Rails 5.1 以降で attribute_was, attribute_change, attribute_changed?, changed?, changed 等が DEPRECATION WARNINGRails 何が起きたか? Rails 5.1 へアップデートして大量に DEPRECATION WARNING や spec エラーが起きたので、調べてみると Rails 5.1 で ActiveRecord::AttributeMethods::Dirty の attribute_was attribute_change attribute_changed? changed? changed 辺りが非推奨になった。 参考: https://github.com/rails/rails/blob/ce93740a5e4437dfc1cf9b0b13da1bad06a2a598/
![Rails 5.1 以降で attribute_was, attribute_change, attribute_changed?, changed?, changed 等が DEPRECATION WARNING - Qiita](https://cdn-ak-scissors.b.st-hatena.com/image/square/4937b6c0c38071736c79f0a92b44f6748a2f4a3b/height=288;version=1;width=512/https%3A%2F%2Fqiita-user-contents.imgix.net%2Fhttps%253A%252F%252Fcdn.qiita.com%252Fassets%252Fpublic%252Farticle-ogp-background-412672c5f0600ab9a64263b751f1bc81.png%3Fixlib%3Drb-4.0.0%26w%3D1200%26mark64%3DaHR0cHM6Ly9xaWl0YS11c2VyLWNvbnRlbnRzLmltZ2l4Lm5ldC9-dGV4dD9peGxpYj1yYi00LjAuMCZ3PTk3MiZoPTM3OCZ0eHQ9UmFpbHMlMjA1LjElMjAlRTQlQkIlQTUlRTklOTklOEQlRTMlODElQTclMjBhdHRyaWJ1dGVfd2FzJTJDJTIwYXR0cmlidXRlX2NoYW5nZSUyQyUyMGF0dHJpYnV0ZV9jaGFuZ2VkJTNGJTJDJTIwY2hhbmdlZCUzRiUyQyUyMGNoYW5nZWQlMjAlRTclQUQlODklRTMlODElOEMlMjBERVBSRUNBJUUyJTgwJUE2JnR4dC1hbGlnbj1sZWZ0JTJDdG9wJnR4dC1jb2xvcj0lMjMyMTIxMjEmdHh0LWZvbnQ9SGlyYWdpbm8lMjBTYW5zJTIwVzYmdHh0LXNpemU9NTYmcz00ZmM0OTZlMjliMTM3MzA1NTQwMDE2MzdjYWRjODE5YQ%26mark-x%3D142%26mark-y%3D57%26blend64%3DaHR0cHM6Ly9xaWl0YS11c2VyLWNvbnRlbnRzLmltZ2l4Lm5ldC9-dGV4dD9peGxpYj1yYi00LjAuMCZoPTc2Jnc9NzcwJnR4dD0lNDBodHomdHh0LWNvbG9yPSUyMzIxMjEyMSZ0eHQtZm9udD1IaXJhZ2lubyUyMFNhbnMlMjBXNiZ0eHQtc2l6ZT0zNiZ0eHQtYWxpZ249bGVmdCUyQ3RvcCZzPTljYTYwNGFjNjhjZjNhMzgwNWVjOTc1NTM0NDgxZjUy%26blend-x%3D142%26blend-y%3D486%26blend-mode%3Dnormal%26s%3D9fba2e4a4861c3f78fdcd2030214c2cd)