Drop Ruby 2.7/3.0 support

Set the minimum Ruby version to 3.1, update the dev environment and CI
matrices, bump the library version to 3.0.0pre, and refresh documentation
and lockfile metadata accordingly.

Author: evolve75

.github/workflows/coveralls.yml

@@ -21,7 +21,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ruby: ["2.7", "3.0", "3.1", "3.2", "3.3", "3.4"]
+        ruby: ["3.1", "3.2", "3.3", "3.4"]
     runs-on: ubuntu-latest
 
     steps:

.github/workflows/ruby.yml

@@ -9,7 +9,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ruby: ["2.7", "3.0", "3.1", "3.2", "3.3", "3.4"]
+        ruby: ["3.1", "3.2", "3.3", "3.4"]
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2

.ruby-version

@@ -1 +1 @@
-ruby-2.7.2
+ruby-3.1.0

API-CHANGES.md

@@ -29,6 +29,10 @@ smooth transition to the new APIs.
 * [Tree::TreeNode#each_level][each_level] now returns a level-wise enumerator
   when called without a block.
 
+## Release 3.0.0 Changes
+
+* Minimum Ruby version is now 3.1 (support for 2.7 and 3.0 has been dropped).
+
 ## Release 2.1.0 Changes
 
 * Minimum Ruby version has been bumped to 2.7 and above

Gemfile.lock

@@ -1,7 +1,7 @@
 PATH
   remote: .
   specs:
-    rubytree (2.2.1pre)
+    rubytree (3.0.0pre)
       json (~> 2.18)
 
 GEM
@@ -91,7 +91,7 @@ PLATFORMS
   ruby
 
 DEPENDENCIES
-  bundler (~> 2.3)
+  bundler (~> 2.6)
   rake (~> 13.3)
   rdoc (~> 7.1)
   rspec (~> 3.13)
@@ -106,4 +106,4 @@ DEPENDENCIES
   yard (~> 0.9)
 
 BUNDLED WITH
-   2.3.4
+   2.6.9

History.md

@@ -6,6 +6,10 @@
   compatibility. Some upstream updates (e.g., `diff-lcs` 2.x, `erb` 6.x) remain
   on current versions due to Ruby 2.7 support.
 
+### 3.0.0pre / 2026-02-07
+
+* Drop support for Ruby 2.7 and 3.0. Minimum required version is now 3.1.
+
 ### 2.2.0 / 2026-02-06
 
 * Prevent cycles by rejecting attempts to add an ancestor as a child.

README.md

@@ -117,8 +117,7 @@ This example can also be found at
 
 ## REQUIREMENTS: ##
 
-* [Ruby][] 2.7.x and above.
-
+* [Ruby][] 3.1.x and above. Ruby 2.7 and 3.0 are supported by RubyTree 2.2.0.
 
 * Run-time Dependencies:
 

lib/tree/version.rb

@@ -35,5 +35,5 @@
 
 module Tree
   # Rubytree Package Version
-  VERSION = '2.2.1pre'
+  VERSION = '3.0.0pre'
 end

rubytree.gemspec

@@ -19,7 +19,7 @@ Gem::Specification.new do |s|
   s.email                 = 'anupamsg@gmail.com'
   s.homepage              = 'http://rubytree.anupamsg.me'
 
-  s.required_ruby_version = '>=2.7'
+  s.required_ruby_version = '>=3.1'
 
   s.summary               = 'A generic tree data structure for Ruby.'
 
@@ -67,7 +67,7 @@ Gem::Specification.new do |s|
   s.add_runtime_dependency 'json', '~> 2.18'
 
   # NOTE: Rake is added as a development and test dependency in the Gemfile.
-  s.add_development_dependency 'bundler', '~> 2.3'
+  s.add_development_dependency 'bundler', '~> 2.6'
   s.add_development_dependency 'rake', '~> 13.3'
   s.add_development_dependency 'rdoc', '~> 7.1'
   s.add_development_dependency 'rspec', '~> 3.13'
@@ -86,6 +86,8 @@ Gem::Specification.new do |s|
 
     Note::
 
+    - 3.0.0pre sets the minimum Ruby version to 3.1.
+
     - 2.2.0 is a minor update that improves tree integrity checks,
             traversal robustness, and node management edge cases.