remove workarounds for Ruby < 2.3

- remove constants for differentiating between Ruby versions
- remove fallback assignment for RUBY_ENGINE constant
- remove rubygems require
- use unicode character properties in regular expressions (e.g., \p{Word})
- remove COERCE_ENCODING constant
- always set FORCE_ENCODING constant to true unless default external encoding is not UTF-8
- remove workaround for computing line length
- use lines method instead of lines.entries to get lines for string
- always normalize lines
- check if JRuby class is defined instead of checking for JRuby engine
- remove global RUBY_ENGINE_JRUBY constant
- move RUBY_ENGINE_OPAL constant inside Asciidoctor module
- remove magic encoding comments (since default script encoding is UTF-8)
- remove workaround when printing encoding information
- remove fallback assignments for passthrough escape characters
- remove Ruby core backports (only leave Asciidoctor-specific extensions)
- use __dir__ instead of File.dirname __FILE__
- use Float#truncate to truncate column widths
- override Float#truncate on Ruby 2.3 to implement precision argument
- remove concurrent/hash backport
- simplify class_for_name helper
- don't call to_sym on constants returned from constants method
- remove unnecessary aliasing of regexp match variables; use magic variable instead (e.g., m = $~)
- remove workaround for sub_specialchars to accomodate gsub with map argument
- remove comment about %:z placeholder for strftime
- don't call .to_a on return value of Hash#keys
- get home directory using Dir.home
- remove exceptions and exclusions for Ruby < 2 in test suite
- update list of supported Ruby engines and versions in READMEs
- update ruby versions in run-tests.sh

1 files changed, 3 insertions, 4 deletions

diff --git a/test/parser_test.rb b/test/parser_test.rb
index 2e96bef1..59c67ec6 100644
--- a/test/parser_test.rb
+++ b/test/parser_test.rb
@@ -1,4 +1,3 @@
-# encoding: UTF-8
 unless defined? ASCIIDOCTOR_PROJECT_DIR
   $: << File.dirname(__FILE__); $:.uniq!
   require 'test_helper'
@@ -298,7 +297,7 @@ context "Parser" do
     assert_equal 'Stéphane', metadata['firstname']
     assert_equal 'Brontë', metadata['lastname']
     assert_equal 'SB', metadata['authorinitials']
-  end if ::RUBY_MIN_VERSION_1_9
+  end
 
   test 'parse ideographic author names' do
     metadata, _ = parse_header_metadata '李 四 <si.li@example.com>'
@@ -310,7 +309,7 @@ context "Parser" do
     assert_equal '四', metadata['lastname']
     assert_equal 'si.li@example.com', metadata['email']
     assert_equal '李四', metadata['authorinitials']
-  end if ::RUBY_MIN_VERSION_1_9
+  end
 
   test "parse author condenses whitespace" do
     metadata, _ = parse_header_metadata '   Stuart       Rackham     <founder@asciidoc.org>'
@@ -710,7 +709,7 @@ devtmpfs                3.9G       0     3.9G     0%    /dev
 
     expected = input
 
-    lines = input.lines.entries
+    lines = input.lines
     Asciidoctor::Parser.adjust_indentation! lines, -1
     assert_equal expected, lines.join
   end