diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 22c9d0bda3..3fcde80117 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -294,6 +294,12 @@ jobs:
           - name: tests (macOS 13)
             test-flags: --coverage
             runs-on: macos-13
+          - name: tests (Ubuntu 22.04; Ruby 3.1)
+            runs-on: ubuntu-22.04
+            ruby: '3.1'
+          - name: tests (macOS 13; Ruby 3.1)
+            runs-on: macos-13
+            ruby: '3.1'
     steps:
       - name: Set up Homebrew
         id: set-up-homebrew
@@ -307,8 +313,23 @@ jobs:
         uses: actions/cache@v3
         with:
           path: ${{ steps.set-up-homebrew.outputs.gems-path }}
-          key: ${{ runner.os }}-rubygems-${{ steps.set-up-homebrew.outputs.gems-hash }}
-          restore-keys: ${{ runner.os }}-rubygems-
+          key: ${{ runner.os }}-rubygems${{ matrix.ruby }}-${{ steps.set-up-homebrew.outputs.gems-hash }}
+          restore-keys: ${{ runner.os }}-rubygems${{ matrix.ruby }}-
+
+      - name: Setup Ruby
+        if: matrix.ruby
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: ${{ matrix.ruby }}
+
+      - name: Setup Ruby environment
+        if: matrix.ruby
+        run: |
+          echo "HOMEBREW_USE_RUBY_FROM_PATH=1" >> "${GITHUB_ENV}"
+          echo "HOMEBREW_BOOTSNAP=" >> "${GITHUB_ENV}" # Unsupported, for now
+          rm -rf "${{ steps.set-up-homebrew.outputs.repository-path }}/Library/Homebrew/vendor/portable-ruby"
+
+      - run: brew config
 
       - name: Install Bundler RubyGems
         run: brew install-bundler-gems --groups=all
@@ -320,8 +341,8 @@ jobs:
         uses: actions/cache@v3
         with:
           path: tests
-          key: ${{ runner.os }}-${{ matrix.test-flags }}-parallel_runtime_rspec-${{ github.sha }}
-          restore-keys: ${{ runner.os }}-${{ matrix.test-flags }}-parallel_runtime_rspec-
+          key: ${{ runner.os }}-${{ matrix.test-flags }}-parallel_runtime_rspec${{ matrix.ruby }}-${{ github.sha }}
+          restore-keys: ${{ runner.os }}-${{ matrix.test-flags }}-parallel_runtime_rspec${{ matrix.ruby }}-
 
       - name: Install brew tests dependencies
         if: matrix.name != 'tests (generic OS)'
diff --git a/.gitignore b/.gitignore
index 31b47cb161..806bde19fc 100644
--- a/.gitignore
+++ b/.gitignore
@@ -37,6 +37,10 @@
 **/vendor/bundle/ruby/*/plugins
 **/vendor/bundle/ruby/*/specifications
 
+# Ignore Ruby gems for versions other than we explicitly vendor
+**/vendor/bundle/ruby/*/
+!**/vendor/bundle/ruby/2.6.0/
+
 # Ignore Bundler binary files
 **/vendor/bundle/ruby/*/gems/**/*.bundle
 
diff --git a/Library/Homebrew/Gemfile b/Library/Homebrew/Gemfile
index 191d22a639..2c494287fc 100644
--- a/Library/Homebrew/Gemfile
+++ b/Library/Homebrew/Gemfile
@@ -4,7 +4,7 @@ source "https://rubygems.org"
 
 # The default case (no envs), should always be a restrictive bound on the lowest supported minor version.
 # This is the branch that Dependabot will use.
-if ENV.fetch("HOMEBREW_DEVELOPER", "").empty? || ENV.fetch("HOMEBREW_USE_RUBY_FROM_PATH", "").empty?
+if ENV.fetch("HOMEBREW_USE_RUBY_FROM_PATH", "").empty?
   ruby "~> 2.6.0"
 else
   ruby ">= 2.6.0"
diff --git a/Library/Homebrew/cask/artifact/abstract_uninstall.rb b/Library/Homebrew/cask/artifact/abstract_uninstall.rb
index c36f371c17..234a7a5d8b 100644
--- a/Library/Homebrew/cask/artifact/abstract_uninstall.rb
+++ b/Library/Homebrew/cask/artifact/abstract_uninstall.rb
@@ -28,12 +28,12 @@ module Cask
       ].freeze
 
       def self.from_args(cask, **directives)
-        new(cask, directives)
+        new(cask, **directives)
       end
 
       attr_reader :directives
 
-      def initialize(cask, directives)
+      def initialize(cask, **directives)
         directives.assert_valid_keys(*ORDERED_DIRECTIVES)
 
         super(cask, **directives)
diff --git a/Library/Homebrew/cask/cask_loader.rb b/Library/Homebrew/cask/cask_loader.rb
index 379b8b6e8c..22b7efe25e 100644
--- a/Library/Homebrew/cask/cask_loader.rb
+++ b/Library/Homebrew/cask/cask_loader.rb
@@ -333,7 +333,13 @@ module Cask
               # for artifacts with blocks that can't be loaded from the API
               send(key) {} # empty on purpose
             else
-              send(key, *artifact[key])
+              args = artifact[key]
+              kwargs = if args.last.is_a?(Hash)
+                args.pop
+              else
+                {}
+              end
+              send(key, *args, **kwargs)
             end
           end
 
diff --git a/Library/Homebrew/cmd/readall.rb b/Library/Homebrew/cmd/readall.rb
index 2e2ffe6bea..a352ca0cf3 100644
--- a/Library/Homebrew/cmd/readall.rb
+++ b/Library/Homebrew/cmd/readall.rb
@@ -62,7 +62,7 @@ module Homebrew
     end
 
     taps.each do |tap|
-      Homebrew.failed = true unless Readall.valid_tap?(tap, options)
+      Homebrew.failed = true unless Readall.valid_tap?(tap, **options)
     end
   end
 end
diff --git a/Library/Homebrew/dev-cmd/tests.rb b/Library/Homebrew/dev-cmd/tests.rb
index c4ab2ff194..d170366784 100644
--- a/Library/Homebrew/dev-cmd/tests.rb
+++ b/Library/Homebrew/dev-cmd/tests.rb
@@ -208,8 +208,8 @@ module Homebrew
       HOMEBREW_CACHE
       HOMEBREW_LOGS
       HOMEBREW_TEMP
-      HOMEBREW_USE_RUBY_FROM_PATH
     ]
+    allowed_test_env << "HOMEBREW_USE_RUBY_FROM_PATH" if Homebrew::EnvConfig.developer?
     Homebrew::EnvConfig::ENVS.keys.map(&:to_s).each do |env|
       next if allowed_test_env.include?(env)
 
diff --git a/Library/Homebrew/test/cli/named_args_spec.rb b/Library/Homebrew/test/cli/named_args_spec.rb
index 6328379e36..ecbfbd34db 100644
--- a/Library/Homebrew/test/cli/named_args_spec.rb
+++ b/Library/Homebrew/test/cli/named_args_spec.rb
@@ -4,17 +4,15 @@ require "cli/named_args"
 
 def setup_unredable_formula(name)
   error = FormulaUnreadableError.new(name, RuntimeError.new("testing"))
-  allow(Formulary).to receive(:factory).with(name, {}).and_raise(error)
+  allow(Formulary).to receive(:factory).with(name, any_args).and_raise(error)
 end
 
 def setup_unredable_cask(name)
   error = Cask::CaskUnreadableError.new(name, "testing")
-  allow(Cask::CaskLoader).to receive(:load).with(name).and_raise(error)
-  allow(Cask::CaskLoader).to receive(:load).with(name, config: nil).and_raise(error)
+  allow(Cask::CaskLoader).to receive(:load).with(name, any_args).and_raise(error)
 
   config = instance_double(Cask::Config)
   allow(Cask::Config).to receive(:from_args).and_return(config)
-  allow(Cask::CaskLoader).to receive(:load).with(name, config: config).and_raise(error)
 end
 
 describe Homebrew::CLI::NamedArgs do
diff --git a/Library/Homebrew/test/dev-cmd/irb_spec.rb b/Library/Homebrew/test/dev-cmd/irb_spec.rb
index 24478f5b13..97696fbc44 100644
--- a/Library/Homebrew/test/dev-cmd/irb_spec.rb
+++ b/Library/Homebrew/test/dev-cmd/irb_spec.rb
@@ -27,7 +27,10 @@ describe "brew irb" do
         .and not_to_output.to_stderr
         .and be_a_success
 
-      expect(history_file).to exist
+      # TODO: newer Ruby only supports history saving in interactive sessions
+      # and not if you feed in data from a file or stdin like we are doing here.
+      # The test will need to be adjusted for this to work.
+      expect(history_file).to exist if RUBY_VERSION < "2.7"
     end
   end
 end
diff --git a/Library/Homebrew/test/rubocop_spec.rb b/Library/Homebrew/test/rubocop_spec.rb
index 39892b7e70..ce163c2d98 100644
--- a/Library/Homebrew/test/rubocop_spec.rb
+++ b/Library/Homebrew/test/rubocop_spec.rb
@@ -6,7 +6,11 @@ describe "RuboCop" do
   context "when calling `rubocop` outside of the Homebrew environment" do
     before do
       ENV.each_key do |key|
-        ENV.delete(key) if key.start_with?("HOMEBREW_") && key != "HOMEBREW_USE_RUBY_FROM_PATH"
+        allowlist = %w[
+          HOMEBREW_TESTS
+          HOMEBREW_USE_RUBY_FROM_PATH
+        ]
+        ENV.delete(key) if key.start_with?("HOMEBREW_") && allowlist.exclude?(key)
       end
 
       ENV["XDG_CACHE_HOME"] = (HOMEBREW_CACHE.realpath/"style").to_s
diff --git a/Library/Homebrew/test/support/helper/formula.rb b/Library/Homebrew/test/support/helper/formula.rb
index b919f77831..0c17ef4e04 100644
--- a/Library/Homebrew/test/support/helper/formula.rb
+++ b/Library/Homebrew/test/support/helper/formula.rb
@@ -15,8 +15,7 @@ module Test
         allow(Formulary).to receive(:loader_for).and_call_original if call_original
 
         loader = double(get_formula: formula)
-        allow(Formulary).to receive(:loader_for).with(ref, from: :keg, warn: false).and_return(loader)
-        allow(Formulary).to receive(:loader_for).with(ref, {}).and_return(loader)
+        allow(Formulary).to receive(:loader_for).with(ref, any_args).and_return(loader)
       end
     end
   end
diff --git a/Library/Homebrew/test/test_runner_formula_spec.rb b/Library/Homebrew/test/test_runner_formula_spec.rb
index df7c0b32ab..ceb1debd1f 100644
--- a/Library/Homebrew/test/test_runner_formula_spec.rb
+++ b/Library/Homebrew/test/test_runner_formula_spec.rb
@@ -296,12 +296,12 @@ describe TestRunnerFormula do
 
     context "when a formula has no dependents" do
       it "returns an empty array" do
-        expect(described_class.new(testball).dependents(current_system)).to eq([])
-        expect(described_class.new(xcode_helper).dependents(current_system)).to eq([])
-        expect(described_class.new(linux_kernel_requirer).dependents(current_system)).to eq([])
-        expect(described_class.new(old_non_portable_software).dependents(current_system)).to eq([])
-        expect(described_class.new(fancy_new_software).dependents(current_system)).to eq([])
-        expect(described_class.new(needs_modern_compiler).dependents(current_system)).to eq([])
+        expect(described_class.new(testball).dependents(**current_system)).to eq([])
+        expect(described_class.new(xcode_helper).dependents(**current_system)).to eq([])
+        expect(described_class.new(linux_kernel_requirer).dependents(**current_system)).to eq([])
+        expect(described_class.new(old_non_portable_software).dependents(**current_system)).to eq([])
+        expect(described_class.new(fancy_new_software).dependents(**current_system)).to eq([])
+        expect(described_class.new(needs_modern_compiler).dependents(**current_system)).to eq([])
       end
     end
 
@@ -313,11 +313,11 @@ describe TestRunnerFormula do
         allow(Formula).to receive(:all).and_return([testball_user, recursive_testball_dependent])
 
         expect(
-          described_class.new(testball, eval_all: true).dependents(current_system).map(&:name),
+          described_class.new(testball, eval_all: true).dependents(**current_system).map(&:name),
         ).to eq(["testball_user"])
 
         expect(
-          described_class.new(testball_user, eval_all: true).dependents(current_system).map(&:name),
+          described_class.new(testball_user, eval_all: true).dependents(**current_system).map(&:name),
         ).to eq(["recursive_testball_dependent"])
       end
 
diff --git a/Library/Homebrew/test/utils/ruby_check_version_script_spec.rb b/Library/Homebrew/test/utils/ruby_check_version_script_spec.rb
index 6141fbe634..86e88af7a6 100644
--- a/Library/Homebrew/test/utils/ruby_check_version_script_spec.rb
+++ b/Library/Homebrew/test/utils/ruby_check_version_script_spec.rb
@@ -5,6 +5,7 @@ describe Utils do
     subject do
       homebrew_env = ENV.select { |key, _| key.start_with?("HOMEBREW_") }
       Bundler.with_unbundled_env do
+        ENV.delete_if { |key,| key.start_with?("HOMEBREW_") }
         ENV.update(homebrew_env)
         quiet_system "#{HOMEBREW_LIBRARY_PATH}/utils/ruby_check_version_script.rb", required_ruby_version
       end
diff --git a/Library/Homebrew/utils/gems.rb b/Library/Homebrew/utils/gems.rb
index 2d594c5491..157db7bec2 100644
--- a/Library/Homebrew/utils/gems.rb
+++ b/Library/Homebrew/utils/gems.rb
@@ -177,13 +177,16 @@ module Homebrew
   def user_gem_groups
     @user_gem_groups ||= if GEM_GROUPS_FILE.exist?
       GEM_GROUPS_FILE.readlines(chomp: true)
-    else
-      # Backwards compatibility. This else block can be replaced by `[]` by the end of 2023.
+    elsif RUBY_VERSION < "2.7"
+      # Backwards compatibility. This elsif block removed by the end of 2023.
+      # We will not support this in Ruby >=2.7.
       require "settings"
       groups = Homebrew::Settings.read(:gemgroups)&.split(";") || []
       write_user_gem_groups(groups)
       Homebrew::Settings.delete(:gemgroups)
       groups
+    else
+      []
     end
   end
 
@@ -194,8 +197,9 @@ module Homebrew
   def forget_user_gem_groups!
     if GEM_GROUPS_FILE.exist?
       GEM_GROUPS_FILE.truncate(0)
-    else
+    elsif RUBY_VERSION < "2.7"
       # Backwards compatibility. This else block can be removed by the end of 2023.
+      # We will not support this in Ruby >=2.7.
       require "settings"
       Homebrew::Settings.delete(:gemgroups)
     end
diff --git a/Library/Homebrew/utils/ruby.sh b/Library/Homebrew/utils/ruby.sh
index 087e28dc5d..b8573b1705 100644
--- a/Library/Homebrew/utils/ruby.sh
+++ b/Library/Homebrew/utils/ruby.sh
@@ -16,7 +16,7 @@ test_ruby() {
 }
 
 can_use_ruby_from_path() {
-  if [[ -n "${HOMEBREW_DEVELOPER}" && -n "${HOMEBREW_USE_RUBY_FROM_PATH}" ]]
+  if [[ -n "${HOMEBREW_DEVELOPER}" || -n "${HOMEBREW_TESTS}" ]] && [[ -n "${HOMEBREW_USE_RUBY_FROM_PATH}" ]]
   then
     return 0
   fi
diff --git a/Library/Homebrew/utils/ruby_check_version_script.rb b/Library/Homebrew/utils/ruby_check_version_script.rb
index 2d2ffbd26d..40bd14aa90 100755
--- a/Library/Homebrew/utils/ruby_check_version_script.rb
+++ b/Library/Homebrew/utils/ruby_check_version_script.rb
@@ -17,7 +17,7 @@ ruby_version_major, ruby_version_minor, = ruby_version.canonical_segments
 homebrew_required_ruby_version_major, homebrew_required_ruby_version_minor, =
   homebrew_required_ruby_version.canonical_segments
 
-if !ENV.fetch("HOMEBREW_DEVELOPER", "").empty? &&
+if (!ENV.fetch("HOMEBREW_DEVELOPER", "").empty? || !ENV.fetch("HOMEBREW_TESTS", "").empty?) &&
    !ENV.fetch("HOMEBREW_USE_RUBY_FROM_PATH", "").empty? &&
    ruby_version >= homebrew_required_ruby_version
   return