Move to a helper and fix tests

test/configuration_test.rb

@@ -1,6 +1,6 @@
 require "webpacker_test_helper"
 
-class ConfigurationTest < Minitest::Test
+class ConfigurationTest < Webpacker::Test
   def test_source_path
     source_path = File.expand_path File.join(File.dirname(__FILE__), "test_app/app/javascript").to_s
     assert_equal source_path, Webpacker.config.source_path.to_s
@@ -39,18 +39,4 @@ def test_compile?
       refute reloaded_config.compile?
     end
   end
-
-  private
-    def with_node_env(env)
-      original = ENV["NODE_ENV"]
-      ENV["NODE_ENV"] = env
-      yield
-    ensure
-      ENV["NODE_ENV"] = original
-    end
-
-    def reloaded_config
-      Webpacker.instance.instance_variable_set(:@config, nil)
-      Webpacker.config
-    end
 end

test/dev_server_test.rb

@@ -1,11 +1,17 @@
 require "webpacker_test_helper"
 
-class DevServerTest < Minitest::Test
+class DevServerTest < Webpacker::Test
   def test_host
-    assert_equal "localhost", Webpacker.dev_server.host
+    with_node_env("development") do
+      reloaded_config
+      assert_equal Webpacker.dev_server.host, "localhost"
+    end
   end
 
   def test_port
-    assert_equal Webpacker.dev_server.port, 3035
+    with_node_env("development") do
+      reloaded_config
+      assert_equal Webpacker.dev_server.port, 3035
+    end
   end
 end

test/webpacker_test_helper.rb

@@ -20,5 +20,21 @@ class Application < ::Rails::Application
   end
 end
 
+class Webpacker::Test < Minitest::Test
+  private
+    def reloaded_config
+      Webpacker.instance.instance_variable_set(:@config, nil)
+      Webpacker.config
+    end
+
+    def with_node_env(env)
+      original = ENV["NODE_ENV"]
+      ENV["NODE_ENV"] = env
+      yield
+    ensure
+      ENV["NODE_ENV"] = original
+    end
+end
+
 Rails.backtrace_cleaner.remove_silencers!
 TestApp::Application.initialize!