c0dd 100644
--- a/README.md
+++ b/README.md
@@ -3,7 +3,7 @@
 [![CI](https://github.com/ruby/uri/actions/workflows/test.yml/badge.svg)](https://github.com/ruby/uri/actions/workflows/test.yml)
 [![Yard Docs](https://img.shields.io/badge/docs-exist-blue.svg)](https://ruby.github.io/uri/)
 
-URI is a module providing classes to handle Uniform Resource Identifiers [RFC2396](http://tools.ietf.org/html/rfc2396).
+URI is a module providing classes to handle Uniform Resource Identifiers [RFC3986](http://tools.ietf.org/html/rfc3986).
 
 ## Features
 
diff --git a/Rakefile b/Rakefile
index 19de93e..3935fdf 100644
--- a/Rakefile
+++ b/Rakefile
@@ -11,7 +11,7 @@ require "rdoc/task"
 RDoc::Task.new do |doc|
   doc.main   = "README.md"
   doc.title  = "URI - handle Uniform Resource Identifiers"
-  doc.rdoc_files = FileList.new %w[lib README.md LICENSE.txt]
+  doc.rdoc_files = FileList.new %w[lib README.md BSDL COPYING]
   doc.rdoc_dir = "_site" # for github pages
 end
 
diff --git a/docs/kernel.rb b/docs/kernel.rb
new file mode 100644
index 0000000..68ed335
--- /dev/null
+++ b/docs/kernel.rb
@@ -0,0 +1,2 @@
+# :stopdoc:
+module Kernel end
diff --git a/lib/uri/common.rb b/lib/uri/common.rb
index cf93fb1..baa0fd2 100644
--- a/lib/uri/common.rb
+++ b/lib/uri/common.rb
@@ -13,15 +13,19 @@
 require_relative "rfc3986_parser"
 
 module URI
+  # The default parser instance for RFC 2396.
   RFC2396_PARSER = RFC2396_Parser.new
   Ractor.make_shareable(RFC2396_PARSER) if defined?(Ractor)
 
+  # The default parser instance for RFC 3986.
   RFC3986_PARSER = RFC3986_Parser.new
   Ractor.make_shareable(RFC3986_PARSER) if defined?(Ractor)
 
+  # The default parser instance.
   DEFAULT_PARSER = RFC3986_PARSER
   Ractor.make_shareable(DEFAULT_PARSER) if defined?(Ractor)
 
+  # Set the default parser instance.
   def self.parser=(parser = RFC3986_PARSER)
     remove_const(:Parser) if defined?(::URI::Parser)
     const_set("Parser", parser.class)
@@ -31,23 +35,24 @@ def self.parser=(parser = RFC3986_PARSER)
     if Parser == RFC2396_Parser
       const_set("REGEXP", URI::RFC2396_REGEXP)
       const_set("PATTERN", URI::RFC2396_REGEXP::PATTERN)
-      Parser.new.pattern.each_pair do |sym, str|
-        unless REGEXP::PATTERN.const_defined?(sym)
-          REGEXP::PATTERN.const_set(sym, str)
-        end
-      end
     end
 
     Parser.new.regexp.each_pair do |sym, str|
-      remove_const(sym) if const_defined?(sym)
+      remove_const(sym) if const_defined?(sym, false)
       const_set(sym, str)
     end
   end
   self.parser = RFC3986_PARSER
 
-  def self.const_missing(const)
-    if value = RFC2396_PARSER.regexp[const]
-      warn "URI::#{const} is obsolete. Use RFC2396_PARSER.regexp[#{const.inspect}] explicitly.", uplevel: 1 if $VERBOSE
+  def self.const_missing(const) # :nodoc:
+    if const == :REGEXP
+      warn "URI::REGEXP is obsolete. Use URI::RFC2396_REGEXP explicitly.", uplevel: 1 if $VERBOSE
+      URI::RFC2396_REGEXP
+    elsif value = RFC2396_PARSER.regexp[const]
+      warn "URI::#{const} is obsolete. Use URI::RFC2396_PARSER.regexp[#{const.inspect}] explicitly.", uplevel: 1 if $VERBOSE
+      value
+    elsif value = RFC2396_Parser.const_get(const)
+      warn "URI::#{const} is obsolete. Use URI::RFC2396_Parser::#{const} explicitly.", uplevel: 1 if $VERBOSE
       value
     else
       super
@@ -86,7 +91,41 @@ def make_components_hash(klass, array_hash)
     module_function :make_components_hash
   end
 
-  module Schemes
+  module Schemes # :nodoc:
+    class << self
+      ReservedChars = ".+-"
+      EscapedChars = "\u01C0\u01C1\u01C2"
+      # Use Lo category chars as escaped chars for TruffleRuby, which
+      # does not allow Symbol categories as identifiers.
+
+      def escape(name)
+        unless name and name.ascii_only?
+          return nil
+        end
+        name.upcase.tr(ReservedChars, EscapedChars)
+      end
+
+      def unescape(name)
+        name.tr(EscapedChars, ReservedChars).encode(Encoding::US_ASCII).upcase
+      end
+
+      def find(name)
+        const_get(name, false) if name and const_defined?(name, false)
+      end
+
+      def register(name, klass)
+        unless scheme = escape(name)
+          raise ArgumentError, "invalid character as scheme - #{name}"
+        end
+        const_set(scheme, klass)
+      end
+
+      def list
+        constants.map { |name|
+          [unescape(name.to_s), const_get(name)]
+        }.to_h
+      end
+    end
   end
   private_constant :Schemes
 
@@ -99,7 +138,7 @@ module Schemes
   # Note that after calling String#upcase on +scheme+, it must be a valid
   # constant name.
   def self.register_scheme(scheme, klass)
-    Schemes.const_set(scheme.to_s.upcase, klass)
+    Schemes.register(scheme, klass)
   end
 
   # Returns a hash of the defined schemes:
@@ -117,14 +156,14 @@ def self.register_scheme(scheme, klass)
   #
   # Related: URI.register_scheme.
   def self.scheme_list
-    Schemes.constants.map { |name|
-      [name.to_s.upcase, Schemes.const_get(name)]
-    }.to_h
+    Schemes.list
   end
 
+  # :stopdoc:
   INITIAL_SCHEMES = scheme_list
   private_constant :INITIAL_SCHEMES
   Ractor.make_shareable(INITIAL_SCHEMES) if defined?(Ractor)
+  # :startdoc:
 
   # Returns a new object constructed from the given +scheme+, +arguments+,
   # and +default+:
@@ -143,12 +182,10 @@ def self.scheme_list
   #   # => #<URI::HTTP foo://john.doe@www.example.com:123/forum/questions/?tag=networking&order=newest#top>
   #
   def self.for(scheme, *arguments, default: Generic)
-    const_name = scheme.to_s.upcase
+    const_name = Schemes.escape(scheme)
 
     uri_class = INITIAL_SCHEMES[const_name]
-    uri_class ||= if /\A[A-Z]\w*\z/.match?(const_name) && Schemes.const_defined?(const_name, false)
-      Schemes.const_get(const_name, false)
-    end
+    uri_class ||= Schemes.find(const_name)
     uri_class ||= default
 
     return uri_class.new(scheme, *arguments)
@@ -304,7 +341,7 @@ def self.regexp(schemes = nil)# :nodoc:
   256.times do |i|
     TBLENCWWWCOMP_[-i.chr] = -('%%%02X' % i)
   end
-  TBLENCURICOMP_ = TBLENCWWWCOMP_.dup.freeze
+  TBLENCURICOMP_ = TBLENCWWWCOMP_.dup.freeze # :nodoc:
   TBLENCWWWCOMP_[' '] = '+'
   TBLENCWWWCOMP_.freeze
   TBLDECWWWCOMP_ = {} # :nodoc:
@@ -402,6 +439,8 @@ def self.decode_uri_component(str, enc=Encoding::UTF_8)
     _decode_uri_component(/%\h\h/, str, enc)
   end
 
+  # Returns a string derived from the given string +str+ with
+  # URI-encoded characters matching +regexp+ according to +table+.
   def self._encode_uri_component(regexp, table, str, enc)
     str = str.to_s.dup
     if str.encoding != Encoding::ASCII_8BIT
@@ -416,6 +455,8 @@ def self._encode_uri_component(regexp, table, str, enc)
   end
   private_class_method :_encode_uri_component
 
+  # Returns a string decoding characters matching +regexp+ from the
+  # given \URL-encoded string +str+.
   def self._decode_uri_component(regexp, str, enc)
     raise ArgumentError, "invalid %-encoding (#{str})" if /%(?!\h\h)/.match?(str)
     str.b.gsub(regexp, TBLDECWWWCOMP_).force_encoding(enc)
@@ -854,6 +895,7 @@ module Kernel
   # Returns a \URI object derived from the given +uri+,
   # which may be a \URI string or an existing \URI object:
   #
+  #   require 'uri'
   #   # Returns a new URI.
   #   uri = URI('http://github.com/ruby/ruby')
   #   # => #<URI::HTTP http://github.com/ruby/ruby>
@@ -861,6 +903,8 @@ module Kernel
   #   URI(uri)
   #   # => #<URI::HTTP http://github.com/ruby/ruby>
   #
+  # You must require 'uri' to use this method.
+  #
   def URI(uri)
     if uri.is_a?(URI::Generic)
       uri
diff --git a/lib/uri/file.rb b/lib/uri/file.rb
index 940d361..47b5aef 100644
--- a/lib/uri/file.rb
+++ b/lib/uri/file.rb
@@ -47,7 +47,7 @@ class File < Generic
     #       :path => '/ruby/src'})
     #     uri2.to_s  # => "file://host.example.com/ruby/src"
     #
-    #     uri3 = URI::File.build({:path => URI::escape('/path/my file.txt')})
+    #     uri3 = URI::File.build({:path => URI::RFC2396_PARSER.escape('/path/my file.txt')})
     #     uri3.to_s  # => "file:///path/my%20file.txt"
     #
     def self.build(args)
diff --git a/lib/uri/generic.rb b/lib/uri/generic.rb
index d4bfa3b..d811c5b 100644
--- a/lib/uri/generic.rb
+++ b/lib/uri/generic.rb
@@ -73,7 +73,7 @@ def self.use_registry # :nodoc:
     #
     # At first, tries to create a new URI::Generic instance using
     # URI::Generic::build. But, if exception URI::InvalidComponentError is raised,
-    # then it does URI::Escape.escape all URI components and tries again.
+    # then it does URI::RFC2396_PARSER.escape all URI components and tries again.
     #
     def self.build2(args)
       begin
@@ -126,9 +126,9 @@ def self.build(args)
           end
         end
       else
-        component = self.class.component rescue ::URI::Generic::COMPONENT
+        component = self.component rescue ::URI::Generic::COMPONENT
         raise ArgumentError,
-        "expected Array of or Hash of components of #{self.class} (#{component.join(', ')})"
+              "expected Array of or Hash of components of #{self} (#{component.join(', ')})"
       end
 
       tmp << nil
@@ -284,7 +284,7 @@ def registry # :nodoc:
 
     # Returns the parser to be used.
     #
-    # Unless a URI::Parser is defined, DEFAULT_PARSER is used.
+    # Unless the +parser+ is defined, DEFAULT_PARSER is used.
     #
     def parser
       if !defined?(@parser) || !@parser
@@ -315,7 +315,7 @@ def component
     end
 
     #
-    # Checks the scheme +v+ component against the URI::Parser Regexp for :SCHEME.
+    # Checks the scheme +v+ component against the +parser+ Regexp for :SCHEME.
     #
     def check_scheme(v)
       if v && parser.regexp[:SCHEME] !~ v
@@ -385,7 +385,7 @@ def check_userinfo(user, password = nil)
 
     #
     # Checks the user +v+ component for RFC2396 compliance
-    # and against the URI::Parser Regexp for :USERINFO.
+    # and against the +parser+ Regexp for :USERINFO.
     #
     # Can not have a registry or opaque component defined,
     # with a user component defined.
@@ -409,7 +409,7 @@ def check_user(v)
 
     #
     # Checks the password +v+ component for RFC2396 compliance
-    # and against the URI::Parser Regexp for :USERINFO.
+    # and against the +parser+ Regexp for :USERINFO.
     #
     # Can not have a registry or opaque component defined,
     # with a user component defined.
@@ -586,7 +586,7 @@ def decoded_password
 
     #
     # Checks the host +v+ component for RFC2396 compliance
-    # and against the URI::Parser Regexp for :HOST.
+    # and against the +parser+ Regexp for :HOST.
     #
     # Can not have a registry or opaque component defined,
     # with a host component defined.
@@ -675,7 +675,7 @@ def hostname=(v)
 
     #
     # Checks the port +v+ component for RFC2396 compliance
-    # and against the URI::Parser Regexp for :PORT.
+    # and against the +parser+ Regexp for :PORT.
     #
     # Can not have a registry or opaque component defined,
     # with a port component defined.
@@ -737,18 +737,18 @@ def check_registry(v) # :nodoc:
     end
     private :check_registry
 
-    def set_registry(v) #:nodoc:
+    def set_registry(v) # :nodoc:
       raise InvalidURIError, "cannot set registry"
     end
     protected :set_registry
 
-    def registry=(v)
+    def registry=(v) # :nodoc:
       raise InvalidURIError, "cannot set registry"
     end
 
     #
     # Checks the path +v+ component for RFC2396 compliance
-    # and against the URI::Parser Regexp
+    # and against the +parser+ Regexp
     # for :ABS_PATH and :REL_PATH.
     #
     # Can not have a opaque component defined,
@@ -853,7 +853,7 @@ def query=(v)
 
     #
     # Checks the opaque +v+ component for RFC2396 compliance and
-    # against the URI::Parser Regexp for :OPAQUE.
+    # against the +parser+ Regexp for :OPAQUE.
     #
     # Can not have a host, port, user, or path component defined,
     # with an opaque component defined.
@@ -905,7 +905,7 @@ def opaque=(v)
     end
 
     #
-    # Checks the fragment +v+ component against the URI::Parser Regexp for :FRAGMENT.
+    # Checks the fragment +v+ component against the +parser+ Regexp for :FRAGMENT.
     #
     #
     # == Args
@@ -1133,17 +1133,16 @@ def merge(oth)
       base.fragment=(nil)
 
       # RFC2396, Section 5.2, 4)
-      if !authority
-        base.set_path(merge_path(base.path, rel.path)) if base.path && rel.path
-      else
-        # RFC2396, Section 5.2, 4)
-        base.set_path(rel.path) if rel.path
+      if authority
+        base.set_userinfo(rel.userinfo)
+        base.set_host(rel.host)
+        base.set_port(rel.port || base.default_port)
+        base.set_path(rel.path)
+      elsif base.path && rel.path
+        base.set_path(merge_path(base.path, rel.path))
       end
 
       # RFC2396, Section 5.2, 7)
-      base.set_userinfo(rel.userinfo) if rel.userinfo
-      base.set_host(rel.host)         if rel.host
-      base.set_port(rel.port)         if rel.port
       base.query = rel.query       if rel.query
       base.fragment=(rel.fragment) if rel.fragment
 
@@ -1392,10 +1391,12 @@ def ==(oth)
       end
     end
 
+    # Returns the hash value.
     def hash
       self.component_ary.hash
     end
 
+    # Compares with _oth_ for Hash.
     def eql?(oth)
       self.class == oth.class &&
       parser == oth.parser &&
@@ -1438,7 +1439,7 @@ def select(*components)
       end
     end
 
-    def inspect
+    def inspect # :nodoc:
       "#<#{self.class} #{self}>"
     end
 
diff --git a/lib/uri/http.rb b/lib/uri/http.rb
index 900b132..3c41cd4 100644
--- a/lib/uri/http.rb
+++ b/lib/uri/http.rb
@@ -61,6 +61,18 @@ def self.build(args)
       super(tmp)
     end
 
+    # Do not allow empty host names, as they are not allowed by RFC 3986.
+    def check_host(v)
+      ret = super
+
+      if ret && v.empty?
+        raise InvalidComponentError,
+          "bad component(expected host component): #{v}"
+      end
+
+      ret
+    end
+
     #
     # == Description
     #
diff --git a/lib/uri/mailto.rb b/lib/uri/mailto.rb
index cb8024f..f747b79 100644
--- a/lib/uri/mailto.rb
+++ b/lib/uri/mailto.rb
@@ -52,7 +52,11 @@ class MailTo < Generic
     HEADER_REGEXP  = /\A(?<hfield>(?:%\h\h|[!$'-.0-;@-Z_a-z~])*=(?:%\h\h|[!$'-.0-;@-Z_a-z~])*)(?:&\g<hfield>)*\z/
     # practical regexp for email address
     # https://html.spec.whatwg.org/multipage/input.html#valid-e-mail-address
-    EMAIL_REGEXP = /\A[a-zA-Z0-9.!\#$%&'*+\/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*\z/
+    EMAIL_REGEXP = %r[\A#{
+      atext = %q[(?:[a-zA-Z0-9!\#$%&'*+\/=?^_`{|}~-]+)]
+    }(?:\.#{atext})*@#{
+      label = %q[(?:[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)]
+    }(?:\.#{label})*\z]
     # :startdoc:
 
     #
diff --git a/lib/uri/rfc2396_parser.rb b/lib/uri/rfc2396_parser.rb
index a56ca34..cefd126 100644
--- a/lib/uri/rfc2396_parser.rb
+++ b/lib/uri/rfc2396_parser.rb
@@ -67,7 +67,7 @@ class RFC2396_Parser
     #
     # == Synopsis
     #
-    #   URI::Parser.new([opts])
+    #   URI::RFC2396_Parser.new([opts])
     #
     # == Args
     #
@@ -86,7 +86,7 @@ class RFC2396_Parser
     #
     # == Examples
     #
-    #   p = URI::Parser.new(:ESCAPED => "(?:%[a-fA-F0-9]{2}|%u[a-fA-F0-9]{4})")
+    #   p = URI::RFC2396_Parser.new(:ESCAPED => "(?:%[a-fA-F0-9]{2}|%u[a-fA-F0-9]{4})")
     #   u = p.parse("http://example.jp/%uABCD") #=> #<URI::HTTP http://example.jp/%uABCD>
     #   URI.parse(u.to_s) #=> raises URI::InvalidURIError
     #
@@ -108,12 +108,12 @@ def initialize(opts = {})
 
     # The Hash of patterns.
     #
-    # See also URI::Parser.initialize_pattern.
+    # See also #initialize_pattern.
     attr_reader :pattern
 
     # The Hash of Regexp.
     #
-    # See also URI::Parser.initialize_regexp.
+    # See also #initialize_regexp.
     attr_reader :regexp
 
     # Returns a split URI against +regexp[:ABS_URI]+.
@@ -202,8 +202,7 @@ def split(uri)
     #
     # == Usage
     #
-    #   p = URI::Parser.new
-    #   p.parse("ldap://ldap.example.com/dc=example?user=john")
+    #   URI::RFC2396_PARSER.parse("ldap://ldap.example.com/dc=example?user=john")
     #   #=> #<URI::LDAP ldap://ldap.example.com/dc=example?user=john>
     #
     def parse(uri)
@@ -244,7 +243,7 @@ def join(*uris)
     # If no +block+ given, then returns the result,
     # else it calls +block+ for each element in result.
     #
-    # See also URI::Parser.make_regexp.
+    # See also #make_regexp.
     #
     def extract(str, schemes = nil)
       if block_given?
@@ -263,7 +262,7 @@ def make_regexp(schemes = nil)
       unless schemes
         @regexp[:ABS_URI_REF]
       else
-        /(?=#{Regexp.union(*schemes)}:)#{@pattern[:X_ABS_URI]}/x
+        /(?=(?i:#{Regexp.union(*schemes).source}):)#{@pattern[:X_ABS_URI]}/x
       end
     end
 
@@ -321,14 +320,14 @@ def unescape(str, escaped = @regexp[:ESCAPED])
       str.gsub(escaped) { [$&[1, 2]].pack('H2').force_encoding(enc) }
     end
 
-    @@to_s = Kernel.instance_method(:to_s)
-    if @@to_s.respond_to?(:bind_call)
-      def inspect
-        @@to_s.bind_call(self)
+    TO_S = Kernel.instance_method(:to_s) # :nodoc:
+    if TO_S.respond_to?(:bind_call)
+      def inspect # :nodoc:
+        TO_S.bind_call(self)
       end
     else
-      def inspect
-        @@to_s.bind(self).call
+      def inspect # :nodoc:
+        TO_S.bind(self).call
       end
     end
 
@@ -524,6 +523,8 @@ def initialize_regexp(pattern)
       ret
     end
 
+    # Returns +uri+ as-is if it is URI, or convert it to URI if it is
+    # a String.
     def convert_to_uri(uri)
       if uri.is_a?(URI::Generic)
         uri
@@ -536,4 +537,11 @@ def convert_to_uri(uri)
     end
 
   end # class Parser
+
+  # Backward compatibility for URI::REGEXP::PATTERN::*
+  RFC2396_Parser.new.pattern.each_pair do |sym, str|
+    unless RFC2396_REGEXP::PATTERN.const_defined?(sym, false)
+      RFC2396_REGEXP::PATTERN.const_set(sym, str)
+    end
+  end
 end # module URI
diff --git a/lib/uri/rfc3986_parser.rb b/lib/uri/rfc3986_parser.rb
index 4000f13..0b5f0c4 100644
--- a/lib/uri/rfc3986_parser.rb
+++ b/lib/uri/rfc3986_parser.rb
@@ -142,25 +142,25 @@ def join(*uris) # :nodoc:
 
     # Compatibility for RFC2396 parser
     def extract(str, schemes = nil, &block) # :nodoc:
-      warn "URI::RFC3986_PARSER.extract is obsoleted. Use URI::RFC2396_PARSER.extract explicitly.", uplevel: 1 if $VERBOSE
+      warn "URI::RFC3986_PARSER.extract is obsolete. Use URI::RFC2396_PARSER.extract explicitly.", uplevel: 1 if $VERBOSE
       RFC2396_PARSER.extract(str, schemes, &block)
     end
 
     # Compatibility for RFC2396 parser
     def make_regexp(schemes = nil) # :nodoc:
-      warn "URI::RFC3986_PARSER.make_regexp is obsoleted. Use URI::RFC2396_PARSER.make_regexp explicitly.", uplevel: 1 if $VERBOSE
+      warn "URI::RFC3986_PARSER.make_regexp is obsolete. Use URI::RFC2396_PARSER.make_regexp explicitly.", uplevel: 1 if $VERBOSE
       RFC2396_PARSER.make_regexp(schemes)
     end
 
     # Compatibility for RFC2396 parser
     def escape(str, unsafe = nil) # :nodoc:
-      warn "URI::RFC3986_PARSER.escape is obsoleted. Use URI::RFC2396_PARSER.escape explicitly.", uplevel: 1 if $VERBOSE
+      warn "URI::RFC3986_PARSER.escape is obsolete. Use URI::RFC2396_PARSER.escape explicitly.", uplevel: 1 if $VERBOSE
       unsafe ? RFC2396_PARSER.escape(str, unsafe) : RFC2396_PARSER.escape(str)
     end
 
     # Compatibility for RFC2396 parser
     def unescape(str, escaped = nil) # :nodoc:
-      warn "URI::RFC3986_PARSER.unescape is obsoleted. Use URI::RFC2396_PARSER.unescape explicitly.", uplevel: 1 if $VERBOSE
+      warn "URI::RFC3986_PARSER.unescape is obsolete. Use URI::RFC2396_PARSER.unescape explicitly.", uplevel: 1 if $VERBOSE
       escaped ? RFC2396_PARSER.unescape(str, escaped) : RFC2396_PARSER.unescape(str)
     end
 
diff --git a/lib/uri/version.rb b/lib/uri/version.rb
index c68c43a..b6a8ce1 100644
--- a/lib/uri/version.rb
+++ b/lib/uri/version.rb
@@ -1,6 +1,6 @@
 module URI
   # :stopdoc:
-  VERSION_CODE = '010000'.freeze
+  VERSION_CODE = '010003'.freeze
   VERSION = VERSION_CODE.scan(/../).collect{|n| n.to_i}.join('.').freeze
   # :startdoc:
 end
diff --git a/test/uri/test_common.rb b/test/uri/test_common.rb
index bccdeaf..1291366 100644
--- a/test/uri/test_common.rb
+++ b/test/uri/test_common.rb
@@ -10,13 +10,23 @@ def setup
   def teardown
   end
 
+  EnvUtil.suppress_warning do
+    class Foo
+      # Intentionally use `URI::REGEXP`, which is for the compatibility
+      include URI::REGEXP::PATTERN
+    end
+  end
+
   def test_fallback_constants
-    orig_verbose = $VERBOSE
-    $VERBOSE = nil
-    assert URI::ABS_URI
-    assert_raise(NameError) { URI::FOO }
-  ensure
-    $VERBOSE = orig_verbose
+    EnvUtil.suppress_warning do
+      assert_raise(NameError) { URI::FOO }
+
+      assert_equal URI::ABS_URI, URI::RFC2396_PARSER.regexp[:ABS_URI]
+      assert_equal URI::PATTERN, URI::RFC2396_Parser::PATTERN
+      assert_equal URI::REGEXP, URI::RFC2396_REGEXP
+      assert_equal URI::REGEXP::PATTERN, URI::RFC2396_REGEXP::PATTERN
+      assert_equal Foo::IPV4ADDR, URI::RFC2396_REGEXP::PATTERN::IPV4ADDR
+    end
   end
 
   def test_parser_switch
@@ -30,6 +40,7 @@ def test_parser_switch
     assert defined?(URI::REGEXP)
     assert defined?(URI::PATTERN)
     assert defined?(URI::PATTERN::ESCAPED)
+    assert defined?(URI::REGEXP::PATTERN::IPV6ADDR)
 
     URI.parser = URI::RFC3986_PARSER
 
@@ -64,7 +75,7 @@ def test_ractor
     return unless defined?(Ractor)
     assert_ractor(<<~RUBY, require: 'uri')
       r = Ractor.new { URI.parse("https://ruby-lang.org/").inspect }
-      assert_equal(URI.parse("https://ruby-lang.org/").inspect, r.take)
+      assert_equal(URI.parse("https://ruby-lang.org/").inspect, r.value)
     RUBY
   end
 
@@ -102,17 +113,18 @@ def test_register_scheme_lowercase
 
   def test_register_scheme_with_symbols
     # Valid schemes from https://www.iana.org/assignments/uri-schemes/uri-schemes.xhtml
-    some_uri_class = Class.new(URI::Generic)
-    assert_raise(NameError) { URI.register_scheme 'ms-search', some_uri_class }
-    assert_raise(NameError) { URI.register_scheme 'microsoft.windows.camera', some_uri_class }
-    assert_raise(NameError) { URI.register_scheme 'coaps+ws', some_uri_class }
+    list = []
+    %w[ms-search microsoft.windows.camera coaps+ws].each {|name|
+      list << [name, URI.register_scheme(name, Class.new(URI::Generic))]
+    }
 
-    ms_search_class = Class.new(URI::Generic)
-    URI.register_scheme 'MS_SEARCH', ms_search_class
-    begin
-      assert_equal URI::Generic, URI.parse('ms-search://localhost').class
-    ensure
-      URI.const_get(:Schemes).send(:remove_const, :MS_SEARCH)
+    list.each do |scheme, uri_class|
+      assert_equal uri_class, URI.parse("#{scheme}://localhost").class
+    end
+  ensure
+    schemes = URI.const_get(:Schemes)
+    list.each do |scheme, |
+      schemes.send(:remove_const, schemes.escape(scheme))
     end
   end
 
diff --git a/test/uri/test_ftp.rb b/test/uri/test_ftp.rb
index f45bb06..3ad7864 100644
--- a/test/uri/test_ftp.rb
+++ b/test/uri/test_ftp.rb
@@ -33,11 +33,11 @@ def test_paths
     # If you think what's below is wrong, please read RubyForge bug 2055,
     # RFC 1738 section 3.2.2, and RFC 2396.
     u = URI.parse('ftp://ftp.example.com/foo/bar/file.ext')
-    assert(u.path == 'foo/bar/file.ext')
+    assert_equal('foo/bar/file.ext', u.path)
     u = URI.parse('ftp://ftp.example.com//foo/bar/file.ext')
-    assert(u.path == '/foo/bar/file.ext')
+    assert_equal('/foo/bar/file.ext', u.path)
     u = URI.parse('ftp://ftp.example.com/%2Ffoo/bar/file.ext')
-    assert(u.path == '/foo/bar/file.ext')
+    assert_equal('/foo/bar/file.ext', u.path)
   end
 
   def test_assemble
@@ -45,8 +45,8 @@ def test_assemble
     # assuming everyone else has implemented RFC 2396.
     uri = URI::FTP.build(['user:password', 'ftp.example.com', nil,
                          '/path/file.zip', 'i'])
-    assert(uri.to_s ==
-           'ftp://user:password@ftp.example.com/%2Fpath/file.zip;type=i')
+    assert_equal('ftp://user:password@ftp.example.com/%2Fpath/file.zip;type=i',
+                 uri.to_s)
   end
 
   def test_select
diff --git a/test/uri/test_generic.rb b/test/uri/test_generic.rb
index 8209363..c725116 100644
--- a/test/uri/test_generic.rb
+++ b/test/uri/test_generic.rb
@@ -175,6 +175,17 @@ def test_parse
     # must be empty string to identify as path-abempty, not path-absolute
     assert_equal('', url.host)
     assert_equal('http:////example.com', url.to_s)
+
+    # sec-2957667
+    url = URI.parse('http://user:pass@example.com').merge('//example.net')
+    assert_equal('http://example.net', url.to_s)
+    assert_nil(url.userinfo)
+    url = URI.join('http://user:pass@example.com', '//example.net')
+    assert_equal('http://example.net', url.to_s)
+    assert_nil(url.userinfo)
+    url = URI.parse('http://user:pass@example.com') + '//example.net'
+    assert_equal('http://example.net', url.to_s)
+    assert_nil(url.userinfo)
   end
 
   def test_parse_scheme_with_symbols
@@ -229,9 +240,9 @@ def test_merge
     u = URI.parse('http://foo/bar/baz')
     assert_equal(nil, u.merge!(""))
     assert_equal(nil, u.merge!(u))
-    assert(nil != u.merge!("."))
+    refute_nil(u.merge!("."))
     assert_equal('http://foo/bar/', u.to_s)
-    assert(nil != u.merge!("../baz"))
+    refute_nil(u.merge!("../baz"))
     assert_equal('http://foo/baz', u.to_s)
 
     url = URI.parse('http://a/b//c') + 'd//e'
@@ -267,6 +278,13 @@ def test_merge
     assert_equal(u0, u1)
   end
 
+  def test_merge_authority
+    u = URI.parse('http://user:pass@example.com:8080')
+    u0 = URI.parse('http://new.example.org/path')
+    u1 = u.merge('//new.example.org/path')
+    assert_equal(u0, u1)
+  end
+
   def test_route
     url = URI.parse('http://hoge/a.html').route_to('http://hoge/b.html')
     assert_equal('b.html', url.to_s)
@@ -338,7 +356,7 @@ def test_rfc3986_examples
     assert_equal('http://a/b/c/g', url.to_s)
     url = @base_url.route_to('http://a/b/c/g')
     assert_kind_of(URI::Generic, url)
-    assert('./g' != url.to_s) # ok
+    refute_equal('./g', url.to_s) # ok
     assert_equal('g', url.to_s)
 
 #  http://a/b/c/d;p?q
@@ -357,7 +375,7 @@ def test_rfc3986_examples
     assert_equal('http://a/g', url.to_s)
     url = @base_url.route_to('http://a/g')
     assert_kind_of(URI::Generic, url)
-    assert('/g' != url.to_s) # ok
+    refute_equal('/g', url.to_s) # ok
     assert_equal('../../g', url.to_s)
 
 #  http://a/b/c/d;p?q
@@ -448,7 +466,7 @@ def test_rfc3986_examples
     assert_equal('http://a/b/c/', url.to_s)
     url = @base_url.route_to('http://a/b/c/')
     assert_kind_of(URI::Generic, url)
-    assert('.' != url.to_s) # ok
+    refute_equal('.', url.to_s) # ok
     assert_equal('./', url.to_s)
 
 #  http://a/b/c/d;p?q
@@ -467,7 +485,7 @@ def test_rfc3986_examples
     assert_equal('http://a/b/', url.to_s)
     url = @base_url.route_to('http://a/b/')
     assert_kind_of(URI::Generic, url)
-    assert('..' != url.to_s) # ok
+    refute_equal('..', url.to_s) # ok
     assert_equal('../', url.to_s)
 
 #  http://a/b/c/d;p?q
@@ -495,7 +513,7 @@ def test_rfc3986_examples
     assert_equal('http://a/', url.to_s)
     url = @base_url.route_to('http://a/')
     assert_kind_of(URI::Generic, url)
-    assert('../..' != url.to_s) # ok
+    refute_equal('../..', url.to_s) # ok
     assert_equal('../../', url.to_s)
 
 #  http://a/b/c/d;p?q
@@ -586,7 +604,7 @@ def test_rfc3986_examples
     assert_equal('http://a/g', url.to_s)
     url = @base_url.route_to('http://a/g')
     assert_kind_of(URI::Generic, url)
-    assert('../../../g' != url.to_s)  # ok? yes, it confuses you
+    refute_equal('../../../g', url.to_s)  # ok? yes, it confuses you
     assert_equal('../../g', url.to_s) # and it is clearly
 
 #  http://a/b/c/d;p?q
@@ -596,7 +614,7 @@ def test_rfc3986_examples
     assert_equal('http://a/g', url.to_s)
     url = @base_url.route_to('http://a/g')
     assert_kind_of(URI::Generic, url)
-    assert('../../../../g' != url.to_s) # ok? yes, it confuses you
+    refute_equal('../../../../g', url.to_s) # ok? yes, it confuses you
     assert_equal('../../g', url.to_s)   # and it is clearly
 
 #  http://a/b/c/d;p?q
@@ -606,7 +624,7 @@ def test_rfc3986_examples
     assert_equal('http://a/b/g', url.to_s)
     url = @base_url.route_to('http://a/b/g')
     assert_kind_of(URI::Generic, url)
-    assert('./../g' != url.to_s) # ok
+    refute_equal('./../g', url.to_s) # ok
     assert_equal('../g', url.to_s)
 
 #  http://a/b/c/d;p?q
@@ -616,7 +634,7 @@ def test_rfc3986_examples
     assert_equal('http://a/b/c/g/', url.to_s)
     url = @base_url.route_to('http://a/b/c/g/')
     assert_kind_of(URI::Generic, url)
-    assert('./g/.' != url.to_s) # ok
+    refute_equal('./g/.', url.to_s) # ok
     assert_equal('g/', url.to_s)
 
 #  http://a/b/c/d;p?q
@@ -626,7 +644,7 @@ def test_rfc3986_examples
     assert_equal('http://a/b/c/g/h', url.to_s)
     url = @base_url.route_to('http://a/b/c/g/h')
     assert_kind_of(URI::Generic, url)
-    assert('g/./h' != url.to_s) # ok
+    refute_equal('g/./h', url.to_s) # ok
     assert_equal('g/h', url.to_s)
 
 #  http://a/b/c/d;p?q
@@ -636,7 +654,7 @@ def test_rfc3986_examples
     assert_equal('http://a/b/c/h', url.to_s)
     url = @base_url.route_to('http://a/b/c/h')
     assert_kind_of(URI::Generic, url)
-    assert('g/../h' != url.to_s) # ok
+    refute_equal('g/../h', url.to_s) # ok
     assert_equal('h', url.to_s)
 
 #  http://a/b/c/d;p?q
@@ -646,7 +664,7 @@ def test_rfc3986_examples
     assert_equal('http://a/b/c/g;x=1/y', url.to_s)
     url = @base_url.route_to('http://a/b/c/g;x=1/y')
     assert_kind_of(URI::Generic, url)
-    assert('g;x=1/./y' != url.to_s) # ok
+    refute_equal('g;x=1/./y', url.to_s) # ok
     assert_equal('g;x=1/y', url.to_s)
 
 #  http://a/b/c/d;p?q
@@ -656,7 +674,7 @@ def test_rfc3986_examples
     assert_equal('http://a/b/c/y', url.to_s)
     url = @base_url.route_to('http://a/b/c/y')
     assert_kind_of(URI::Generic, url)
-    assert('g;x=1/../y' != url.to_s) # ok
+    refute_equal('g;x=1/../y', url.to_s) # ok
     assert_equal('y', url.to_s)
 
 #  http://a/b/c/d;p?q
@@ -804,18 +822,18 @@ def test_hierarchical
     hierarchical = URI.parse('http://a.b.c/example')
     opaque = URI.parse('mailto:mduerst@ifi.unizh.ch')
 
-    assert hierarchical.hierarchical?
-    refute opaque.hierarchical?
+    assert_predicate hierarchical, :hierarchical?
+    refute_predicate opaque, :hierarchical?
   end
 
   def test_absolute
     abs_uri = URI.parse('http://a.b.c/')
     not_abs = URI.parse('a.b.c')
 
-    refute not_abs.absolute?
+    refute_predicate not_abs, :absolute?
 
-    assert abs_uri.absolute
-    assert abs_uri.absolute?
+    assert_predicate abs_uri, :absolute
+    assert_predicate abs_uri, :absolute?
   end
 
   def test_ipv6
@@ -828,8 +846,10 @@ def test_ipv6
     assert_equal("http://[::1]/bar", u.to_s)
     u.hostname = "::1"
     assert_equal("http://[::1]/bar", u.to_s)
-    u.hostname = ""
-    assert_equal("http:///bar", u.to_s)
+
+    u = URI("file://foo/bar")
+    u.hostname = ''
+    assert_equal("file:///bar", u.to_s)
   end
 
   def test_build
@@ -850,6 +870,19 @@ def test_build
     assert_equal("http://[::1]/bar/baz", u.to_s)
     assert_equal("[::1]", u.host)
     assert_equal("::1", u.hostname)
+
+    assert_raise_with_message(ArgumentError, /URI::Generic/) {
+      URI::Generic.build(nil)
+    }
+
+    c = Class.new(URI::Generic) do
+      def self.component; raise; end
+    end
+    expected = /\(#{URI::Generic::COMPONENT.join(', ')}\)/
+    message = "fallback to URI::Generic::COMPONENT if component raised"
+    assert_raise_with_message(ArgumentError, expected, message) {
+      c.build(nil)
+    }
   end
 
   def test_build2
diff --git a/test/uri/test_http.rb b/test/uri/test_http.rb
index e937b1a..8816d20 100644
--- a/test/uri/test_http.rb
+++ b/test/uri/test_http.rb
@@ -19,6 +19,10 @@ def test_build
     assert_kind_of(URI::HTTP, u)
   end
 
+  def test_build_empty_host
+    assert_raise(URI::InvalidComponentError) { URI::HTTP.build(host: '') }
+  end
+
   def test_parse
     u = URI.parse('http://a')
     assert_kind_of(URI::HTTP, u)
@@ -33,19 +37,19 @@ def test_normalize
     host = 'aBcD'
     u1 = URI.parse('http://' + host + '/eFg?HiJ')
     u2 = URI.parse('http://' + host.downcase + '/eFg?HiJ')
-    assert(u1.normalize.host == 'abcd')
-    assert(u1.normalize.path == u1.path)
-    assert(u1.normalize == u2.normalize)
-    assert(!u1.normalize.host.equal?(u1.host))
-    assert( u2.normalize.host.equal?(u2.host))
+    assert_equal('abcd', u1.normalize.host)
+    assert_equal(u1.path, u1.normalize.path)
+    assert_equal(u2.normalize, u1.normalize)
+    refute_same(u1.host, u1.normalize.host)
+    assert_same(u2.host, u2.normalize.host)
 
     assert_equal('http://abc/', URI.parse('http://abc').normalize.to_s)
   end
 
   def test_equal
-    assert(URI.parse('http://abc') == URI.parse('http://ABC'))
-    assert(URI.parse('http://abc/def') == URI.parse('http://ABC/def'))
-    assert(URI.parse('http://abc/def') != URI.parse('http://ABC/DEF'))
+    assert_equal(URI.parse('http://ABC'), URI.parse('http://abc'))
+    assert_equal(URI.parse('http://ABC/def'), URI.parse('http://abc/def'))
+    refute_equal(URI.parse('http://ABC/DEF'), URI.parse('http://abc/def'))
   end
 
   def test_request_uri
diff --git a/test/uri/test_mailto.rb b/test/uri/test_mailto.rb
index e7d3142..59bb5de 100644
--- a/test/uri/test_mailto.rb
+++ b/test/uri/test_mailto.rb
@@ -141,6 +141,11 @@ def test_initializer
   def test_check_to
     u = URI::MailTo.build(['joe@example.com', 'subject=Ruby'])
 
+    # Valid emails
+    u.to = 'a@valid.com'
+    assert_equal(u.to, 'a@valid.com')
+
+    # Invalid emails
     assert_raise(URI::InvalidComponentError) do
       u.to = '#1@mail.com'
     end
@@ -148,6 +153,79 @@ def test_check_to
     assert_raise(URI::InvalidComponentError) do
       u.to = '@invalid.email'
     end
+
+    assert_raise(URI::InvalidComponentError) do
+      u.to = '.hello@invalid.email'
+    end
+
+    assert_raise(URI::InvalidComponentError) do
+      u.to = 'hello.@invalid.email'
+    end
+
+    assert_raise(URI::InvalidComponentError) do
+      u.to = 'n.@invalid.email'
+    end
+
+    assert_raise(URI::InvalidComponentError) do
+      u.to = 'n..t@invalid.email'
+    end
+
+    # Invalid host emails
+    assert_raise(URI::InvalidComponentError) do
+      u.to = 'a@.invalid.email'
+    end
+
+    assert_raise(URI::InvalidComponentError) do
+      u.to = 'a@invalid.email.'
+    end
+
+    assert_raise(URI::InvalidComponentError) do
+      u.to = 'a@invalid..email'
+    end
+
+    assert_raise(URI::InvalidComponentError) do
+      u.to = 'a@-invalid.email'
+    end
+
+    assert_raise(URI::InvalidComponentError) do
+      u.to = 'a@invalid-.email'
+    end
+
+    assert_raise(URI::InvalidComponentError) do
+      u.to = 'a@invalid.-email'
+    end
+
+    assert_raise(URI::InvalidComponentError) do
+      u.to = 'a@invalid.email-'
+    end
+
+    u.to = 'a@'+'invalid'.ljust(63, 'd')+'.email'
+    assert_raise(URI::InvalidComponentError) do
+      u.to = 'a@'+'invalid'.ljust(64, 'd')+'.email'
+    end
+
+    u.to = 'a@invalid.'+'email'.rjust(63, 'e')
+    assert_raise(URI::InvalidComponentError) do
+      u.to = 'a@invalid.'+'email'.rjust(64, 'e')
+    end
+  end
+
+  def test_email_regexp
+    re = URI::MailTo::EMAIL_REGEXP
+
+    repeat = 10
+    longlabel = '.' + 'invalid'.ljust(63, 'd')
+    endlabel = ''
+    seq = (1..3).map {|i| 10**i}
+    rehearsal = 10
+    pre = ->(n) {'a@invalid' + longlabel*(n) + endlabel}
+    assert_linear_performance(seq, rehearsal: rehearsal, pre: pre) do |to|
+      repeat.times {re =~ to or flunk}
+    end
+    endlabel = '.' + 'email'.rjust(64, 'd')
+    assert_linear_performance(seq, rehearsal: rehearsal, pre: pre) do |to|
+      repeat.times {re =~ to and flunk}
+    end
   end
 
   def test_to_s
diff --git a/test/uri/test_parser.rb b/test/uri/test_parser.rb
index f455a5c..c14824f 100644
--- a/test/uri/test_parser.rb
+++ b/test/uri/test_parser.rb
@@ -20,17 +20,17 @@ def test_compare
     u2 = p.parse(url)
     u3 = p.parse(url)
 
-    assert(u0 == u1)
-    assert(u0.eql?(u1))
-    assert(!u0.equal?(u1))
+    assert_equal(u1, u0)
+    assert_send([u0, :eql?, u1])
+    refute_same(u1, u0)
 
-    assert(u1 == u2)
-    assert(!u1.eql?(u2))
-    assert(!u1.equal?(u2))
+    assert_equal(u2, u1)
+    assert_not_send([u1, :eql?, u2])
+    refute_same(u1, u2)
 
-    assert(u2 == u3)
-    assert(u2.eql?(u3))
-    assert(!u2.equal?(u3))
+    assert_equal(u3, u2)
+    assert_send([u2, :eql?, u3])
+    refute_same(u3, u2)
   end
 
   def test_parse_rfc2396_parser
@@ -113,4 +113,12 @@ def test_rfc3986_port_check
       end
     end
   end
+
+  def test_rfc2822_make_regexp
+    parser = URI::RFC2396_Parser.new
+    regexp = parser.make_regexp("HTTP")
+    assert_match(regexp, "HTTP://EXAMPLE.COM/")
+    assert_match(regexp, "http://example.com/")
+    refute_match(regexp, "https://example.com/")
+  end
 end
diff --git a/test/uri/test_ws.rb b/test/uri/test_ws.rb
index f3918f6..d63ebd4 100644
--- a/test/uri/test_ws.rb
+++ b/test/uri/test_ws.rb
@@ -31,19 +31,19 @@ def test_normalize
     host = 'aBcD'
     u1 = URI.parse('ws://' + host          + '/eFg?HiJ')
     u2 = URI.parse('ws://' + host.downcase + '/eFg?HiJ')
-    assert(u1.normalize.host == 'abcd')
-    assert(u1.normalize.path == u1.path)
-    assert(u1.normalize == u2.normalize)
-    assert(!u1.normalize.host.equal?(u1.host))
-    assert( u2.normalize.host.equal?(u2.host))
+    assert_equal('abcd', u1.normalize.host)
+    assert_equal(u1.path, u1.normalize.path)
+    assert_equal(u2.normalize, u1.normalize)
+    refute_same(u1.host, u1.normalize.host)
+    assert_same(u2.host, u2.normalize.host)
 
     assert_equal('ws://abc/', URI.parse('ws://abc').normalize.to_s)
   end
 
   def test_equal
-    assert(URI.parse('ws://abc') == URI.parse('ws://ABC'))
-    assert(URI.parse('ws://abc/def') == URI.parse('ws://ABC/def'))
-    assert(URI.parse('ws://abc/def') != URI.parse('ws://ABC/DEF'))
+    assert_equal(URI.parse('ws://ABC'), URI.parse('ws://abc'))
+    assert_equal(URI.parse('ws://ABC/def'), URI.parse('ws://abc/def'))
+    refute_equal(URI.parse('ws://ABC/DEF'), URI.parse('ws://abc/def'))
   end
 
   def test_request_uri
diff --git a/test/uri/test_wss.rb b/test/uri/test_wss.rb
index 13a2583..cbef327 100644
--- a/test/uri/test_wss.rb
+++ b/test/uri/test_wss.rb
@@ -31,19 +31,19 @@ def test_normalize
     host = 'aBcD'
     u1 = URI.parse('wss://' + host          + '/eFg?HiJ')
     u2 = URI.parse('wss://' + host.downcase + '/eFg?HiJ')
-    assert(u1.normalize.host == 'abcd')
-    assert(u1.normalize.path == u1.path)
-    assert(u1.normalize == u2.normalize)
-    assert(!u1.normalize.host.equal?(u1.host))
-    assert( u2.normalize.host.equal?(u2.host))
+    assert_equal('abcd', u1.normalize.host)
+    assert_equal(u1.path, u1.normalize.path)
+    assert_equal(u2.normalize, u1.normalize)
+    refute_same(u1.host, u1.normalize.host)
+    assert_same(u2.host, u2.normalize.host)
 
     assert_equal('wss://abc/', URI.parse('wss://abc').normalize.to_s)
   end
 
   def test_equal
-    assert(URI.parse('wss://abc') == URI.parse('wss://ABC'))
-    assert(URI.parse('wss://abc/def') == URI.parse('wss://ABC/def'))
-    assert(URI.parse('wss://abc/def') != URI.parse('wss://ABC/DEF'))
+    assert_equal(URI.parse('wss://ABC'), URI.parse('wss://abc'))
+    assert_equal(URI.parse('wss://ABC/def'), URI.parse('wss://abc/def'))
+    refute_equal(URI.parse('wss://ABC/DEF'), URI.parse('wss://abc/def'))
   end
 
   def test_request_uri
diff --git a/uri.gemspec b/uri.gemspec
index 9cf0a71..0d0f897 100644
--- a/uri.gemspec
+++ b/uri.gemspec
@@ -30,8 +30,11 @@ Gem::Specification.new do |spec|
 
   # Specify which files should be added to the gem when it is released.
   # The `git ls-files -z` loads the files in the RubyGem that have been added into git.
+  gemspec = File.basename(__FILE__)
   spec.files         = Dir.chdir(File.expand_path('..', __FILE__)) do
-    `git ls-files -z 2>#{IO::NULL}`.split("\x0").reject { |f| f.match(%r{^(test|spec|features)/}) }
+    `git ls-files -z 2>#{IO::NULL}`.split("\x0").reject do |file|
+      (file == gemspec) || file.start_with?(*%w[bin/ test/ rakelib/ .github/ .gitignore Gemfile Rakefile])
+    end
   end
   spec.bindir        = "exe"
   spec.executables   = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }