Added json gem 3.x support while keeping the 2.x wire format.

.github/workflows/ruby.yml

@@ -1,5 +1,8 @@
 # Build and test the RubyTree library.
 #
+# The matrix runs the suite against both the json gem 2.x and 3.x, selected
+# through the Gemfile variants in the gemfiles/ directory.
+#
 # This runs as a Github Action.
 
 name: Build and Test
@@ -8,11 +11,15 @@ permissions:
   contents: read
 jobs:
   test:
+    name: Ruby ${{ matrix.ruby }} / json ${{ matrix.json }}
     strategy:
       fail-fast: false
       matrix:
         ruby: ["2.7", "3.0", "3.1", "3.2", "3.3"]
+        json: ["2", "3"]
     runs-on: ubuntu-latest
+    env:
+      BUNDLE_GEMFILE: ${{ github.workspace }}/gemfiles/json_${{ matrix.json }}.gemfile
     steps:
       - uses: actions/checkout@v7
       - uses: ruby/setup-ruby@v1

.gitignore

@@ -11,3 +11,4 @@ tmp/
 vendor/
 .idea/
 Gemfile.lock
+gemfiles/*.lock

.rubocop.yml

@@ -3,6 +3,11 @@
 # Inherit from the working file.
 inherit_from: .rubocop_todo.yml
 
+# Load the rake and rspec extensions as plugins.
+plugins:
+  - rubocop-rake
+  - rubocop-rspec
+
 AllCops:
   NewCops: enable
   TargetRubyVersion: 2.7

.rubocop_todo.yml

@@ -1,45 +1,121 @@
 # This configuration was generated by
 # `rubocop --auto-gen-config`
-# on 2022-06-20 06:06:47 UTC using RuboCop version 1.24.0.
+# on 2026-10-07 08:17:12 UTC using RuboCop version 1.91.0.
 # The point is for the user to remove these configuration records
 # one by one as the offenses are removed from the code base.
 # Note that changes in the inspected code, or installation of new
 # versions of RuboCop, may require this file to be generated again.
 
-# Offense count: 47
-# Configuration parameters: IgnoredMethods, CountRepeatedAttributes.
+# Offense count: 15
+# Configuration parameters: EnforcedStyle, AllowedGems.
+# SupportedStyles: Gemfile, gems.rb, gemspec
+Gemspec/DevelopmentDependencies:
+  Exclude:
+    - 'rubytree.gemspec'
+
+# Offense count: 1
+# This cop supports safe autocorrection (--autocorrect).
+# Configuration parameters: EnforcedStyle.
+# SupportedStyles: leading, trailing
+Layout/LineContinuationLeadingSpace:
+  Exclude:
+    - 'lib/tree.rb'
+
+# Offense count: 13
+# This cop supports safe autocorrection (--autocorrect).
+# Configuration parameters: EnforcedStyle.
+# SupportedStyles: space, no_space
+Layout/LineContinuationSpacing:
+  Exclude:
+    - 'lib/tree.rb'
+    - 'lib/tree/binarytree.rb'
+    - 'lib/tree/utils/hash_converter.rb'
+
+# Offense count: 50
+# Configuration parameters: AllowedMethods, AllowedPatterns, CountRepeatedAttributes.
 Metrics/AbcSize:
   Max: 97
 
 # Offense count: 2
-# Configuration parameters: CountComments, CountAsOne, ExcludedMethods, IgnoredMethods.
-# IgnoredMethods: refine
+# Configuration parameters: CountComments, CountAsOne, AllowedMethods, AllowedPatterns, inherit_mode.
+# AllowedMethods: refine
 Metrics/BlockLength:
-  Max: 119
+  Max: 34
 
 # Offense count: 3
 # Configuration parameters: CountComments, CountAsOne.
 Metrics/ClassLength:
-  Max: 1066
+  Max: 1109
 
-# Offense count: 2
-# Configuration parameters: IgnoredMethods.
+# Offense count: 4
+# Configuration parameters: AllowedMethods, AllowedPatterns.
 Metrics/CyclomaticComplexity:
-  Max: 8
+  Max: 10
 
-# Offense count: 47
-# Configuration parameters: CountComments, CountAsOne, ExcludedMethods, IgnoredMethods.
+# Offense count: 51
+# Configuration parameters: CountComments, CountAsOne, AllowedMethods, AllowedPatterns.
 Metrics/MethodLength:
   Max: 45
 
-# Offense count: 1
-# Configuration parameters: IgnoredMethods.
+# Offense count: 3
+# Configuration parameters: AllowedMethods, AllowedPatterns.
 Metrics/PerceivedComplexity:
-  Max: 9
+  Max: 11
+
+# Offense count: 1
+# Configuration parameters: EnforcedStyle, AllowedPatterns, ForbiddenIdentifiers, ForbiddenPatterns.
+# SupportedStyles: snake_case, camelCase
+# ForbiddenIdentifiers: __id__, __send__
+Naming/MethodName:
+  Exclude:
+    - 'test/test_tree.rb'
+
+# Offense count: 4
+# Configuration parameters: Max, AllowedIdentifiers, AllowedPatterns.
+RSpec/IndexedLet:
+  Exclude:
+    - 'spec/tree_spec.rb'
+
+# Offense count: 1
+RSpec/LeakyLocalVariable:
+  Exclude:
+    - 'spec/tree_spec.rb'
+
+# Offense count: 1
+# This cop supports unsafe autocorrection (--autocorrect-all).
+RSpec/Output:
+  Exclude:
+    - 'spec/spec_helper.rb'
+
+# Offense count: 1
+# This cop supports safe autocorrection (--autocorrect).
+RSpec/RedundantPredicateMatcher:
+  Exclude:
+    - 'spec/tree_spec.rb'
 
 # Offense count: 5
 Security/MarshalLoad:
   Exclude:
     - 'lib/tree.rb'
     - 'spec/tree_spec.rb'
     - 'test/test_tree.rb'
+
+# Offense count: 1
+# This cop supports unsafe autocorrection (--autocorrect-all).
+Style/MapIntoArray:
+  Exclude:
+    - 'test/test_tree.rb'
+
+# Offense count: 1
+# This cop supports safe autocorrection (--autocorrect).
+# Configuration parameters: AllowedMethods.
+# AllowedMethods: infinite?, nonzero?
+Style/RedundantCondition:
+  Exclude:
+    - 'lib/tree.rb'
+
+# Offense count: 2
+# This cop supports safe autocorrection (--autocorrect).
+Style/SuperArguments:
+  Exclude:
+    - 'lib/tree/binarytree.rb'

Gemfile.lock

@@ -2,12 +2,12 @@ PATH
   remote: .
   specs:
     rubytree (2.2.2)
-      json (~> 2.0, >= 2.21.2)
+      json (>= 2.21.2, < 4)
 
 GEM
   remote: https://rubygems.org/
   specs:
-    ast (2.4.2)
+    ast (2.4.3)
     awesome_bot (1.20.0)
       parallel (= 1.20.1)
     bundler-audit (0.9.3)
@@ -19,12 +19,13 @@ GEM
     date (3.4.1)
     diff-lcs (1.5.1)
     docile (1.4.1)
-    json (2.21.2)
+    json (3.0.2)
     kramdown (2.5.2)
       rexml (>= 3.4.4)
     kramdown-parser-gfm (1.1.0)
       kramdown (~> 2.0)
-    language_server-protocol (3.17.0.3)
+    language_server-protocol (3.17.0.6)
+    lint_roller (1.1.0)
     mdl (0.14.0)
       kramdown (~> 2.3)
       kramdown-parser-gfm (~> 1.1)
@@ -37,10 +38,11 @@ GEM
     mixlib-shellout (3.3.8)
       chef-utils
     parallel (1.20.1)
-    parser (3.3.6.0)
+    parser (3.3.12.0)
       ast (~> 2.4.1)
       racc
     power_assert (2.0.4)
+    prism (1.9.0)
     psych (5.2.2)
       date
       stringio
@@ -49,7 +51,7 @@ GEM
     rake (13.2.1)
     rdoc (6.10.0)
       psych (>= 4.0.0)
-    regexp_parser (2.9.3)
+    regexp_parser (2.13.1)
     rexml (3.4.4)
     rspec (3.13.0)
       rspec-core (~> 3.13.0)
@@ -67,22 +69,27 @@ GEM
     rtags (0.97)
     rtagstask (0.0.4)
       rtags (> 0.0.0)
-    rubocop (1.69.2)
-      json (~> 2.3)
-      language_server-protocol (>= 3.17.0)
-      parallel (~> 1.10)
+    rubocop (1.91.0)
+      json (>= 2.3)
+      language_server-protocol (~> 3.17.0.2)
+      lint_roller (~> 1.1.0)
+      parallel (>= 1.10)
       parser (>= 3.3.0.2)
       rainbow (>= 2.2.2, < 4.0)
       regexp_parser (>= 2.9.3, < 3.0)
-      rubocop-ast (>= 1.36.2, < 2.0)
+      rubocop-ast (>= 1.49.0, < 2.0)
       ruby-progressbar (~> 1.7)
       unicode-display_width (>= 2.4.0, < 4.0)
-    rubocop-ast (1.37.0)
-      parser (>= 3.3.1.0)
-    rubocop-rake (0.6.0)
-      rubocop (~> 1.0)
-    rubocop-rspec (3.3.0)
-      rubocop (~> 1.61)
+    rubocop-ast (1.50.0)
+      parser (>= 3.3.7.2)
+      prism (~> 1.7)
+    rubocop-rake (0.7.1)
+      lint_roller (~> 1.1)
+      rubocop (>= 1.72.1)
+    rubocop-rspec (3.10.2)
+      lint_roller (~> 1.1)
+      regexp_parser (>= 2.0)
+      rubocop (~> 1.86, >= 1.86.2)
     ruby-progressbar (1.13.0)
     simplecov (0.22.0)
       docile (~> 1.1)
@@ -96,24 +103,23 @@ GEM
       power_assert
     thor (1.5.0)
     tomlrb (2.0.4)
-    unicode-display_width (3.1.2)
-      unicode-emoji (~> 4.0, >= 4.0.4)
-    unicode-emoji (4.0.4)
+    unicode-display_width (3.3.0)
+      unicode-emoji (~> 4.3)
+    unicode-emoji (4.3.0)
     yard (0.9.44)
 
 PLATFORMS
   ruby
 
 DEPENDENCIES
   awesome_bot (~> 1.20)
-  bundler (~> 2.3)
   bundler-audit (~> 0.9)
   mdl (~> 0.14)
   rake (~> 13.2)
   rdoc (~> 6.10)
   rspec (~> 3.0, >= 3.13)
   rtagstask (~> 0.0.4)
-  rubocop (~> 1.69)
+  rubocop (~> 1.90)
   rubocop-rake (~> 0.6)
   rubocop-rspec (~> 3.3)
   rubytree!

README.md

@@ -123,7 +123,7 @@ This example can also be found at
 
 * Run-time Dependencies:
 
-    * [JSON][] for converting to/from the JSON format
+    * [JSON][] (2.x or 3.x) for converting to/from the JSON format
 
 
 * Development dependencies (not required for installing the gem):

Rakefile

@@ -194,8 +194,6 @@ require 'rubocop/rake_task'
 
 RuboCop::RakeTask.new(:rubocop) do |t|
   t.options = ['--display-cop-names']
-  t.requires << 'rubocop-rake'
-  t.requires << 'rubocop-rspec'
 end
 
 # ................................ Gem metadata

gemfiles/json_2.gemfile

@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+# Variant of the main Gemfile which pins the json gem to its 2.x line. The
+# test matrix selects it through the BUNDLE_GEMFILE environment variable.
+eval_gemfile File.expand_path('../Gemfile', __dir__)
+
+# JSON Implementation for Ruby
+gem 'json', '~> 2.21'

gemfiles/json_3.gemfile

@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+# Variant of the main Gemfile which pins the json gem to its 3.x line. The
+# test matrix selects it through the BUNDLE_GEMFILE environment variable.
+eval_gemfile File.expand_path('../Gemfile', __dir__)
+
+# JSON Implementation for Ruby
+gem 'json', '~> 3.0'