Merge bundler to standard libraries.

rubygems 2.7.x depends bundler-1.15.x. This is preparation for
  rubygems and bundler migration.

  * lib/bundler.rb, lib/bundler/*: files of bundler-1.15.4
  * spec/bundler/*: rspec examples of bundler-1.15.4. I applied patches.
    * https://github.com/bundler/bundler/pull/6007
    * Exclude not working examples on ruby repository.
    * Fake ruby interpriter instead of installed ruby.
  * Makefile.in: Added test task named `test-bundler`. This task is only
    working macOS/linux yet. I'm going to support Windows environment later.
  * tool/sync_default_gems.rb: Added sync task for bundler.

  [Feature #12733][ruby-core:77172]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@59779 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

lib/bundler/cli/viz.rb

@@ -0,0 +1,30 @@
+# frozen_string_literal: true
+module Bundler
+  class CLI::Viz
+    attr_reader :options, :gem_name
+    def initialize(options)
+      @options = options
+    end
+
+    def run
+      # make sure we get the right `graphviz`. There is also a `graphviz`
+      # gem we're not built to support
+      gem "ruby-graphviz"
+      require "graphviz"
+
+      options[:without] = options[:without].join(":").tr(" ", ":").split(":")
+      output_file = File.expand_path(options[:file])
+
+      graph = Graph.new(Bundler.load, output_file, options[:version], options[:requirements], options[:format], options[:without])
+      graph.viz
+    rescue LoadError => e
+      Bundler.ui.error e.inspect
+      Bundler.ui.warn "Make sure you have the graphviz ruby gem. You can install it with:"
+      Bundler.ui.warn "`gem install ruby-graphviz`"
+    rescue StandardError => e
+      raise unless e.message =~ /GraphViz not installed or dot not in PATH/
+      Bundler.ui.error e.message
+      Bundler.ui.warn "Please install GraphViz. On a Mac with Homebrew, you can run `brew install graphviz`."
+    end
+  end
+end