Return 400 on bad names.

Cargo.lock

@@ -503,6 +503,15 @@ dependencies = [
  "winapi 0.3.9",
 ]
 
+[[package]]
+name = "claim"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "68ad37958d55b29a7088909368968d2fe876a24c203f8441195130f3b15194b9"
+dependencies = [
+ "autocfg",
+]
+
 [[package]]
 name = "config"
 version = "0.10.1"
@@ -2888,6 +2897,7 @@ dependencies = [
  "actix-rt",
  "actix-web",
  "chrono",
+ "claim",
  "config",
  "lazy_static",
  "reqwest",

Cargo.toml

@@ -33,3 +33,4 @@ unicode-segmentation = "1.7.1"
 [dev-dependencies]
 reqwest = { version = "0.10.7", features = ["json"] }
 lazy_static = "1.4.0"
+claim = "0.4.0"

src/domain.rs

@@ -5,6 +5,7 @@ pub struct NewSubscriber {
     pub name: SubscriberName,
 }
 
+#[derive(Debug)]
 pub struct SubscriberName(String);
 
 impl SubscriberName {
@@ -36,7 +37,7 @@ impl SubscriberName {
             > 0;
 
         if is_empty_or_whitespace || is_too_long || contains_forbidden_characters {
-            panic!(format!("{} is not a valid subscriber name.", s))
+            Err(format!("{} is not a valid subscriber name.", s))
         } else {
             Ok(Self(s))
         }
@@ -48,3 +49,47 @@ impl AsRef<str> for SubscriberName {
         &self.0
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use crate::domain::SubscriberName;
+    use claim::{assert_err, assert_ok};
+
+    #[test]
+    fn a_256_grapheme_long_name_is_valid() {
+        let name = "a̐".repeat(256);
+        assert_ok!(SubscriberName::parse(name));
+    }
+
+    #[test]
+    fn a_name_longer_than_256_graphemes_is_rejected() {
+        let name = "a".repeat(257);
+        assert_err!(SubscriberName::parse(name));
+    }
+
+    #[test]
+    fn whitespace_only_names_are_rejected() {
+        let name = " ".to_string();
+        assert_err!(SubscriberName::parse(name));
+    }
+
+    #[test]
+    fn empty_string_is_rejected() {
+        let name = "".to_string();
+        assert_err!(SubscriberName::parse(name));
+    }
+
+    #[test]
+    fn names_containing_an_invalid_characters_are_rejected() {
+        for name in vec!['/', '(', ')', '"', '<', '>', '\\', '{', '}'] {
+            let name = name.to_string();
+            assert_err!(SubscriberName::parse(name));
+        }
+    }
+
+    #[test]
+    fn a_valid_name_is_parsed_successfully() {
+        let name = "Ursula Le Guin".to_string();
+        assert_ok!(SubscriberName::parse(name));
+    }
+}

src/routes/subscriptions.rs

@@ -22,9 +22,11 @@ pub async fn subscribe(
     form: web::Form<FormData>,
     pool: web::Data<PgPool>,
 ) -> Result<HttpResponse, HttpResponse> {
+    let name =
+        SubscriberName::parse(form.0.name).map_err(|_| HttpResponse::BadRequest().finish())?;
     let new_subscriber = NewSubscriber {
         email: form.0.email,
-        name: SubscriberName::parse(form.0.name).expect("Name validation failed."),
+        name,
     };
     insert_subscriber(&pool, &new_subscriber)
         .await