test: add tests for smtp mailer config

lib/mv/config.ex

@@ -449,4 +449,42 @@ defmodule Mv.Config do
   def oidc_admin_group_name_env_set?, do: env_set?("OIDC_ADMIN_GROUP_NAME")
   def oidc_groups_claim_env_set?, do: env_set?("OIDC_GROUPS_CLAIM")
   def oidc_only_env_set?, do: env_set?("OIDC_ONLY")
+
+  # ---------------------------------------------------------------------------
+  # SMTP configuration (stubs for TDD – ENV overrides Settings; see docs/smtp-configuration-concept.md)
+  # ---------------------------------------------------------------------------
+
+  @doc "Returns SMTP host. ENV SMTP_HOST overrides Settings. Stub: always nil until implemented."
+  @spec smtp_host() :: String.t() | nil
+  def smtp_host, do: nil
+
+  @doc "Returns SMTP port (e.g. 587). ENV SMTP_PORT overrides Settings. Stub: always nil until implemented."
+  @spec smtp_port() :: non_neg_integer() | nil
+  def smtp_port, do: nil
+
+  @doc "Returns SMTP username. ENV SMTP_USERNAME overrides Settings. Stub: always nil until implemented."
+  @spec smtp_username() :: String.t() | nil
+  def smtp_username, do: nil
+
+  @doc "Returns SMTP password. ENV SMTP_PASSWORD overrides SMTP_PASSWORD_FILE overrides Settings. Stub: always nil until implemented."
+  @spec smtp_password() :: String.t() | nil
+  def smtp_password, do: nil
+
+  @doc "Returns SMTP TLS/SSL mode (e.g. 'tls', 'ssl', 'none'). Stub: always nil until implemented."
+  @spec smtp_ssl() :: String.t() | nil
+  def smtp_ssl, do: nil
+
+  @doc "Returns true when SMTP is configured (e.g. host present). Stub: always false until implemented."
+  @spec smtp_configured?() :: boolean()
+  def smtp_configured?, do: false
+
+  @doc "Returns true when any SMTP ENV variable is set (for Settings UI hint). Stub: always false until implemented."
+  @spec smtp_env_configured?() :: boolean()
+  def smtp_env_configured?, do: false
+
+  def smtp_host_env_set?, do: env_set?("SMTP_HOST")
+  def smtp_port_env_set?, do: env_set?("SMTP_PORT")
+  def smtp_username_env_set?, do: env_set?("SMTP_USERNAME")
+  def smtp_password_env_set?, do: env_set?("SMTP_PASSWORD") or env_set?("SMTP_PASSWORD_FILE")
+  def smtp_ssl_env_set?, do: env_set?("SMTP_SSL")
 end

lib/mv/mailer.ex

@@ -16,4 +16,15 @@ defmodule Mv.Mailer do
   def mail_from do
     Application.get_env(:mv, :mail_from, {"Mila", "noreply@example.com"})
   end
+
+  @doc """
+  Sends a test email to the given address. Used from Global Settings SMTP section.
+
+  Returns `{:ok, email}` on success, `{:error, reason}` on failure (e.g. invalid address,
+  SMTP not configured, connection error). Stub: always returns error until implemented.
+  """
+  @spec send_test_email(String.t()) :: {:ok, Swoosh.Email.t()} | {:error, term()}
+  def send_test_email(_to_email) do
+    {:error, :not_implemented}
+  end
 end