see #363: drop dependency on kindlegen gem to unblock CI (#364)

.github/workflows/ci.yml

@@ -20,10 +20,6 @@ jobs:
         ruby: [jruby, 2.3, 2.4, 2.5, 2.6, 2.7]
         platform: [ubuntu-latest, macos-latest, windows-latest]
         asciidoctor: [1.5.6, '']
-        exclude:
-          # kindlegen fails to install on 2.3 on Windows. See https://github.com/asciidoctor/asciidoctor-epub3/pull/213
-          - ruby: 2.3
-            platform: windows-latest
     runs-on: ${{ matrix.platform }}
     steps:
       - name: Checkout

Gemfile

@@ -14,7 +14,4 @@ end
 group :optional do
   # epubcheck-ruby might be safe to be converted into runtime dependency, but could have issues when packaged into asciidoctorj-epub3
   gem 'epubcheck-ruby', '~> 4.2.4.0'
-  # We would like to make kindlegen a runtime dependency, but can't because of the way asciidoctorj-epub3 packaging works
-  # See https://github.com/asciidoctor/asciidoctor-epub3/issues/288
-  gem 'kindlegen', '~> 3.0.3'
 end

lib/asciidoctor-epub3/converter.rb

@@ -1638,15 +1638,8 @@ def get_kindlegen_command kindlegen_path
           return [result]
         end
 
-        begin
-          require 'kindlegen' unless defined? ::Kindlegen
-          result = ::Kindlegen.command.to_s
-          logger.debug %(Using KindleGen from gem: #{result})
-          [result]
-        rescue LoadError => e
-          logger.debug %(#{e}; Using KindleGen from PATH)
-          [%(kindlegen#{::Gem.win_platform? ? '.exe' : ''})]
-        end
+        logger.debug 'Using KindleGen from PATH'
+        [%(kindlegen#{::Gem.win_platform? ? '.exe' : ''})]
       end
 
       def distill_epub_to_mobi epub_file, target, compress, kindlegen_path

spec/spec_helper.rb

@@ -69,13 +69,8 @@ def skip_unless_has_logger
     skip 'Logger is unavailable on Asciidoctor < 1.5.7' unless has_logger?
   end
 
-  def darwin_platform?
-    RbConfig::CONFIG['host_os'] =~ /darwin/
-  end
-
   def skip_unless_has_kindlegen
-    # TODO: https://github.com/asciidoctor/asciidoctor-epub3/issues/236
-    skip '#236: Kindlegen is unavailable for 64-bit MacOS' if darwin_platform?
+    skip 'KindleGen is gone: https://github.com/asciidoctor/asciidoctor-epub3/issues/363'
   end
 
   def convert input, opts = {}