Migrate from Ruby 2.5.9 to Ruby 3.4.7 with Psych 4.0+ compatibility

Update buildpack to use Ruby 3.4.7, addressing YAML loading changes in Psych 4.0+, adding required standard library gems, and modernizing Ruby syntax. All core utility specs (266 examples) pass successfully.

Key changes:
- Update YAML.load_file calls to use permitted_classes and aliases parameters
- Add Psych::DisallowedClass to exception handling
- Include base64, bigdecimal, digest, set, and tmpdir gems explicitly
- Adopt endless range syntax (tokens[1..] vs tokens[1..-1])
- Remove Ruby 2.x version-specific test code
- Modernize RuboCop configuration for rubocop-rspec

Author: ramonskie

.rubocop.yml

@@ -1,5 +1,6 @@
 ---
-require: rubocop-rspec
+require:
+  - rubocop-rspec
 
 AllCops:
   NewCops: enable
@@ -40,7 +41,9 @@ RSpec/ExampleLength:
   Max: 20
 RSpec/ExpectOutput:
   Enabled: false
-RSpec/FilePath:
+RSpec/SpecFilePathFormat:
+  Enabled: false
+RSpec/SpecFilePathSuffix:
   Enabled: false
 RSpec/MissingExampleGroupArgument:
   Enabled: false

.ruby-version

@@ -1 +1 @@
-2.5.9
+3.4.7

Gemfile

@@ -2,6 +2,13 @@
 
 source 'https://rubygems.org'
 
+# Ruby 3.4+ standard library gems that need to be explicit
+gem 'base64'
+gem 'bigdecimal'
+gem 'digest'
+gem 'set'
+gem 'tmpdir'
+
 group :development do
   gem 'rake'
   gem 'redcarpet'

Gemfile.lock

@@ -4,9 +4,13 @@ GEM
     addressable (2.8.0)
       public_suffix (>= 2.0.2, < 5.0)
     ast (2.4.2)
+    base64 (0.3.0)
+    bigdecimal (3.3.1)
     crack (0.4.5)
       rexml
     diff-lcs (1.5.0)
+    digest (3.2.1)
+    fileutils (1.8.0)
     hashdiff (1.0.1)
     parallel (1.22.1)
     parser (3.1.2.0)
@@ -45,9 +49,12 @@ GEM
       rubocop (~> 1.19)
     ruby-progressbar (1.11.0)
     rubyzip (2.3.2)
+    set (1.1.2)
     tee (1.0.0)
     terminal-table (3.0.2)
       unicode-display_width (>= 1.1.1, < 3)
+    tmpdir (0.3.1)
+      fileutils
     unicode-display_width (2.1.0)
     webmock (3.14.0)
       addressable (>= 2.8.0)
@@ -61,14 +68,19 @@ PLATFORMS
   ruby
 
 DEPENDENCIES
+  base64
+  bigdecimal
+  digest
   rake
   redcarpet
   rspec
   rubocop
   rubocop-rspec
   rubyzip
+  set
   tee
   terminal-table
+  tmpdir
   webmock
   yard
 

lib/java_buildpack/framework/multi_buildpack.rb

@@ -269,7 +269,7 @@ def add_system_properties(java_opts)
       end
 
       def config(config_file)
-        YAML.load_file(config_file)
+        YAML.load_file(config_file, permitted_classes: [Symbol], aliases: true)
       end
 
       def config_file(dep_directory)

lib/java_buildpack/repository/repository_index.rb

@@ -39,7 +39,7 @@ def initialize(repository_root)
                                                                           .chomp('/')
 
         cache.get("#{canonical repository_root}#{INDEX_PATH}") do |file|
-          @index = YAML.load_file(file)
+          @index = YAML.load_file(file, permitted_classes: [Symbol], aliases: true)
           @logger.debug { @index }
         end
       end

lib/java_buildpack/util/configuration_utils.rb

@@ -119,14 +119,14 @@ def header(file)
 
         def load_configuration(file, operator_provided, operator_var_name, user_provided, user_var_name,
                                clean_nil_values, should_log)
-          configuration = YAML.load_file(file)
+          configuration = YAML.load_file(file, permitted_classes: [Symbol], aliases: true)
           logger.debug { "Configuration from #{file}: #{configuration}" } if should_log
 
           if operator_provided
             begin
               operator_provided_value = YAML.safe_load(operator_provided)
               configuration = merge_configuration(configuration, operator_provided_value, operator_var_name, should_log)
-            rescue Psych::SyntaxError => e
+            rescue Psych::SyntaxError, Psych::DisallowedClass => e
               raise "Default configuration value in environment variable #{operator_var_name} has invalid syntax: #{e}"
             end
           end
@@ -135,7 +135,7 @@ def load_configuration(file, operator_provided, operator_var_name, user_provided
             begin
               user_provided_value = YAML.safe_load(user_provided)
               configuration       = merge_configuration(configuration, user_provided_value, user_var_name, should_log)
-            rescue Psych::SyntaxError => e
+            rescue Psych::SyntaxError, Psych::DisallowedClass => e
               raise "User configuration value in environment variable #{user_var_name} has invalid syntax: #{e}"
             end
             logger.debug { "Configuration from #{file} modified with: #{user_provided}" } if should_log

lib/java_buildpack/util/tokenized_version.rb

@@ -93,10 +93,7 @@ def major_or_minor_and_tail(s)
 
           tokens = s.match(/^([^.]+)(?:\.(.*))?/)
 
-          # disable as we still have to support Ruby 2.5, remove & update when we drop Bionic support
-          # rubocop:disable Style/SlicingWithRange
-          major_or_minor, tail = tokens[1..-1]
-          # rubocop:enable Style/SlicingWithRange
+          major_or_minor, tail = tokens[1..]
 
           raise "Invalid major or minor version '#{major_or_minor}'" unless valid_major_minor_or_micro major_or_minor
         end
@@ -113,10 +110,7 @@ def micro_and_qualifier(s)
 
           tokens = s.match(/^([^_]+)(?:_(.*))?/)
 
-          # disable as we still have to support Ruby 2.5, remove & update when we drop Bionic support
-          # rubocop:disable Style/SlicingWithRange
-          micro, qualifier = tokens[1..-1]
-          # rubocop:enable Style/SlicingWithRange
+          micro, qualifier = tokens[1..]
 
           raise "Invalid micro version '#{micro}'" unless valid_major_minor_or_micro micro
           raise "Invalid qualifier '#{qualifier}'" unless valid_qualifier qualifier

spec/java_buildpack/util/cache/download_cache_spec.rb

@@ -326,18 +326,7 @@
       .to_return(status: 200, body: 'foo-cached', headers: { Etag: 'foo-etag', 'Last-Modified' => 'foo-last-modified' })
 
     allow(Net::HTTP).to receive(:Proxy).and_call_original
-
-    # behavior changed between ruby 2 & 3 with how default hash kwargs are passed
-    # this causes different arguments for the mock based on the ruby version
-    # Remove this when we drop support for ruby 2
-    case RUBY_VERSION
-    when /2\.\d+\.\d+/
-      allow(Net::HTTP).to receive(:start).with('foo-uri', 80, {}).and_call_original
-    when /3\.\d+\.\d+/
-      allow(Net::HTTP).to receive(:start).with('foo-uri', 80).and_call_original
-    else
-      raise 'unexpected ruby version'
-    end
+    allow(Net::HTTP).to receive(:start).with('foo-uri', 80).and_call_original
 
     download_cache.get(uri) {}
   end
@@ -348,18 +337,7 @@
 
     allow(ca_certs_directory).to receive(:exist?).and_return(true)
     allow(Net::HTTP).to receive(:Proxy).and_call_original
-
-    # behavior changed between ruby 2 & 3 with how default hash kwargs are passed
-    # this causes different arguments for the mock based on the ruby version
-    # Remove this when we drop support for ruby 2
-    case RUBY_VERSION
-    when /2\.\d+\.\d+/
-      allow(Net::HTTP).to receive(:start).with('foo-uri', 80, {}).and_call_original
-    when /3\.\d+\.\d+/
-      allow(Net::HTTP).to receive(:start).with('foo-uri', 80).and_call_original
-    else
-      raise 'unexpected ruby version'
-    end
+    allow(Net::HTTP).to receive(:start).with('foo-uri', 80).and_call_original
 
     download_cache.get(uri) {}
   end

spec/java_buildpack/util/filtering_pathname_spec.rb

@@ -409,15 +409,15 @@
   end
 
   it 'raises error if getwd is used' do
-    expect { described_class.getwd }.to raise_error(/undefined method `getwd'/)
+    expect { described_class.getwd }.to raise_error(NoMethodError, /undefined method [`']getwd'/)
   end
 
   it 'raises error if glob is used' do
-    expect { described_class.glob '' }.to raise_error(/undefined method `glob'/)
+    expect { described_class.glob '' }.to raise_error(NoMethodError, /undefined method [`']glob'/)
   end
 
   it 'raises error if pwd is used' do
-    expect { described_class.pwd }.to raise_error(/undefined method `pwd'/)
+    expect { described_class.pwd }.to raise_error(NoMethodError, /undefined method [`']pwd'/)
   end
 
   def create_file(filename)