add ruby 2.2, 2.3, and 2.4 to CI matrix

.github/workflows/development.yml

@@ -14,6 +14,9 @@ jobs:
           - macos
 
         ruby:
+          - 2.2
+          - 2.3
+          - 2.4
           - 2.5
           - 2.6
           - 2.7

Gemfile

@@ -26,14 +26,16 @@ group :test do
   gem 'rspec', '~> 3.3'
 end
 
+RUBY_VERSION_FLOAT = RUBY_VERSION[/\d+\.\d+/].to_f
+
 group :development do
   gem 'bundler'
   gem 'gems', require: false
   gem 'guard-rspec', require: false
-  gem 'guard-rubocop'
+  gem 'guard-rubocop' unless RUBY_VERSION_FLOAT < 2.4
   gem 'netrc', require: false
   gem 'octokit', require: false
   gem 'pry-rescue'
-  gem 'rubocop', '0.91.0'
+  gem 'rubocop', '0.91.0' unless RUBY_VERSION_FLOAT < 2.4
   gem 'yard', require: false
 end

lib/listen/adapter/base.rb

@@ -88,7 +88,7 @@ def stop
       private
 
       def _stop
-        @run_thread&.kill
+        @run_thread && @run_thread.kill
         @run_thread = nil
       end
 

lib/listen/adapter/darwin.rb

@@ -69,7 +69,7 @@ def _process_event(dir, path)
       end
 
       def _stop
-        @worker_thread&.kill
+        @worker_thread && @worker_thread.kill
         super
       end
     end

lib/listen/adapter/linux.rb

@@ -102,7 +102,7 @@ def _dir_event?(event)
       end
 
       def _stop
-        @worker&.close
+        @worker && @worker.close
 
         super
       end

lib/listen/event/config.rb

@@ -25,7 +25,7 @@ def sleep(seconds)
       end
 
       def call(*args)
-        @block&.call(*args)
+        @block && @block.call(*args)
       end
 
       def callable?

lib/listen/event/loop.rb

@@ -29,7 +29,7 @@ def initialize(config)
       end
 
       def wakeup_on_event
-        if started? && @wait_thread&.alive?
+        if started? && @wait_thread && @wait_thread.alive?
           _wakeup(:event)
         end
       end
@@ -67,7 +67,7 @@ def pause
       def stop
         transition! :stopped
 
-        @wait_thread&.join
+        @wait_thread && @wait_thread.join
         @wait_thread = nil
       end
 

lib/listen/record.rb

@@ -45,16 +45,16 @@ def file_data(rel_path)
     end
 
     def dir_entries(rel_path)
-      subtree = if ['', '.'].include? rel_path.to_s
+      subtree = if ['', '.'].include?(rel_path.to_s)
         @tree
       else
         @tree[rel_path.to_s] ||= _auto_hash
         @tree[rel_path.to_s]
       end
 
-      subtree.transform_values do |values|
+      subtree.each_with_object({}) do |(key, values), result|
         # only get data for file entries
-        values.key?(:mtime) ? values : {}
+        result[key] = values.has_key?(:mtime) ? values : {}
       end
     end
 

lib/listen/thread.rb

@@ -17,7 +17,7 @@ def new(name, &block)
         ::Thread.new do
           rescue_and_log(thread_name, caller_stack: caller_stack, &block)
         end.tap do |thread|
-          thread.name = thread_name
+          thread.name = thread_name unless RUBY_VERSION[/\d+\.\d+/].to_f < 2.3
         end
       end
       # rubocop:enable Style/MultilineBlockChain
@@ -41,7 +41,12 @@ def _log_exception(exception, thread_name, caller_stack: nil)
       end
 
       def _exception_with_causes(exception)
-        result = +"#{exception.class}: #{exception}"
+        result =
+          if RUBY_VERSION[/\d+\.\d+/].to_f < 2.3
+            "#{exception.class}: #{exception}"
+          else
+            +"#{exception.class}: #{exception}"
+          end
         if exception.cause
           result << "\n"
           result << "--- Caused by: ---\n"

spec/lib/listen/thread_spec.rb

@@ -43,7 +43,7 @@
       end
 
       it "rescues and logs exceptions" do
-        pattern = <<~EOS.strip
+        pattern = <<-EOS.gsub(/^ +/, '').strip
           Exception rescued in listen-worker_thread:
           ArgumentError: boom!
           .*\\/listen\\/thread_spec\\.rb
@@ -53,7 +53,7 @@
       end
 
       it "rescues and logs backtrace + exception backtrace" do
-        pattern = <<~EOS.strip
+        pattern = <<-EOS.gsub(/^ +/, '').strip
           Exception rescued in listen-worker_thread:
           ArgumentError: boom!
           .*\\/listen\\/thread\\.rb.*--- Thread.new ---.*\\/listen\\/thread_spec\\.rb
@@ -93,7 +93,7 @@ class TestExceptionDerivedFromException < Exception; end # rubocop:disable Lint/
       let(:block) { raise_nested_exception_block }
 
       it "details exception causes" do
-        pattern = <<~EOS
+        pattern = <<-EOS.gsub(/^ +/, '')
           RuntimeError: nested outer
           --- Caused by: ---
           RuntimeError: nested inner
@@ -108,7 +108,7 @@ class TestExceptionDerivedFromException < Exception; end # rubocop:disable Lint/
 
   describe '.rescue_and_log' do
     it 'rescues and logs nested exceptions' do
-      pattern = <<~EOS
+      pattern = <<-EOS.gsub(/^ +/, '')
         Exception rescued in method:
         RuntimeError: nested outer
         --- Caused by: ---