Switch to using Bundler.with_original_env (#202)

This fixes a long-running issue with more recent Bundler versions and
compatibility with GitHub Actions (and other CI services), where the
environment wasn't being handled correctly.

Introduce a new 'APPRAISAL_UNDER_TEST' environment variable that
`Command` uses to determine if Appraisal itself is under test, and if
so, tweaks the environment in the way the tests require. This allows the
tests to pass while using `Bundler.with_original_env`.

Fixes #173

Co-authored-by: Kyle Fazzari <kyrofa@ubuntu.com>
Co-authored-by: Chris Oliver <excid3@gmail.com>

lib/appraisal/command.rb

@@ -3,23 +3,24 @@
 module Appraisal
   # Executes commands with a clean environment
   class Command
-    BUNDLER_ENV_VARS = %w(RUBYOPT BUNDLE_PATH BUNDLE_BIN_PATH BUNDLE_GEMFILE).freeze
-
-    attr_reader :command, :env, :gemfile, :original_env
+    attr_reader :command, :env, :gemfile
 
     def initialize(command, options = {})
       @gemfile = options[:gemfile]
       @env = options.fetch(:env, {})
       @command = command_starting_with_bundle(command)
-      @original_env = {}
     end
 
     def run
-      with_clean_env { ensure_bundler_is_available }
-      announce
+      run_env = test_environment.merge(env)
+
+      Bundler.with_original_env do
+        ensure_bundler_is_available
+        announce
 
-      with_clean_env do
-        env.each_pair do |key, value|
+        ENV["BUNDLE_GEMFILE"] = gemfile
+        ENV["APPRAISAL_INITIALIZED"] = "1"
+        run_env.each_pair do |key, value|
           ENV[key] = value
         end
 
@@ -31,15 +32,6 @@ def run
 
     private
 
-    def with_clean_env
-      unset_bundler_env_vars
-      ENV['BUNDLE_GEMFILE'] = gemfile
-      ENV['APPRAISAL_INITIALIZED'] = '1'
-      yield
-    ensure
-      restore_env
-    end
-
     def ensure_bundler_is_available
       version = Utils.bundler_version
       unless system %(gem list --silent -i bundler -v #{version})
@@ -66,17 +58,6 @@ def announce
       end
     end
 
-    def unset_bundler_env_vars
-      BUNDLER_ENV_VARS.each do |key|
-        original_env[key] = ENV[key]
-        ENV[key] = nil
-      end
-    end
-
-    def restore_env
-      original_env.each { |key, value| ENV[key] = value }
-    end
-
     def command_starts_with_bundle?(original_command)
       if original_command.is_a?(Array)
         original_command.first =~ /^bundle/
@@ -100,5 +81,14 @@ def command_as_string
         command
       end
     end
+
+    def test_environment
+      return {} unless ENV["APPRAISAL_UNDER_TEST"] == "1"
+
+      {
+        "GEM_HOME" => ENV["GEM_HOME"],
+        "GEM_PATH" => "",
+      }
+    end
   end
 end

spec/acceptance/bundle_without_spec.rb

@@ -39,7 +39,9 @@
     output = run "appraisal install --without drinks"
 
     expect(output).to include("Bundle complete")
-    expect(output).to include("Gems in the group drinks were not installed.")
+    expect(output).to(
+      match(/Gems in the group ['"]?drinks['"]? were not installed/),
+    )
     expect(output).not_to include("orange_juice")
     expect(output).not_to include("coffee")
     expect(output).not_to include("soda")

spec/spec_helper.rb

@@ -5,6 +5,7 @@
 
 PROJECT_ROOT = File.expand_path(File.join(File.dirname(__FILE__), '..')).freeze
 TMP_GEM_ROOT = File.join(PROJECT_ROOT, "tmp", "gems")
+ENV["APPRAISAL_UNDER_TEST"] = "1"
 
 RSpec.configure do |config|
   config.raise_errors_for_deprecations!