Add spec helper to generate gems for integration testing

spec/spec_helper.rb

@@ -18,5 +18,6 @@ def load_support_files!
   config.order = :random
 
   config.include FileHelper
+  config.include GemHelper
   config.include TempDirHelper
 end

spec/support/gem_helper.rb

@@ -0,0 +1,21 @@
+require "tmpdir"
+
+module GemHelper
+  RSpec.configure do |config|
+    config.around(with_gem: true) do |spec|
+      self.class.class_eval { attr_reader :gem }
+
+      Dir.mktmpdir do |dir|
+        @gem = Kangaru::Testing::Gem.new(dir:).tap(&:create!)
+
+        spec.run
+
+        Object.send(:remove_const, :SomeGem) if Object.const_defined?(:SomeGem)
+
+        if Kangaru.instance_variable_defined?(:@application)
+          Kangaru.remove_instance_variable(:@application)
+        end
+      end
+    end
+  end
+end