feat!: [torrust#289] do not allow empty tag names

      It was allowed to use an empty strings like "" or " " for a tag name.

      From now on, it's not allowed.

      If there are some empty names in the database, they are not renamed.

      A migration to rename empty names was not added because there can be more than one tag, for example:

      - ""
      - " "
      - "  "
      - Etcetera

      We could have generated names like "no tag 1", "no tag 2", but it's not likely that admins have created empty tags.

src/errors.rs

@@ -136,6 +136,9 @@ pub enum ServiceError {
     #[display(fmt = "Tag already exists.")]
     TagAlreadyExists,
 
+    #[display(fmt = "Tag name cannot be empty.")]
+    TagNameEmpty,
+
     #[display(fmt = "Category not found.")]
     CategoryNotFound,
 
@@ -240,6 +243,7 @@ pub fn http_status_code_for_service_error(error: &ServiceError) -> StatusCode {
         ServiceError::TrackerOffline => StatusCode::INTERNAL_SERVER_ERROR,
         ServiceError::CategoryNameEmpty => StatusCode::BAD_REQUEST,
         ServiceError::CategoryAlreadyExists => StatusCode::BAD_REQUEST,
+        ServiceError::TagNameEmpty => StatusCode::BAD_REQUEST,
         ServiceError::TagAlreadyExists => StatusCode::BAD_REQUEST,
         ServiceError::InternalServerError => StatusCode::INTERNAL_SERVER_ERROR,
         ServiceError::EmailMissing => StatusCode::NOT_FOUND,

src/services/tag.rs

@@ -38,7 +38,13 @@ impl Service {
             return Err(ServiceError::Unauthorized);
         }
 
-        match self.tag_repository.add(tag_name).await {
+        let trimmed_name = tag_name.trim();
+
+        if trimmed_name.is_empty() {
+            return Err(ServiceError::TagNameEmpty);
+        }
+
+        match self.tag_repository.add(trimmed_name).await {
             Ok(()) => Ok(()),
             Err(e) => match e {
                 DatabaseError::TagAlreadyExists => Err(ServiceError::TagAlreadyExists),

tests/e2e/web/api/v1/contexts/tag/contract.rs

@@ -121,15 +121,17 @@ async fn it_should_allow_adding_duplicated_tags() {
 }
 
 #[tokio::test]
-async fn it_should_allow_adding_a_tag_with_an_empty_name() {
-    // code-review: is this an intended behavior?
-
+async fn it_should_not_allow_adding_a_tag_with_an_empty_name() {
     let mut env = TestEnv::new();
     env.start(api::Version::V1).await;
 
-    let empty_tag_name = String::new();
-    let response = add_tag(&empty_tag_name, &env).await;
-    assert_eq!(response.status, 200);
+    let invalid_tag_names = vec![String::new(), " ".to_string()];
+
+    for invalid_name in invalid_tag_names {
+        let response = add_tag(&invalid_name, &env).await;
+
+        assert_eq!(response.status, 400);
+    }
 }
 
 #[tokio::test]