[rubygems/rubygems] Split out Gem::PathSupport#default_home_dir to fix "bundle doctor" specs.

https://github.com/rubygems/rubygems/commit/d7f3f901f1

lib/rubygems/path_support.rb

@@ -24,13 +24,7 @@ class Gem::PathSupport
   # hashtable, or defaults to ENV, the system environment.
   #
   def initialize(env)
-    @home = env["GEM_HOME"] || Gem.default_dir
-
-    if File::ALT_SEPARATOR
-      @home = @home.gsub(File::ALT_SEPARATOR, File::SEPARATOR)
-    end
-
-    @home = expand(@home)
+    @home = default_home_dir(env)
 
     # If @home (aka Gem.paths.home) exists, but we can't write to it,
     # fall back to Gem.user_dir (the directory used for user installs).
@@ -54,6 +48,20 @@ class Gem::PathSupport
 
   private
 
+  ##
+  # The default home directory.
+  # This function was broken out to accommodate tests in `bundler/spec/commands/doctor_spec.rb`.
+
+  def default_home_dir(env)
+    home = env["GEM_HOME"] || Gem.default_dir
+
+    if File::ALT_SEPARATOR
+      home = home.gsub(File::ALT_SEPARATOR, File::SEPARATOR)
+    end
+
+    expand(home)
+  end
+
   ##
   # Split the Gem search path (as reported by Gem.path).
 

spec/bundler/commands/doctor_spec.rb

@@ -38,6 +38,10 @@ RSpec.describe "bundle doctor" do
       allow(stat).to receive(:uid) { Process.uid }
       allow(File).to receive(:writable?).with(unwritable_file) { true }
       allow(File).to receive(:readable?).with(unwritable_file) { true }
+
+      # The following 2 lines are for `Gem::PathSupport#initialize`.
+      allow(File).to receive(:exist?).with(Gem.paths.send(:default_home_dir))
+      allow(File).to receive(:writable?).with(Gem.paths.send(:default_home_dir))
     end
 
     it "exits with no message if the installed gem has no C extensions" do