add errors controller with error pages for 404 500 422

test/controllers/errors_controller_test.rb

@@ -0,0 +1,14 @@
+require 'test_helper'
+
+class ErrorsControllerTest < ActionController::TestCase
+  test "should get not_found" do
+    get :not_found
+    assert_response :success
+  end
+
+  test "should get error" do
+    get :error
+    assert_response :success
+  end
+
+end