diff --git a/tests/lib/core_assertions.rb b/tests/lib/core_assertions.rb
index abd0e450..358e7d95 100644
--- a/tests/lib/core_assertions.rb
+++ b/tests/lib/core_assertions.rb
@@ -1,8 +1,49 @@
 # frozen_string_literal: true
 
 module Test
+
+  class << self
+    ##
+    # Filter object for backtraces.
+
+    attr_accessor :backtrace_filter
+  end
+
+  class BacktraceFilter # :nodoc:
+    def filter bt
+      return ["No backtrace"] unless bt
+
+      new_bt = []
+      pattern = %r[/(?:lib\/test/|core_assertions\.rb:)]
+
+      unless $DEBUG then
+        bt.each do |line|
+          break if pattern.match?(line)
+          new_bt << line
+        end
+
+        new_bt = bt.reject { |line| pattern.match?(line) } if new_bt.empty?
+        new_bt = bt.dup if new_bt.empty?
+      else
+        new_bt = bt.dup
+      end
+
+      new_bt
+    end
+  end
+
+  self.backtrace_filter = BacktraceFilter.new
+
+  def self.filter_backtrace bt # :nodoc:
+    backtrace_filter.filter bt
+  end
+
   module Unit
     module Assertions
+      def assert_raises(*exp, &b)
+        raise NoMethodError, "use assert_raise", caller
+      end
+
       def _assertions= n # :nodoc:
         @_assertions = n
       end
@@ -16,31 +57,24 @@ def _assertions # :nodoc:
 
       def message msg = nil, ending = nil, &default
         proc {
-          msg = msg.call.chomp(".") if Proc === msg
-          custom_message = "#{msg}.\n" unless msg.nil? or msg.to_s.empty?
-          "#{custom_message}#{default.call}#{ending || "."}"
+          ending ||= (ending_pattern = /(?<!\.)\z/; ".")
+          ending_pattern ||= /(?<!#{Regexp.quote(ending)})\z/
+          msg = msg.call if Proc === msg
+          ary = [msg, (default.call if default)].compact.reject(&:empty?)
+          ary.map! {|str| str.to_s.sub(ending_pattern, ending) }
+          begin
+            ary.join("\n")
+          rescue Encoding::CompatibilityError
+            ary.map(&:b).join("\n")
+          end
         }
       end
     end
 
     module CoreAssertions
-      if defined?(MiniTest)
-        require_relative '../../envutil'
-        # for ruby core testing
-        include MiniTest::Assertions
-
-        # Compatibility hack for assert_raise
-        Test::Unit::AssertionFailedError = MiniTest::Assertion
-      else
-        module MiniTest
-          class Assertion < Exception; end
-          class Skip < Assertion; end
-        end
-
-        require 'pp'
-        require_relative 'envutil'
-        include Test::Unit::Assertions
-      end
+      require_relative 'envutil'
+      require 'pp'
+      nil.pretty_inspect
 
       def mu_pp(obj) #:nodoc:
         obj.pretty_inspect.chomp
@@ -114,19 +148,19 @@ def syntax_check(code, fname, line)
       end
 
       def assert_no_memory_leak(args, prepare, code, message=nil, limit: 2.0, rss: false, **opt)
-        # TODO: consider choosing some appropriate limit for MJIT and stop skipping this once it does not randomly fail
+        # TODO: consider choosing some appropriate limit for RJIT and stop skipping this once it does not randomly fail
+        pend 'assert_no_memory_leak may consider RJIT memory usage as leak' if defined?(RubyVM::RJIT) && RubyVM::RJIT.enabled?
+        # For previous versions which implemented MJIT
         pend 'assert_no_memory_leak may consider MJIT memory usage as leak' if defined?(RubyVM::MJIT) && RubyVM::MJIT.enabled?
 
-        require_relative '../../memory_status'
-        raise MiniTest::Skip, "unsupported platform" unless defined?(Memory::Status)
+        require_relative 'memory_status'
+        raise Test::Unit::PendedError, "unsupported platform" unless defined?(Memory::Status)
 
-        token = "\e[7;1m#{$$.to_s}:#{Time.now.strftime('%s.%L')}:#{rand(0x10000).to_s(16)}:\e[m"
-        token_dump = token.dump
-        token_re = Regexp.quote(token)
+        token_dump, token_re = new_test_token
         envs = args.shift if Array === args and Hash === args.first
         args = [
           "--disable=gems",
-          "-r", File.expand_path("../../../memory_status", __FILE__),
+          "-r", File.expand_path("../memory_status", __FILE__),
           *args,
           "-v", "-",
         ]
@@ -182,27 +216,15 @@ def assert_nothing_raised(*args)
           msg = args.pop
         end
         begin
-          line = __LINE__; yield
-        rescue MiniTest::Skip
+          yield
+        rescue Test::Unit::PendedError, *(Test::Unit::AssertionFailedError if args.empty?)
           raise
-        rescue Exception => e
-          bt = e.backtrace
-          as = e.instance_of?(MiniTest::Assertion)
-          if as
-            ans = /\A#{Regexp.quote(__FILE__)}:#{line}:in /o
-            bt.reject! {|ln| ans =~ ln}
-          end
-          if ((args.empty? && !as) ||
-              args.any? {|a| a.instance_of?(Module) ? e.is_a?(a) : e.class == a })
-            msg = message(msg) {
-              "Exception raised:\n<#{mu_pp(e)}>\n" +
-              "Backtrace:\n" +
-              e.backtrace.map{|frame| "  #{frame}"}.join("\n")
-            }
-            raise MiniTest::Assertion, msg.call, bt
-          else
-            raise
-          end
+        rescue *(args.empty? ? Exception : args) => e
+          msg = message(msg) {
+            "Exception raised:\n<#{mu_pp(e)}>\n""Backtrace:\n" <<
+            Test.filter_backtrace(e.backtrace).map{|frame| "  #{frame}"}.join("\n")
+          }
+          raise Test::Unit::AssertionFailedError, msg.call, e.backtrace
         end
       end
 
@@ -259,12 +281,17 @@ def assert_ruby_status(args, test_stdin="", message=nil, **opt)
 
       ABORT_SIGNALS = Signal.list.values_at(*%w"ILL ABRT BUS SEGV TERM")
 
-      def separated_runner(out = nil)
+      def separated_runner(token, out = nil)
+        include(*Test::Unit::TestCase.ancestors.select {|c| !c.is_a?(Class) })
         out = out ? IO.new(out, 'w') : STDOUT
         at_exit {
-          out.puts [Marshal.dump($!)].pack('m'), "assertions=\#{self._assertions}"
+          out.puts "#{token}<error>", [Marshal.dump($!)].pack('m'), "#{token}</error>", "#{token}assertions=#{self._assertions}"
         }
-        Test::Unit::Runner.class_variable_set(:@@stop_auto_run, true) if defined?(Test::Unit::Runner)
+        if defined?(Test::Unit::Runner)
+          Test::Unit::Runner.class_variable_set(:@@stop_auto_run, true)
+        elsif defined?(Test::Unit::AutoRunner)
+          Test::Unit::AutoRunner.need_auto_run = false
+        end
       end
 
       def assert_separately(args, file = nil, line = nil, src, ignore_stderr: nil, **opt)
@@ -274,22 +301,24 @@ def assert_separately(args, file = nil, line = nil, src, ignore_stderr: nil, **o
           line ||= loc.lineno
         end
         capture_stdout = true
-        unless /mswin|mingw/ =~ RUBY_PLATFORM
+        unless /mswin|mingw/ =~ RbConfig::CONFIG['host_os']
           capture_stdout = false
-          opt[:out] = MiniTest::Unit.output if defined?(MiniTest::Unit)
+          opt[:out] = Test::Unit::Runner.output if defined?(Test::Unit::Runner)
           res_p, res_c = IO.pipe
-          opt[res_c.fileno] = res_c.fileno
+          opt[:ios] = [res_c]
         end
+        token_dump, token_re = new_test_token
         src = <<eom
 # -*- coding: #{line += __LINE__; src.encoding}; -*-
 BEGIN {
-  require "test/unit";include Test::Unit::Assertions;require #{(__dir__ + "/core_assertions").dump};include Test::Unit::CoreAssertions
-  separated_runner #{res_c&.fileno}
+  require "test/unit";include Test::Unit::Assertions;require #{__FILE__.dump};include Test::Unit::CoreAssertions
+  separated_runner #{token_dump}, #{res_c&.fileno || 'nil'}
 }
 #{line -= __LINE__; src}
 eom
         args = args.dup
         args.insert((Hash === args.first ? 1 : 0), "-w", "--disable=gems", *$:.map {|l| "-I#{l}"})
+        args << "--debug" if RUBY_ENGINE == 'jruby' # warning: tracing (e.g. set_trace_func) will not capture all events without --debug flag
         stdout, stderr, status = EnvUtil.invoke_ruby(args, src, capture_stdout, true, **opt)
       ensure
         if res_c
@@ -302,9 +331,9 @@ def assert_separately(args, file = nil, line = nil, src, ignore_stderr: nil, **o
         raise if $!
         abort = status.coredump? || (status.signaled? && ABORT_SIGNALS.include?(status.termsig))
         assert(!abort, FailDesc[status, nil, stderr])
-        self._assertions += res[/^assertions=(\d+)/, 1].to_i
+        self._assertions += res[/^#{token_re}assertions=(\d+)/, 1].to_i
         begin
-          res = Marshal.load(res.unpack1("m"))
+          res = Marshal.load(res[/^#{token_re}<error>\n\K.*\n(?=#{token_re}<\/error>$)/m].unpack1("m"))
         rescue => marshal_error
           ignore_stderr = nil
           res = nil
@@ -401,8 +430,8 @@ def assert_raise(*exp, &b)
 
         begin
           yield
-        rescue MiniTest::Skip => e
-          return e if exp.include? MiniTest::Skip
+        rescue Test::Unit::PendedError => e
+          return e if exp.include? Test::Unit::PendedError
           raise e
         rescue Exception => e
           expected = exp.any? { |ex|
@@ -477,7 +506,7 @@ def assert_raise_with_message(exception, expected, msg = nil, &block)
         ex
       end
 
-      MINI_DIR = File.join(File.dirname(File.dirname(File.expand_path(__FILE__))), "minitest") #:nodoc:
+      TEST_DIR = File.join(__dir__, "test/unit") #:nodoc:
 
       # :call-seq:
       #   assert(test, [failure_message])
@@ -497,7 +526,7 @@ def assert(test, *msgs)
         when nil
           msgs.shift
         else
-          bt = caller.reject { |s| s.start_with?(MINI_DIR) }
+          bt = caller.reject { |s| s.start_with?(TEST_DIR) }
           raise ArgumentError, "assertion message must be String or Proc, but #{msg.class} was given.", bt
         end unless msgs.empty?
         super
@@ -520,7 +549,7 @@ def assert_respond_to(obj, (meth, *priv), msg = nil)
           return assert obj.respond_to?(meth, *priv), msg
         end
         #get rid of overcounting
-        if caller_locations(1, 1)[0].path.start_with?(MINI_DIR)
+        if caller_locations(1, 1)[0].path.start_with?(TEST_DIR)
           return if obj.respond_to?(meth)
         end
         super(obj, meth, msg)
@@ -543,17 +572,17 @@ def assert_not_respond_to(obj, (meth, *priv), msg = nil)
           return assert !obj.respond_to?(meth, *priv), msg
         end
         #get rid of overcounting
-        if caller_locations(1, 1)[0].path.start_with?(MINI_DIR)
+        if caller_locations(1, 1)[0].path.start_with?(TEST_DIR)
           return unless obj.respond_to?(meth)
         end
         refute_respond_to(obj, meth, msg)
       end
 
-      # pattern_list is an array which contains regexp and :*.
+      # pattern_list is an array which contains regexp, string and :*.
       # :* means any sequence.
       #
       # pattern_list is anchored.
-      # Use [:*, regexp, :*] for non-anchored match.
+      # Use [:*, regexp/string, :*] for non-anchored match.
       def assert_pattern_list(pattern_list, actual, message=nil)
         rest = actual
         anchored = true
@@ -562,11 +591,13 @@ def assert_pattern_list(pattern_list, actual, message=nil)
             anchored = false
           else
             if anchored
-              match = /\A#{pattern}/.match(rest)
+              match = rest.rindex(pattern, 0)
             else
-              match = pattern.match(rest)
+              match = rest.index(pattern)
             end
-            unless match
+            if match
+              post_match = $~ ? $~.post_match : rest[match+pattern.size..-1]
+            else
               msg = message(msg) {
                 expect_msg = "Expected #{mu_pp pattern}\n"
                 if /\n[^\n]/ =~ rest
@@ -583,7 +614,7 @@ def assert_pattern_list(pattern_list, actual, message=nil)
               }
               assert false, msg
             end
-            rest = match.post_match
+            rest = post_match
             anchored = true
           end
         }
@@ -610,19 +641,20 @@ def assert_warn(*args)
 
       def assert_deprecated_warning(mesg = /deprecated/)
         assert_warning(mesg) do
-          Warning[:deprecated] = true
+          Warning[:deprecated] = true if Warning.respond_to?(:[]=)
           yield
         end
       end
 
       def assert_deprecated_warn(mesg = /deprecated/)
         assert_warn(mesg) do
-          Warning[:deprecated] = true
+          Warning[:deprecated] = true if Warning.respond_to?(:[]=)
           yield
         end
       end
 
       class << (AssertFile = Struct.new(:failure_message).new)
+        include Assertions
         include CoreAssertions
         def assert_file_predicate(predicate, *args)
           if /\Anot_/ =~ predicate
@@ -654,7 +686,7 @@ def initialize
 
         def for(key)
           @count += 1
-          yield
+          yield key
         rescue Exception => e
           @failures[key] = [@count, e]
         end
@@ -708,15 +740,25 @@ def assert_join_threads(threads, message = nil)
           msg = "exceptions on #{errs.length} threads:\n" +
             errs.map {|t, err|
             "#{t.inspect}:\n" +
-              RUBY_VERSION >= "2.5.0" ? err.full_message(highlight: false, order: :top) : err.message
+              (err.respond_to?(:full_message) ? err.full_message(highlight: false, order: :top) : err.message)
           }.join("\n---\n")
           if message
             msg = "#{message}\n#{msg}"
           end
-          raise MiniTest::Assertion, msg
+          raise Test::Unit::AssertionFailedError, msg
         end
       end
 
+      def assert_all?(obj, m = nil, &blk)
+        failed = []
+        obj.each do |*a, &b|
+          unless blk.call(*a, &b)
+            failed << (a.size > 1 ? a : a[0])
+          end
+        end
+        assert(failed.empty?, message(m) {failed.pretty_inspect})
+      end
+
       def assert_all_assertions(msg = nil)
         all = AllFailures.new
         yield all
@@ -725,21 +767,67 @@ def assert_all_assertions(msg = nil)
       end
       alias all_assertions assert_all_assertions
 
-      def message(msg = nil, *args, &default) # :nodoc:
-        if Proc === msg
-          super(nil, *args) do
-            ary = [msg.call, (default.call if default)].compact.reject(&:empty?)
-            if 1 < ary.length
-              ary[0...-1] = ary[0...-1].map {|str| str.sub(/(?<!\.)\z/, '.') }
-            end
+      def assert_all_assertions_foreach(msg = nil, *keys, &block)
+        all = AllFailures.new
+        all.foreach(*keys, &block)
+      ensure
+        assert(all.pass?, message(msg) {all.message.chomp(".")})
+      end
+      alias all_assertions_foreach assert_all_assertions_foreach
+
+      %w[
+        CLOCK_THREAD_CPUTIME_ID CLOCK_PROCESS_CPUTIME_ID
+        CLOCK_MONOTONIC
+      ].find do |c|
+        if Process.const_defined?(c)
+          [c.to_sym, Process.const_get(c)].find do |clk|
             begin
-              ary.join("\n")
-            rescue Encoding::CompatibilityError
-              ary.map(&:b).join("\n")
+              Process.clock_gettime(clk)
+            rescue
+              # Constants may be defined but not implemented, e.g., mingw.
+            else
+              PERFORMANCE_CLOCK = clk
             end
           end
-        else
-          super
+        end
+      end
+
+      # Expect +seq+ to respond to +first+ and +each+ methods, e.g.,
+      # Array, Range, Enumerator::ArithmeticSequence and other
+      # Enumerable-s, and each elements should be size factors.
+      #
+      # :yield: each elements of +seq+.
+      def assert_linear_performance(seq, rehearsal: nil, pre: ->(n) {n})
+        pend "No PERFORMANCE_CLOCK found" unless defined?(PERFORMANCE_CLOCK)
+
+        # Timeout testing generally doesn't work when RJIT compilation happens.
+        rjit_enabled = defined?(RubyVM::RJIT) && RubyVM::RJIT.enabled?
+        measure = proc do |arg, message|
+          st = Process.clock_gettime(PERFORMANCE_CLOCK)
+          yield(*arg)
+          t = (Process.clock_gettime(PERFORMANCE_CLOCK) - st)
+          assert_operator 0, :<=, t, message unless rjit_enabled
+          t
+        end
+
+        first = seq.first
+        *arg = pre.call(first)
+        times = (0..(rehearsal || (2 * first))).map do
+          measure[arg, "rehearsal"].nonzero?
+        end
+        times.compact!
+        tmin, tmax = times.minmax
+        tbase = 10 ** Math.log10(tmax * ([(tmax / tmin), 2].max ** 2)).ceil
+        info = "(tmin: #{tmin}, tmax: #{tmax}, tbase: #{tbase})"
+
+        seq.each do |i|
+          next if i == first
+          t = tbase * i.fdiv(first)
+          *arg = pre.call(i)
+          message = "[#{i}]: in #{t}s #{info}"
+          Timeout.timeout(t, Timeout::Error, message) do
+            measure[arg, message]
+          end
         end
       end
 
@@ -758,6 +846,11 @@ def diff(exp, act)
         end
         q.output
       end
+
+      def new_test_token
+        token = "\e[7;1m#{$$.to_s}:#{Time.now.strftime('%s.%L')}:#{rand(0x10000).to_s(16)}:\e[m"
+        return token.dump, Regexp.quote(token)
+      end
     end
   end
 end
diff --git a/tests/lib/envutil.rb b/tests/lib/envutil.rb
index 937e1128..1ca76d17 100644
--- a/tests/lib/envutil.rb
+++ b/tests/lib/envutil.rb
@@ -15,23 +15,22 @@
 module EnvUtil
   def rubybin
     if ruby = ENV["RUBY"]
-      return ruby
-    end
-    ruby = "ruby"
-    exeext = RbConfig::CONFIG["EXEEXT"]
-    rubyexe = (ruby + exeext if exeext and !exeext.empty?)
-    3.times do
-      if File.exist? ruby and File.executable? ruby and !File.directory? ruby
-        return File.expand_path(ruby)
-      end
-      if rubyexe and File.exist? rubyexe and File.executable? rubyexe
-        return File.expand_path(rubyexe)
-      end
-      ruby = File.join("..", ruby)
-    end
-    if defined?(RbConfig.ruby)
+      ruby
+    elsif defined?(RbConfig.ruby)
       RbConfig.ruby
     else
+      ruby = "ruby"
+      exeext = RbConfig::CONFIG["EXEEXT"]
+      rubyexe = (ruby + exeext if exeext and !exeext.empty?)
+      3.times do
+        if File.exist? ruby and File.executable? ruby and !File.directory? ruby
+          return File.expand_path(ruby)
+        end
+        if rubyexe and File.exist? rubyexe and File.executable? rubyexe
+          return File.expand_path(rubyexe)
+        end
+        ruby = File.join("..", ruby)
+      end
       "ruby"
     end
   end
@@ -125,7 +124,7 @@ def terminate(pid, signal = :TERM, pgroup = nil, reprieve = 1)
 
   def invoke_ruby(args, stdin_data = "", capture_stdout = false, capture_stderr = false,
                   encoding: nil, timeout: 10, reprieve: 1, timeout_error: Timeout::Error,
-                  stdout_filter: nil, stderr_filter: nil,
+                  stdout_filter: nil, stderr_filter: nil, ios: nil,
                   signal: :TERM,
                   rubybin: EnvUtil.rubybin, precommand: nil,
                   **opt)
@@ -141,6 +140,8 @@ def invoke_ruby(args, stdin_data = "", capture_stdout = false, capture_stderr =
       out_p.set_encoding(encoding) if out_p
       err_p.set_encoding(encoding) if err_p
     end
+    ios.each {|i, o = i|opt[i] = o} if ios
+
     c = "C"
     child_env = {}
     LANG_ENVS.each {|lc| child_env[lc] = c}
@@ -150,9 +151,14 @@ def invoke_ruby(args, stdin_data = "", capture_stdout = false, capture_stderr =
     if RUBYLIB and lib = child_env["RUBYLIB"]
       child_env["RUBYLIB"] = [lib, RUBYLIB].join(File::PATH_SEPARATOR)
     end
-    child_env['ASAN_OPTIONS'] = ENV['ASAN_OPTIONS'] if ENV['ASAN_OPTIONS']
+
+    # remain env
+    %w(ASAN_OPTIONS RUBY_ON_BUG).each{|name|
+      child_env[name] = ENV[name] if !child_env.key?(name) and ENV.key?(name)
+    }
+
     args = [args] if args.kind_of?(String)
-    pid = spawn(child_env, *precommand, rubybin, *args, **opt)
+    pid = spawn(child_env, *precommand, rubybin, *args, opt)
     in_c.close
     out_c&.close
     out_c = nil
@@ -290,16 +296,24 @@ def self.diagnostic_reports(signame, pid, now)
       cmd = @ruby_install_name if "ruby-runner#{RbConfig::CONFIG["EXEEXT"]}" == cmd
       path = DIAGNOSTIC_REPORTS_PATH
       timeformat = DIAGNOSTIC_REPORTS_TIMEFORMAT
-      pat = "#{path}/#{cmd}_#{now.strftime(timeformat)}[-_]*.crash"
+      pat = "#{path}/#{cmd}_#{now.strftime(timeformat)}[-_]*.{crash,ips}"
       first = true
       30.times do
         first ? (first = false) : sleep(0.1)
         Dir.glob(pat) do |name|
           log = File.read(name) rescue next
-          if /\AProcess:\s+#{cmd} \[#{pid}\]$/ =~ log
-            File.unlink(name)
-            File.unlink("#{path}/.#{File.basename(name)}.plist") rescue nil
-            return log
+          case name
+          when /\.crash\z/
+            if /\AProcess:\s+#{cmd} \[#{pid}\]$/ =~ log
+              File.unlink(name)
+              File.unlink("#{path}/.#{File.basename(name)}.plist") rescue nil
+              return log
+            end
+          when /\.ips\z/
+            if /^ *"pid" *: *#{pid},/ =~ log
+              File.unlink(name)
+              return log
+            end
           end
         end
       end