feat: add confirmation link in welcome email

Cargo.toml

@@ -49,6 +49,7 @@ features = ["json", "rustls-tls"]
 [dev-dependencies]
 claims = "0.7"
 fake = "~2.3"
+linkify = "0.9"
 once_cell = "1"
 quickcheck = "0.9.2"
 quickcheck_macros = "0.9.1"

src/routes/subscriptions.rs

@@ -45,12 +45,20 @@ pub async fn subscribe(
         return HttpResponse::InternalServerError().finish();
     }
 
+    let confirmation_link = "https://there-is-no-such-domain.com/subscriptions/confirm";
     if email_client
         .send_email(
             new_subscriber.email,
             "Welcome!",
-            "Welcome to our newsletter!",
-            "Welcome to our newsletter!",
+            &format!(
+                "Welcome to our newsletter!<br />\
+                Click <a href=\"{}\">here</a> to confirm your subscription.",
+                confirmation_link,
+            ),
+            &format!(
+                "Welcome to our newsletter!\nVisit {} to confirm your subscription.",
+                confirmation_link
+            ),
         )
         .await
         .is_err()

tests/api/subscriptions.rs

@@ -96,3 +96,39 @@ async fn subscribe_sends_a_confirmation_email_for_valid_data() {
     // Assert
     // Mock expectations are checked on drop.
 }
+
+#[tokio::test]
+async fn subscribe_sends_a_confirmation_email_with_a_link() {
+    // Arrange
+    let app = spawn_app().await;
+    let body = "name=le%20guin&email=ursula_le_guin%40gmail.com";
+
+    Mock::given(path("/emails"))
+        .and(method("POST"))
+        .respond_with(ResponseTemplate::new(200))
+        .mount(&app.email_server)
+        .await;
+
+    // Act
+    app.post_subscriptions(body.into()).await;
+
+    // Assert
+    let email_request = &app.email_server.received_requests().await.unwrap()[0];
+    let body: serde_json::Value = serde_json::from_slice(&email_request.body).unwrap();
+    let get_link = |s: &str| {
+        let links: Vec<_> = linkify::LinkFinder::new()
+            .links(s)
+            .filter(|l| *l.kind() == linkify::LinkKind::Url)
+            .collect();
+
+        assert_eq!(links.len(), 1);
+
+        links[0].as_str().to_owned()
+    };
+
+    let html_link = get_link(body["html"].as_str().unwrap());
+    let text_link = get_link(body["text"].as_str().unwrap());
+
+    // The two links should be identical.
+    assert_eq!(html_link, text_link);
+}