refactor: use Username type instead of &str in TestEnvironment::initialized

Replace raw string parameter with validated Username type for better type safety
and Linux username compliance. This ensures all SSH usernames are validated
according to Linux naming requirements before being used.

- Update TestEnvironment::initialized method signature to accept &Username
- Update all calling sites to create Username instances before calling
- Update documentation examples to show proper Username usage
- Maintain backward compatibility by using the same 'torrust' username

Author: josecelano

src/bin/e2e_config_tests.rs

@@ -51,6 +51,7 @@ use torrust_tracker_deploy::e2e::tasks::run_configure_command::run_configure_com
 use tracing::{error, info};
 
 use torrust_tracker_deploy::config::InstanceName;
+use torrust_tracker_deploy::domain::Username;
 use torrust_tracker_deploy::e2e::environment::{TestEnvironment, TestEnvironmentType};
 use torrust_tracker_deploy::e2e::tasks::{
     container::{
@@ -114,10 +115,12 @@ pub async fn main() -> Result<()> {
     let instance_name =
         InstanceName::new("torrust-tracker-vm".to_string()).expect("Valid hardcoded instance name");
 
+    let ssh_user = Username::new("torrust").expect("Valid hardcoded username");
+
     let env = TestEnvironment::initialized(
         false,
         cli.templates_dir,
-        "torrust",
+        &ssh_user,
         instance_name,
         TestEnvironmentType::Container,
     )?;

src/bin/e2e_provision_tests.rs

@@ -23,6 +23,7 @@ use tracing::{error, info};
 
 // Import E2E testing infrastructure
 use torrust_tracker_deploy::config::InstanceName;
+use torrust_tracker_deploy::domain::Username;
 use torrust_tracker_deploy::e2e::environment::{TestEnvironment, TestEnvironmentType};
 use torrust_tracker_deploy::e2e::tasks::{
     preflight_cleanup::cleanup_lingering_resources,
@@ -98,10 +99,12 @@ pub async fn main() -> Result<()> {
     let instance_name =
         InstanceName::new("torrust-tracker-vm".to_string()).expect("Valid hardcoded instance name");
 
+    let ssh_user = Username::new("torrust").expect("Valid hardcoded username");
+
     let env = TestEnvironment::initialized(
         cli.keep,
         cli.templates_dir,
-        "torrust",
+        &ssh_user,
         instance_name,
         TestEnvironmentType::VirtualMachine,
     )?;

src/bin/e2e_tests_full.rs

@@ -28,6 +28,7 @@ use tracing::{error, info};
 
 // Import E2E testing infrastructure
 use torrust_tracker_deploy::config::InstanceName;
+use torrust_tracker_deploy::domain::Username;
 use torrust_tracker_deploy::e2e::environment::{TestEnvironment, TestEnvironmentType};
 use torrust_tracker_deploy::e2e::tasks::{
     preflight_cleanup::cleanup_lingering_resources,
@@ -97,10 +98,12 @@ pub async fn main() -> Result<()> {
     let instance_name =
         InstanceName::new("torrust-tracker-vm".to_string()).expect("Valid hardcoded instance name");
 
+    let ssh_user = Username::new("torrust").expect("Valid hardcoded username");
+
     let env = TestEnvironment::initialized(
         cli.keep,
         cli.templates_dir,
-        "torrust",
+        &ssh_user,
         instance_name,
         TestEnvironmentType::VirtualMachine,
     )?;

src/e2e/environment.rs

@@ -26,6 +26,7 @@ use tracing::{info, warn};
 
 use crate::config::{Config, InstanceName, SshCredentials};
 use crate::container::Services;
+use crate::domain::Username;
 
 /// Errors that can occur during test environment creation and initialization
 #[derive(Debug, thiserror::Error)]
@@ -109,7 +110,7 @@ impl TestEnvironment {
     pub fn initialized(
         keep_env: bool,
         templates_dir: impl Into<std::path::PathBuf>,
-        ssh_user: &str,
+        ssh_user: &Username,
         instance_name: InstanceName,
         environment_type: TestEnvironmentType,
     ) -> Result<Self, TestEnvironmentError> {
@@ -189,7 +190,7 @@ impl TestEnvironment {
     fn setup_ssh_credentials(
         project_root: &std::path::Path,
         temp_dir: &TempDir,
-        ssh_user: &str,
+        ssh_user: &Username,
     ) -> Result<SshCredentials, TestEnvironmentError> {
         let temp_ssh_key = temp_dir.path().join(SSH_PRIVATE_KEY_FILENAME);
         let temp_ssh_pub_key = temp_dir.path().join(SSH_PUBLIC_KEY_FILENAME);

src/e2e/tasks/container/run_provision_simulation.rs

@@ -64,14 +64,16 @@ use crate::infrastructure::ansible::AnsibleTemplateRenderer;
 /// use torrust_tracker_deploy::e2e::tasks::container::run_provision_simulation::run_provision_simulation;
 /// use torrust_tracker_deploy::e2e::environment::{TestEnvironment, TestEnvironmentType};
 /// use torrust_tracker_deploy::config::InstanceName;
+/// use torrust_tracker_deploy::domain::Username;
 ///
 /// #[tokio::main]
 /// async fn main() -> anyhow::Result<()> {
 ///     let instance_name = InstanceName::new("test-container".to_string())?;
+///     let ssh_user = Username::new("torrust")?;
 ///     let test_env = TestEnvironment::initialized(
 ///         false,
 ///         "./templates".to_string(),
-///         "torrust",
+///         &ssh_user,
 ///         instance_name,
 ///         TestEnvironmentType::Container
 ///     )?;