Add a way to use the latest appraisal each time

Author: mcmire

bin/rspec

@@ -0,0 +1,9 @@
+#!/usr/bin/env ruby
+
+require_relative "../support/current_bundle"
+
+current_bundle = SuperDiff::CurrentBundle.instance
+
+ENV["BUNDLE_GEMFILE"] ||= current_bundle.latest_appraisal.gemfile_path
+
+exec("bundle", "exec", "rspec", *ARGV)

spec/spec_helper.rb

@@ -10,9 +10,9 @@
 
 #---
 
-require_relative "support/current_bundle"
+require_relative "../support/current_bundle"
 
-SuperDiff::Test::CurrentBundle.instance.assert_appraisal!
+SuperDiff::CurrentBundle.instance.assert_appraisal!
 
 #---
 

spec/support/current_bundle.rb

@@ -0,0 +1,64 @@
+require "bundler"
+require "appraisal"
+require "shellwords"
+
+module SuperDiff
+  class CurrentBundle
+    include Singleton
+
+    ROOT_DIR = Pathname.new("../..").expand_path(__dir__)
+    APPRAISAL_GEMFILES_PATH = ROOT_DIR.join("gemfiles")
+
+    def assert_appraisal!
+      unless appraisal_in_use?
+        raise AppraisalNotSpecified.new(<<~MESSAGE)
+          Please run tests by specifying an appraisal, like:
+
+              bundle exec appraisal <appraisal_name> #{current_command}
+
+          Possible appraisals are:
+
+          #{available_appraisals.map { |appraisal| "- #{appraisal.name}\n" }.join}
+
+          Or to simply go with the latest appraisal, use:
+
+              bin/rspec #{current_command}
+        MESSAGE
+      end
+    end
+
+    def current_appraisal
+      if path
+        available_appraisals.find do |appraisal|
+          appraisal.gemfile_path == path.to_s
+        end
+      else
+        nil
+      end
+    end
+
+    def latest_appraisal
+      available_appraisals.max_by(&:name)
+    end
+
+    private
+
+    def appraisal_in_use?
+      !current_appraisal.nil?
+    end
+
+    def path
+      Bundler.default_gemfile
+    end
+
+    def available_appraisals
+      @_available_appraisals ||= Appraisal::AppraisalFile.new.appraisals
+    end
+
+    def current_command
+      Shellwords.join([File.basename($0)] + ARGV)
+    end
+
+    class AppraisalNotSpecified < ArgumentError; end
+  end
+end