Add spec

spec/routing/hostname_constraints_spec.rb

@@ -16,4 +16,19 @@
       action: 'new'
     )
   end
+
+  example 'ホスト名が対象外なら errors/not_foundへ' do
+    expect(get: 'http://foo.example.jp').to route_to(
+      controller: 'errors',
+      action: 'routing_error'
+    )
+  end
+
+  example '存在しないパスならerrors/not_foundへ' do
+    expect(get: 'http://baukis.example.com/xyz').to route_to(
+      controller: 'errors',
+      action: 'routing_error',
+      anything: 'xyz'
+    )
+  end
 end