Extract reusable code from doc tests

src/fixtures/personV1_V2.txt

@@ -0,0 +1,27 @@
+# use chrono::{DateTime, Utc};
+# use serde::{Deserialize, Serialize};
+# use std::convert::Infallible;
+#
+# #[derive(Deserialize, Serialize, Debug)]
+# #[serde(deny_unknown_fields)]
+# struct PersonV1 {
+#     name: String,
+# }
+#
+# #[derive(Deserialize, Serialize, Debug)]
+# #[serde(deny_unknown_fields)]
+# struct PersonV2 {
+#     name: String,
+#     updated_at: DateTime<Utc>,
+# }
+#
+# // First define how to map from one struct to another
+# impl From<PersonV1> for PersonV2 {
+#     fn from(value: PersonV1) -> Self {
+#         PersonV2 {
+#             name: value.name.clone(),
+#             updated_at: Utc::now(),
+#         }
+#     }
+# }
+#

src/fixtures/try_personV1_V2.txt

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+# use serde::{Deserialize, Serialize};
+# use std::convert::Infallible;
+#
+# #[derive(Deserialize, Serialize, Debug)]
+# #[serde(deny_unknown_fields)]
+# struct PersonV1 {
+#     name: String,
+#     title: Option<String>,
+# }
+#
+# #[derive(Deserialize, Serialize, Debug)]
+# #[serde(deny_unknown_fields)]
+# struct PersonV2 {
+#     name: String,
+#     job_title: String,
+# }
+#
+# #[derive(Debug, Eq, PartialEq)]
+# struct TitleCannotBeEmpty;
+#
+# impl From<TitleCannotBeEmpty> for PersonMigrationError {
+#     fn from(value: TitleCannotBeEmpty) -> Self {
+#         PersonMigrationError::TitleCannotBeEmpty
+#     }
+# }
+#
+# #[derive(thiserror::Error, Debug, Eq, PartialEq)]
+# enum PersonMigrationError {
+#     #[error("Title cannot be empty!!!")]
+#     TitleCannotBeEmpty,
+# }
+#
+# impl TryFrom<PersonV1> for PersonV2 {
+#     type Error = TitleCannotBeEmpty;
+#
+#     fn try_from(value: PersonV1) -> Result<Self, TitleCannotBeEmpty> {
+#         if let Some(title) = value.title {
+#             if title.is_empty() {
+#                 Err(TitleCannotBeEmpty)
+#             } else {
+#                 Ok(PersonV2 {
+#                     name: value.name,
+#                     job_title: title,
+#                 })
+#             }
+#         } else {
+#             Err(TitleCannotBeEmpty)
+#         }
+#     }
+# }