diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 532e79a8..ceb9d506 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -8,7 +8,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ruby: [2.7, '3.0', '3.1', '3.2']
+        ruby: ['3.1', '3.2', '3.3', '3.4']
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v3
diff --git a/.github/workflows/ci_jruby.yml b/.github/workflows/ci_jruby.yml
deleted file mode 100644
index aead15d9..00000000
--- a/.github/workflows/ci_jruby.yml
+++ /dev/null
@@ -1,19 +0,0 @@
-## This file is managed by Terraform.
-## Do not modify this file directly, as it may be overwritten.
-## Please open an issue instead.
-name: CI JRuby
-on: [push, pull_request]
-jobs:
-  test:
-    strategy:
-      fail-fast: false
-      matrix:
-        ruby: [jruby, jruby-head]
-    runs-on: ubuntu-latest
-    steps:
-    - uses: actions/checkout@v3
-    - uses: ruby/setup-ruby@v1
-      with:
-        ruby-version: ${{ matrix.ruby }}
-        bundler-cache: true
-    - run: bundle exec rake
diff --git a/.github/workflows/ci_legacy.yml b/.github/workflows/ci_legacy.yml
deleted file mode 100644
index f30c3314..00000000
--- a/.github/workflows/ci_legacy.yml
+++ /dev/null
@@ -1,19 +0,0 @@
-## This file is managed by Terraform.
-## Do not modify this file directly, as it may be overwritten.
-## Please open an issue instead.
-name: CI with EOL ruby versions
-on: [push, pull_request]
-jobs:
-  test:
-    strategy:
-      fail-fast: false
-      matrix:
-        ruby: [2.5, 2.6]
-    runs-on: ubuntu-latest
-    steps:
-    - uses: actions/checkout@v3
-    - uses: ruby/setup-ruby@v1
-      with:
-        ruby-version: ${{ matrix.ruby }}
-        bundler-cache: true
-    - run: bundle exec rake
diff --git a/.github/workflows/ci_truffleruby.yml b/.github/workflows/ci_truffleruby.yml
deleted file mode 100644
index d4bad045..00000000
--- a/.github/workflows/ci_truffleruby.yml
+++ /dev/null
@@ -1,19 +0,0 @@
-## This file is managed by Terraform.
-## Do not modify this file directly, as it may be overwritten.
-## Please open an issue instead.
-name: CI TruffleRuby
-on: [push, pull_request]
-jobs:
-  test:
-    strategy:
-      fail-fast: false
-      matrix:
-        ruby: [truffleruby, truffleruby-head]
-    runs-on: ubuntu-latest
-    steps:
-    - uses: actions/checkout@v3
-    - uses: ruby/setup-ruby@v1
-      with:
-        ruby-version: ${{ matrix.ruby }}
-        bundler-cache: true
-    - run: bundle exec rake
diff --git a/Gemfile b/Gemfile
index da67af7d..bd9097d9 100644
--- a/Gemfile
+++ b/Gemfile
@@ -6,6 +6,8 @@ group :test do
   gem "minitest-line"
   gem "multi_json", require: false
   gem "nokogiri", require: false
+  gem "mutex_m"
+  gem "diff-lcs"
 end
 gem 'pry-byebug'
 
diff --git a/representable.gemspec b/representable.gemspec
index 74cff19d..c90c6fc6 100644
--- a/representable.gemspec
+++ b/representable.gemspec
@@ -27,7 +27,7 @@ Gem::Specification.new do |spec|
 
   spec.add_development_dependency "rake"
   spec.add_development_dependency "test_xml", ">= 0.1.6"
-  spec.add_development_dependency "minitest"
+  spec.add_development_dependency "minitest", "~> 5.9.0"
   spec.add_development_dependency "dry-types"
   spec.add_development_dependency "ruby-prof" if RUBY_ENGINE == "ruby" # mri
 end
diff --git a/test/as_test.rb b/test/as_test.rb
index 1040d19a..401e5bb0 100644
--- a/test/as_test.rb
+++ b/test/as_test.rb
@@ -32,8 +32,8 @@ class AsTest < MiniTest::Spec
         property :name, :as => ->(options) { options[:user_options].inspect }
       end
 
-      it { render(song, user_options: {volume: 1}).must_equal_document({"{:volume=>1}" => "Revolution"}) }
-      it { _(parse(song, {"{:volume=>1}" => "Wie Es Geht"}, user_options: {volume: 1}).name).must_equal "Wie Es Geht" }
+      it { render(song, user_options: {volume: 1}).must_equal_document({{volume: 1}.inspect => "Revolution"}) }
+      it { _(parse(song, {{volume: 1}.inspect => "Wie Es Geht"}, user_options: {volume: 1}).name).must_equal "Wie Es Geht" }
     end
   end
 end
diff --git a/test/cached_test.rb b/test/cached_test.rb
index 569da5f8..6297d9c5 100644
--- a/test/cached_test.rb
+++ b/test/cached_test.rb
@@ -21,6 +21,8 @@ def self.profile(&block)
         printer.printProfile(print_stream)
         output_stream.toString
     end
+  rescue LoadError
+    false
   end
 end
 
@@ -51,6 +53,10 @@ class AlbumRepresenter < Representable::Decorator
     collection :songs, decorator: SongRepresenter, class: Model::Song
   end
 
+  before do
+    @profiler_available = Profiler.profile {}
+  end
+
   describe "serialization" do
     let(:album_hash) do
       {
@@ -68,12 +74,13 @@ class AlbumRepresenter < Representable::Decorator
       # album2 = Model::Album.new("Louder And Even More Dangerous", [song2, song])
 
       # makes sure options are passed correctly.
-      _(representer.to_hash(user_options: {volume: 9})).must_equal(
+      options = {volume: 9}
+      _(representer.to_hash(user_options: options)).must_equal(
         {
           "name"  => "Live And Dangerous",
           "songs" => [
-            {"title"=>"Jailbreak:{:volume=>9}"}, {"title"=>"Southbound:{:volume=>9}"},
-            {"title"=>"Emerald:{:volume=>9}"}
+            {"title"=>"Jailbreak:#{options}"}, {"title"=>"Southbound:#{options}"},
+            {"title"=>"Emerald:#{options}"}
           ]
         }
       ) # called in Deserializer/Serializer
@@ -87,6 +94,8 @@ class AlbumRepresenter < Representable::Decorator
 
     # profiling
     it do
+      skip "ruby_prof not available" unless @profiler_available
+
       representer.to_hash
 
       data = Profiler.profile { representer.to_hash }
@@ -141,6 +150,8 @@ class AlbumRepresenter < Representable::Decorator
     end
 
     it "xxx" do
+      skip "ruby_prof not available" unless @profiler_available
+
       representer = AlbumRepresenter.new(Model::Album.new)
       representer.from_hash(album_hash)
 
diff --git a/test/definition_test.rb b/test/definition_test.rb
index d858b36e..ecede345 100644
--- a/test/definition_test.rb
+++ b/test/definition_test.rb
@@ -90,8 +90,9 @@ class DefinitionTest < MiniTest::Spec
 
   # #inspect
   describe "#inspect" do
+    options = {name: "songs", parse_filter: [], render_filter: []}
     it {
-      _(Definition.new(:songs).inspect).must_equal "#<Representable::Definition ==>songs @options={:name=>\"songs\", :parse_filter=>[], :render_filter=>[]}>"
+      _(Definition.new(:songs).inspect).must_equal "#<Representable::Definition ==>songs @options=#{options}>"
     }
   end
 
diff --git a/test/filter_test.rb b/test/filter_test.rb
index ab4bfb39..29e4144c 100644
--- a/test/filter_test.rb
+++ b/test/filter_test.rb
@@ -20,12 +20,14 @@ class FilterTest < MiniTest::Spec
 
   # gets doc and options.
   it {
-    song = OpenStruct.new.extend(representer).from_hash("title" => "VULCAN EARS", "track" => "Nine")
+    input = {"title" => "VULCAN EARS", "track" => "Nine"}
+    song = OpenStruct.new.extend(representer).from_hash(input)
     _(song.title).must_equal "VULCAN EARS"
-    _(song.track).must_equal "nine,{\"title\"=>\"VULCAN EARS\", \"track\"=>\"Nine\"}"
+    _(song.track).must_equal "nine,#{input}"
   }
 
   it {
+    val = {"title" => "vulcan ears"}
     _(
       OpenStruct.new(
         "title" => "vulcan ears",
@@ -33,7 +35,7 @@ class FilterTest < MiniTest::Spec
       ).extend(representer).to_hash
     ).must_equal({
                    "title" => "vulcan ears",
-                   "track" => "NINE,{\"title\"=>\"vulcan ears\"},{}"
+                   "track" => "NINE,#{val},{}"
                  })
   }
 
diff --git a/test/serialize_deserialize_test.rb b/test/serialize_deserialize_test.rb
index d82caf0b..5d4d5786 100644
--- a/test/serialize_deserialize_test.rb
+++ b/test/serialize_deserialize_test.rb
@@ -13,7 +13,7 @@ class SerializeDeserializeTest < BaseTest
                }
     end
 
-    it { _(subject.from_hash({"song" => Object}, user_options: {volume: 9}).song).must_equal "OBJECT Object {:volume=>9}" }
+    it { _(subject.from_hash({"song" => Object}, user_options: {volume: 9}).song).must_equal "OBJECT Object #{{volume: 9}}" }
   end
 
   describe "serialize" do
@@ -28,6 +28,6 @@ class SerializeDeserializeTest < BaseTest
 
     before { subject.song = "Arrested In Shanghai" }
 
-    it { _(subject.to_hash(user_options: {volume: 9})).must_equal({"song"=>"Arrested In Shanghai {:volume=>9}"}) }
+    it { _(subject.to_hash(user_options: {volume: 9})).must_equal({"song"=>"Arrested In Shanghai #{{volume: 9}}"}) }
   end
 end