diff --git a/src/core/authentication/handler.rs b/src/core/authentication/handler.rs
index f327c4fd..3ada2b11 100644
--- a/src/core/authentication/handler.rs
+++ b/src/core/authentication/handler.rs
@@ -231,3 +231,136 @@ impl KeysHandler {
         Ok(())
     }
 }
+
+#[cfg(test)]
+mod tests {
+
+    mod the_keys_handler_when_tracker_is_configured_as_private {
+
+        use std::sync::Arc;
+
+        use torrust_tracker_configuration::v2_0_0::core::PrivateMode;
+        use torrust_tracker_configuration::Configuration;
+        use torrust_tracker_test_helpers::configuration;
+
+        use crate::core::authentication::handler::KeysHandler;
+        use crate::core::authentication::key::repository::in_memory::InMemoryKeyRepository;
+        use crate::core::authentication::key::repository::persisted::DatabaseKeyRepository;
+        use crate::core::services::initialize_database;
+
+        fn instantiate_keys_handler() -> KeysHandler {
+            let config = configuration::ephemeral_private();
+
+            instantiate_keys_handler_with_configuration(&config)
+        }
+
+        #[allow(dead_code)]
+        fn instantiate_keys_handler_with_checking_keys_expiration_disabled() -> KeysHandler {
+            let mut config = configuration::ephemeral_private();
+
+            config.core.private_mode = Some(PrivateMode {
+                check_keys_expiration: false,
+            });
+
+            instantiate_keys_handler_with_configuration(&config)
+        }
+
+        fn instantiate_keys_handler_with_configuration(config: &Configuration) -> KeysHandler {
+            let database = initialize_database(config);
+
+            let db_key_repository = Arc::new(DatabaseKeyRepository::new(&database));
+            let in_memory_key_repository = Arc::new(InMemoryKeyRepository::default());
+
+            KeysHandler::new(&db_key_repository, &in_memory_key_repository)
+        }
+
+        mod with_expiring_and {
+
+            mod randomly_generated_keys {
+                use std::time::Duration;
+
+                use torrust_tracker_clock::clock::Time;
+
+                use crate::core::authentication::handler::tests::the_keys_handler_when_tracker_is_configured_as_private::instantiate_keys_handler;
+                use crate::CurrentClock;
+
+                #[tokio::test]
+                async fn it_should_generate_the_key() {
+                    let keys_handler = instantiate_keys_handler();
+
+                    let peer_key = keys_handler.generate_auth_key(Some(Duration::from_secs(100))).await.unwrap();
+
+                    assert_eq!(
+                        peer_key.valid_until,
+                        Some(CurrentClock::now_add(&Duration::from_secs(100)).unwrap())
+                    );
+                }
+            }
+
+            mod pre_generated_keys {
+                use std::time::Duration;
+
+                use torrust_tracker_clock::clock::Time;
+
+                use crate::core::authentication::handler::tests::the_keys_handler_when_tracker_is_configured_as_private::instantiate_keys_handler;
+                use crate::core::authentication::{AddKeyRequest, Key};
+                use crate::CurrentClock;
+
+                #[tokio::test]
+                async fn it_should_add_a_pre_generated_key() {
+                    let keys_handler = instantiate_keys_handler();
+
+                    let peer_key = keys_handler
+                        .add_peer_key(AddKeyRequest {
+                            opt_key: Some(Key::new("YZSl4lMZupRuOpSRC3krIKR5BPB14nrJ").unwrap().to_string()),
+                            opt_seconds_valid: Some(100),
+                        })
+                        .await
+                        .unwrap();
+
+                    assert_eq!(
+                        peer_key.valid_until,
+                        Some(CurrentClock::now_add(&Duration::from_secs(100)).unwrap())
+                    );
+                }
+            }
+        }
+
+        mod with_permanent_and {
+
+            mod randomly_generated_keys {
+                use crate::core::authentication::handler::tests::the_keys_handler_when_tracker_is_configured_as_private::instantiate_keys_handler;
+
+                #[tokio::test]
+                async fn it_should_generate_the_key() {
+                    let keys_handler = instantiate_keys_handler();
+
+                    let peer_key = keys_handler.generate_permanent_auth_key().await.unwrap();
+
+                    assert_eq!(peer_key.valid_until, None);
+                }
+            }
+
+            mod pre_generated_keys {
+
+                use crate::core::authentication::handler::tests::the_keys_handler_when_tracker_is_configured_as_private::instantiate_keys_handler;
+                use crate::core::authentication::{AddKeyRequest, Key};
+
+                #[tokio::test]
+                async fn it_should_add_a_pre_generated_key() {
+                    let keys_handler = instantiate_keys_handler();
+
+                    let peer_key = keys_handler
+                        .add_peer_key(AddKeyRequest {
+                            opt_key: Some(Key::new("YZSl4lMZupRuOpSRC3krIKR5BPB14nrJ").unwrap().to_string()),
+                            opt_seconds_valid: None,
+                        })
+                        .await
+                        .unwrap();
+
+                    assert_eq!(peer_key.valid_until, None);
+                }
+            }
+        }
+    }
+}
diff --git a/src/core/authentication/mod.rs b/src/core/authentication/mod.rs
index 86337b71..4d0001fd 100644
--- a/src/core/authentication/mod.rs
+++ b/src/core/authentication/mod.rs
@@ -221,28 +221,10 @@ mod tests {
             mod randomly_generated_keys {
                 use std::time::Duration;
 
-                use torrust_tracker_clock::clock::Time;
-
                 use crate::core::authentication::tests::the_tracker_configured_as_private::{
                     instantiate_authentication, instantiate_authentication_with_checking_keys_expiration_disabled,
                 };
                 use crate::core::authentication::Key;
-                use crate::CurrentClock;
-
-                #[tokio::test]
-                async fn it_should_generate_the_key() {
-                    let authentication = instantiate_authentication();
-
-                    let peer_key = authentication
-                        .generate_auth_key(Some(Duration::from_secs(100)))
-                        .await
-                        .unwrap();
-
-                    assert_eq!(
-                        peer_key.valid_until,
-                        Some(CurrentClock::now_add(&Duration::from_secs(100)).unwrap())
-                    );
-                }
 
                 #[tokio::test]
                 async fn it_should_authenticate_a_peer_with_the_key() {
@@ -274,33 +256,11 @@ mod tests {
             }
 
             mod pre_generated_keys {
-                use std::time::Duration;
-
-                use torrust_tracker_clock::clock::Time;
 
                 use crate::core::authentication::tests::the_tracker_configured_as_private::{
                     instantiate_authentication, instantiate_authentication_with_checking_keys_expiration_disabled,
                 };
                 use crate::core::authentication::{AddKeyRequest, Key};
-                use crate::CurrentClock;
-
-                #[tokio::test]
-                async fn it_should_add_a_pre_generated_key() {
-                    let authentication = instantiate_authentication();
-
-                    let peer_key = authentication
-                        .add_peer_key(AddKeyRequest {
-                            opt_key: Some(Key::new("YZSl4lMZupRuOpSRC3krIKR5BPB14nrJ").unwrap().to_string()),
-                            opt_seconds_valid: Some(100),
-                        })
-                        .await
-                        .unwrap();
-
-                    assert_eq!(
-                        peer_key.valid_until,
-                        Some(CurrentClock::now_add(&Duration::from_secs(100)).unwrap())
-                    );
-                }
 
                 #[tokio::test]
                 async fn it_should_authenticate_a_peer_with_the_key() {
@@ -341,15 +301,6 @@ mod tests {
             mod randomly_generated_keys {
                 use crate::core::authentication::tests::the_tracker_configured_as_private::instantiate_authentication;
 
-                #[tokio::test]
-                async fn it_should_generate_the_key() {
-                    let authentication = instantiate_authentication();
-
-                    let peer_key = authentication.generate_permanent_auth_key().await.unwrap();
-
-                    assert_eq!(peer_key.valid_until, None);
-                }
-
                 #[tokio::test]
                 async fn it_should_authenticate_a_peer_with_the_key() {
                     let authentication = instantiate_authentication();
@@ -366,21 +317,6 @@ mod tests {
                 use crate::core::authentication::tests::the_tracker_configured_as_private::instantiate_authentication;
                 use crate::core::authentication::{AddKeyRequest, Key};
 
-                #[tokio::test]
-                async fn it_should_add_a_pre_generated_key() {
-                    let authentication = instantiate_authentication();
-
-                    let peer_key = authentication
-                        .add_peer_key(AddKeyRequest {
-                            opt_key: Some(Key::new("YZSl4lMZupRuOpSRC3krIKR5BPB14nrJ").unwrap().to_string()),
-                            opt_seconds_valid: None,
-                        })
-                        .await
-                        .unwrap();
-
-                    assert_eq!(peer_key.valid_until, None);
-                }
-
                 #[tokio::test]
                 async fn it_should_authenticate_a_peer_with_the_key() {
                     let authentication = instantiate_authentication();