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

spec/bundler/install/allow_offline_install_spec.rb

@@ -0,0 +1,92 @@
+# frozen_string_literal: true
+require "spec_helper"
+
+RSpec.describe "bundle install with :allow_offline_install" do
+  before do
+    bundle "config allow_offline_install true"
+  end
+
+  context "with no cached data locally" do
+    it "still installs" do
+      install_gemfile! <<-G, :artifice => "compact_index"
+        source "http://testgemserver.local"
+        gem "rack-obama"
+      G
+      expect(the_bundle).to include_gem("rack 1.0")
+    end
+
+    it "still fails when the network is down" do
+      install_gemfile <<-G, :artifice => "fail"
+        source "http://testgemserver.local"
+        gem "rack-obama"
+      G
+      expect(out).to include("Could not reach host testgemserver.local.")
+      expect(the_bundle).to_not be_locked
+    end
+  end
+
+  context "with cached data locally" do
+    it "will install from the compact index" do
+      system_gems ["rack-1.0.0"]
+
+      install_gemfile! <<-G, :artifice => "compact_index"
+        source "http://testgemserver.local"
+        gem "rack-obama"
+        gem "rack", "< 1.0"
+      G
+
+      expect(the_bundle).to include_gems("rack-obama 1.0", "rack 0.9.1")
+
+      gemfile <<-G
+        source "http://testgemserver.local"
+        gem "rack-obama"
+      G
+
+      bundle! :update, :artifice => "fail"
+      expect(out).to include("Using the cached data for the new index because of a network error")
+
+      expect(the_bundle).to include_gems("rack-obama 1.0", "rack 1.0.0")
+    end
+
+    def break_git_remote_ops!
+      FileUtils.mkdir_p(tmp("broken_path"))
+      File.open(tmp("broken_path/git"), "w", 0o755) do |f|
+        f.puts strip_whitespace(<<-RUBY)
+          #!/usr/bin/env ruby
+          if %w(fetch --force --quiet --tags refs/heads/*:refs/heads/*).-(ARGV).empty? || %w(clone --bare --no-hardlinks --quiet).-(ARGV).empty?
+            warn "git remote ops have been disabled"
+            exit 1
+          end
+          ENV["PATH"] = ENV["PATH"].sub(/^.*?:/, "")
+          exec("git", *ARGV)
+        RUBY
+      end
+
+      old_path = ENV["PATH"]
+      ENV["PATH"] = "#{tmp("broken_path")}:#{ENV["PATH"]}"
+      yield if block_given?
+    ensure
+      ENV["PATH"] = old_path if block_given?
+    end
+
+    it "will install from a cached git repo" do
+      git = build_git "a", "1.0.0", :path => lib_path("a")
+      update_git("a", :path => git.path, :branch => "new_branch")
+      install_gemfile! <<-G
+        gem "a", :git => #{git.path.to_s.dump}
+      G
+
+      break_git_remote_ops! { bundle! :update }
+      expect(out).to include("Using cached git data because of network errors")
+      expect(the_bundle).to be_locked
+
+      break_git_remote_ops! do
+        install_gemfile! <<-G
+          gem "a", :git => #{git.path.to_s.dump}, :branch => "new_branch"
+        G
+      end
+      expect(out).to include("Using cached git data because of network errors")
+      expect(the_bundle).to be_locked
+    end
+  end
+end