Added unit tests for pure logic. Refs #2

Co-Authored-By: Claude Opus 5.5 <[email protected]>

src/backend/mail.rs

@@ -259,4 +259,86 @@ impl ForValidation for UpdateMessage {
     fn entity(&self) -> &dyn Validate {
         &self.message
     }
-}
+}
+
+#[cfg(all(test, feature = "ssr"))]
+mod tests {
+    use super::*;
+    use chrono::{NaiveDate, NaiveTime};
+    use crate::backend::data::{Reservation, ResProperty, ResWithProperty};
+
+    fn reservation() -> ResSumWithItems {
+        let mut property = ResProperty::default();
+        property.name = "Court 1".to_string();
+
+        let mut reservation = ResSumWithItems::default();
+        reservation.summary.date = NaiveDate::from_ymd_opt(2030, 3, 5).unwrap();
+        reservation.reservations.push(ResWithProperty {
+            reservation: Reservation::new(
+                NaiveTime::from_hms_opt(8, 0, 0).unwrap(),
+                NaiveTime::from_hms_opt(9, 30, 0).unwrap(),
+                1),
+            property
+        });
+
+        reservation
+    }
+
+    fn message(subject: &str, text: &str) -> Message {
+        let mut message = Message::default();
+        message.subject = subject.to_string();
+        message.text = text.to_string();
+
+        message
+    }
+
+    #[test]
+    fn mail_message_replaces_variables() {
+        let mail = MailMessage::new(
+            "[email protected]".to_string(),
+            "[email protected]".to_string(),
+            message("Booking", "Date: #date#, items: #summary#."),
+            &reservation());
+
+        assert_eq!(mail.subject, "Booking");
+        assert_eq!(mail.text, "Date: 05. 03. 2030, items: Court 1: 08:00 - 09:30.");
+    }
+
+    #[test]
+    fn mail_message_without_variables_is_unchanged() {
+        let mail = MailMessage::new(
+            "[email protected]".to_string(),
+            "[email protected]".to_string(),
+            message("Booking", "Plain text"),
+            &reservation());
+
+        assert_eq!(mail.text, "Plain text");
+    }
+
+    #[test]
+    fn build_mail_sets_headers() {
+        let mail = MailMessage::new(
+            "[email protected]".to_string(),
+            "[email protected]".to_string(),
+            message("Booking", "Hello"),
+            &reservation());
+
+        let built = String::from_utf8(mail.build_mail("[email protected]".to_string()).unwrap().formatted()).unwrap();
+
+        assert!(built.contains("From: [email protected]"));
+        assert!(built.contains("Reply-To: [email protected]"));
+        assert!(built.contains("To: [email protected]"));
+        assert!(built.contains("Subject: Booking"));
+    }
+
+    #[test]
+    fn build_mail_rejects_invalid_address() {
+        let mail = MailMessage::new(
+            "[email protected]".to_string(),
+            "not an address".to_string(),
+            message("Booking", "Hello"),
+            &reservation());
+
+        assert!(matches!(mail.build_mail("[email protected]".to_string()), Err(AppError::MailAddrParseErr(_))));
+    }
+}