test: add tests for Redis connection string with defaults and custom port

crates/backend/src/main.rs

@@ -157,8 +157,61 @@ mod tests {
     #[test]
     #[should_panic(expected = "DB_HOST must be set in .env")]
     fn build_database_url_missing_host_panics() {
-        with_vars_unset(["DB_HOST"], || {
+        // Clear the environment variable completely
+        unsafe { std::env::remove_var("DB_HOST") };
         build_database_url();
-        });
+    }
+
+    #[test]
+    fn connect_to_redis_database_with_defaults() {
+        // This test requires a running Redis instance
+        // We're mocking the successful connection here
+        with_vars(
+            [
+                ("REDIS_HOST", Some("localhost")),
+                ("REDIS_PORT", None::<&str>),
+            ],
+            || {
+                let expected_conn_string = "redis://localhost:6379";
+
+                // Just verify the connection string format is correct
+                // Actual connection would need integration tests
+                let redis_host = dotenvy::var("REDIS_HOST").unwrap_or_default();
+                let redis_port = dotenvy::var("REDIS_PORT")
+                    .map(|x| x.parse::<u16>().unwrap_or(6379))
+                    .unwrap_or(6379);
+                let actual_conn_string = format!("redis://{}:{}", redis_host, redis_port);
+
+                assert_eq!(
+                    actual_conn_string, expected_conn_string,
+                    "Redis connection string should use default port when not specified."
+                );
+            },
+        );
+    }
+
+    #[test]
+    fn connect_to_redis_database_with_custom_port() {
+        with_vars(
+            [
+                ("REDIS_HOST", Some("redis.internal")),
+                ("REDIS_PORT", Some("6380")),
+            ],
+            || {
+                let expected_conn_string = "redis://redis.internal:6380";
+
+                // Verify connection string format
+                let redis_host = dotenvy::var("REDIS_HOST").unwrap_or_default();
+                let redis_port = dotenvy::var("REDIS_PORT")
+                    .map(|x| x.parse::<u16>().unwrap_or(6379))
+                    .unwrap_or(6379);
+                let actual_conn_string = format!("redis://{}:{}", redis_host, redis_port);
+
+                assert_eq!(
+                    actual_conn_string, expected_conn_string,
+                    "Redis connection string should use specified host and port."
+                );
+            },
+        );
     }
 }