Update dependencies and implement email service integration

- Refactor app and email modules to include email service
- Add tests for user sign-up and mock email service

backend/src/email.rs

@@ -1,3 +1,5 @@
+use std::sync::Arc;
+
 use lettre::{
     AsyncTransport, Message, Tokio1Executor,
     transport::smtp::{AsyncSmtpTransport, authentication::Credentials},
@@ -18,33 +20,52 @@ pub enum Error {
     Email(#[from] lettre::error::Error),
 }
 
-/// A function to send an email using the given SMTP address.
-/// It may timeout if the SMTP server is not reachable, see [consts::SEND_EMAIL_TIMEOUT].
-pub async fn send_email(
-    email: &str,
-    title: &str,
-    message: &str,
-    smtp_relay_address: &str,
-    smtp_login: &str,
-    smtp_password: &str,
-) -> Result<(), Error> {
-    let email = Message::builder()
-        .message_id(None)
-        .from(consts::EMAIL_ADDRESS.parse()?)
-        .to(email.parse()?)
-        .subject(title)
-        .body(message.to_string())?;
-
-    let credentials = Credentials::new(smtp_login.to_string(), smtp_password.to_string());
-
-    let mailer = AsyncSmtpTransport::<Tokio1Executor>::relay(smtp_relay_address)?
-        .credentials(credentials)
-        .timeout(Some(consts::SEND_EMAIL_TIMEOUT))
-        .build();
-
-    if let Err(error) = mailer.send(email).await {
-        error!("Error when sending E-mail: {}", &error);
-    }
-
-    Ok(())
+#[async_trait::async_trait]
+pub trait EmailServiceTrait: Send + Sync {
+    async fn send_email(&self, email: &str, title: &str, message: &str) -> Result<(), Error>;
+}
+
+pub struct EmailService {
+    smtp_relay_address: String,
+    smtp_login: String,
+    smtp_password: String,
+}
+
+impl EmailService {
+    pub fn create_service(
+        smtp_relay_address: &str,
+        smtp_login: &str,
+        smtp_password: &str,
+    ) -> Arc<dyn EmailServiceTrait> {
+        Arc::new(Self {
+            smtp_relay_address: smtp_relay_address.to_string(),
+            smtp_login: smtp_login.to_string(),
+            smtp_password: smtp_password.to_string(),
+        })
+    }
+}
+
+#[async_trait::async_trait]
+impl EmailServiceTrait for EmailService {
+    /// A function to send an email using the given SMTP address.
+    /// It may timeout if the SMTP server is not reachable, see [consts::SEND_EMAIL_TIMEOUT].
+    async fn send_email(&self, email: &str, title: &str, message: &str) -> Result<(), Error> {
+        let email = Message::builder()
+            .message_id(None)
+            .from(consts::EMAIL_ADDRESS.parse()?)
+            .to(email.parse()?)
+            .subject(title)
+            .body(message.to_string())?;
+
+        let credentials = Credentials::new(self.smtp_login.clone(), self.smtp_password.clone());
+
+        let mailer = AsyncSmtpTransport::<Tokio1Executor>::relay(&self.smtp_relay_address)?
+            .credentials(credentials)
+            .timeout(Some(consts::SEND_EMAIL_TIMEOUT))
+            .build();
+
+        mailer.send(email).await?;
+
+        Ok(())
+    }
 }