[rubygems/rubygems] Only activate bundler when needed

Loading Bundler beforehand was actually replacing ENV with a backup of
the pre-Bundler environment through `Bundler::EnvironmentPreserver`. I
think that was making a bug in `ENV.replace` not bite our tests, because
Bundler includes proper patches to workaround that issue. So this commit
also includes these patches in RubyGems tests.

https://github.com/rubygems/rubygems/commit/8e079149b9

test/rubygems/helper.rb

@@ -2,21 +2,11 @@
 
 require "rubygems"
 
-# If bundler gemspec exists, add to stubs
-bundler_gemspec = File.expand_path("../../bundler/bundler.gemspec", __dir__)
-if File.exist?(bundler_gemspec)
-  Gem::Specification.dirs.unshift File.dirname(bundler_gemspec)
-  Gem::Specification.class_variable_set :@@stubs, nil
-  Gem::Specification.stubs
-  Gem::Specification.dirs.shift
-end
-
 begin
   gem "test-unit", "~> 3.0"
 rescue Gem::LoadError
 end
 
-require "bundler"
 require "test/unit"
 
 ENV["JARS_SKIP"] = "true" if Gem.java_platform? # avoid unnecessary and noisy `jar-dependencies` post install hook
@@ -404,7 +394,6 @@ class Gem::TestCase < Test::Unit::TestCase
     Gem.loaded_specs.clear
     Gem.instance_variable_set(:@activated_gem_paths, 0)
     Gem.clear_default_specs
-    Bundler.reset!
 
     Gem.configuration.verbose = true
     Gem.configuration.update_sources = true
@@ -460,7 +449,7 @@ class Gem::TestCase < Test::Unit::TestCase
 
     FileUtils.rm_rf @tempdir
 
-    ENV.replace(@orig_env)
+    restore_env
 
     Gem::ConfigFile.send :remove_const, :SYSTEM_WIDE_CONFIG_FILE
     Gem::ConfigFile.send :const_set, :SYSTEM_WIDE_CONFIG_FILE,
@@ -1581,6 +1570,23 @@ Also, a list:
     PUBLIC_KEY  = nil
     PUBLIC_CERT = nil
   end if Gem::HAVE_OPENSSL
+
+  private
+
+  def restore_env
+    unless Gem.win_platform?
+      ENV.replace(@orig_env)
+      return
+    end
+
+    # Fallback logic for Windows below to workaround
+    # https://bugs.ruby-lang.org/issues/16798. Can be dropped once all
+    # supported rubies include the fix for that.
+
+    ENV.clear
+
+    @orig_env.each {|k, v| ENV[k] = v }
+  end
 end
 
 # https://github.com/seattlerb/minitest/blob/13c48a03d84a2a87855a4de0c959f96800100357/lib/minitest/mock.rb#L192

test/rubygems/test_gem.rb

@@ -615,6 +615,7 @@ class TestGem < Gem::TestCase
   end
 
   def test_self_use_gemdeps
+    with_local_bundler do
       with_rubygems_gemdeps("-") do
         FileUtils.mkdir_p "detect/a/b"
         FileUtils.mkdir_p "detect/a/Isolate"
@@ -632,6 +633,7 @@ class TestGem < Gem::TestCase
         end
       end
     end
+  end
 
   def test_self_dir
     assert_equal @gemhome, Gem.dir
@@ -773,6 +775,7 @@ class TestGem < Gem::TestCase
   end
 
   def test_self_find_files_with_gemfile
+    with_local_bundler do
       cwd = File.expand_path("test/rubygems", PROJECT_DIR)
       actual_load_path = $LOAD_PATH.unshift(cwd).dup
 
@@ -806,6 +809,7 @@ class TestGem < Gem::TestCase
       assert_equal expected, Gem.find_files("sff/**.rb").sort, "[ruby-core:31730]"
       assert_equal cwd, actual_load_path.shift
     end
+  end
 
   def test_self_find_latest_files
     cwd = File.expand_path("test/rubygems", PROJECT_DIR)
@@ -1631,6 +1635,7 @@ class TestGem < Gem::TestCase
   end
 
   def test_auto_activation_of_specific_gemdeps_file
+    with_local_bundler do
       a = util_spec "a", "1", nil, "lib/a.rb"
       b = util_spec "b", "1", nil, "lib/b.rb"
       c = util_spec "c", "1", nil, "lib/c.rb"
@@ -1651,8 +1656,10 @@ class TestGem < Gem::TestCase
         assert_equal add_bundler_full_name(%W[a-1 b-1 c-1]), loaded_spec_names
       end
     end
+  end
 
   def test_auto_activation_of_used_gemdeps_file
+    with_local_bundler do
       a = util_spec "a", "1", nil, "lib/a.rb"
       b = util_spec "b", "1", nil, "lib/b.rb"
       c = util_spec "c", "1", nil, "lib/c.rb"
@@ -1675,6 +1682,7 @@ class TestGem < Gem::TestCase
         assert_equal expected_specs, loaded_spec_names
       end
     end
+  end
 
   def add_bundler_full_name(names)
     names << "bundler-#{Bundler::VERSION}".freeze
@@ -1683,6 +1691,7 @@ class TestGem < Gem::TestCase
   end
 
   def test_looks_for_gemdeps_files_automatically_from_binstubs
+    with_local_bundler do
       a = util_spec "a", "1" do |s|
         s.executables = %w[foo]
         s.bindir = "exe"
@@ -1728,8 +1737,10 @@ class TestGem < Gem::TestCase
         assert_equal ["b-1", "c-1"], out - out0
       end
     end
+  end
 
   def test_looks_for_gemdeps_files_automatically_from_binstubs_in_parent_dir
+    with_local_bundler do
       pend "IO.popen has issues on JRuby when passed :chdir" if Gem.java_platform?
 
       a = util_spec "a", "1" do |s|
@@ -1781,6 +1792,7 @@ class TestGem < Gem::TestCase
         assert_equal ["b-1", "c-1"], out - out0
       end
     end
+  end
 
   def test_register_default_spec
     Gem.clear_default_specs
@@ -1823,6 +1835,7 @@ class TestGem < Gem::TestCase
   end
 
   def test_use_gemdeps
+    with_local_bundler do
       gem_deps_file = "gem.deps.rb".tap(&Gem::UNTAINT)
       spec = util_spec "a", 1
       install_specs spec
@@ -1841,8 +1854,10 @@ class TestGem < Gem::TestCase
       assert_equal add_bundler_full_name(%W[a-1]), loaded_spec_names
       refute_nil Gem.gemdeps
     end
+  end
 
   def test_use_gemdeps_ENV
+    with_local_bundler do
       with_rubygems_gemdeps(nil) do
         spec = util_spec "a", 1
 
@@ -1857,8 +1872,10 @@ class TestGem < Gem::TestCase
         refute spec.activated?
       end
     end
+  end
 
   def test_use_gemdeps_argument_missing
+    with_local_bundler do
       e = assert_raise ArgumentError do
         Gem.use_gemdeps "gem.deps.rb"
       end
@@ -1866,8 +1883,10 @@ class TestGem < Gem::TestCase
       assert_equal "Unable to find gem dependencies file at gem.deps.rb",
                    e.message
     end
+  end
 
   def test_use_gemdeps_argument_missing_match_ENV
+    with_local_bundler do
       with_rubygems_gemdeps("gem.deps.rb") do
         e = assert_raise ArgumentError do
           Gem.use_gemdeps "gem.deps.rb"
@@ -1877,8 +1896,10 @@ class TestGem < Gem::TestCase
                      e.message
       end
     end
+  end
 
   def test_use_gemdeps_automatic
+    with_local_bundler do
       with_rubygems_gemdeps("-") do
         spec = util_spec "a", 1
         install_specs spec
@@ -1895,16 +1916,20 @@ class TestGem < Gem::TestCase
         assert_equal add_bundler_full_name(%W[a-1]), loaded_spec_names
       end
     end
+  end
 
   def test_use_gemdeps_automatic_missing
+    with_local_bundler do
       with_rubygems_gemdeps("-") do
         Gem.use_gemdeps
 
         assert true # count
       end
     end
+  end
 
   def test_use_gemdeps_disabled
+    with_local_bundler do
       with_rubygems_gemdeps("") do
         spec = util_spec "a", 1
 
@@ -1919,8 +1944,10 @@ class TestGem < Gem::TestCase
         refute spec.activated?
       end
     end
+  end
 
   def test_use_gemdeps_missing_gem
+    with_local_bundler do
       with_rubygems_gemdeps("x") do
         File.open "x", "w" do |io|
           io.write 'gem "a"'
@@ -1941,8 +1968,10 @@ You may need to `bundle install` to install missing gems
         end
       end
     end
+  end
 
   def test_use_gemdeps_specific
+    with_local_bundler do
       with_rubygems_gemdeps("x") do
         spec = util_spec "a", 1
         install_specs spec
@@ -1959,6 +1988,7 @@ You may need to `bundle install` to install missing gems
         assert_equal add_bundler_full_name(%W[a-1]), loaded_spec_names
       end
     end
+  end
 
   def test_operating_system_defaults
     operating_system_defaults = Gem.operating_system_defaults
@@ -2090,4 +2120,21 @@ You may need to `bundle install` to install missing gems
   ensure
     ENV["RUBYGEMS_GEMDEPS"] = rubygems_gemdeps
   end
+
+  def with_local_bundler
+    # If bundler gemspec exists, add to stubs
+    bundler_gemspec = File.expand_path("../../bundler/bundler.gemspec", __dir__)
+    if File.exist?(bundler_gemspec)
+      Gem::Specification.dirs.unshift File.dirname(bundler_gemspec)
+      Gem::Specification.class_variable_set :@@stubs, nil
+      Gem::Specification.stubs
+      Gem::Specification.dirs.shift
+    end
+
+    require "bundler"
+
+    yield
+  ensure
+    Bundler.reset!
+  end
 end