nixpkgs/nixos/tests/mailhog.nix

import ./make-test-python.nix (
  { lib, ... }:
  {
    name = "mailhog";
    meta.maintainers = with lib.maintainers; [
      jojosch
      RTUnreal
    ];

    nodes.machine =
      { pkgs, ... }:
      {
        services.mailhog.enable = true;
      };

    testScript = ''
      start_all()

      machine.wait_for_unit("mailhog.service")
      machine.wait_for_open_port(1025)
      machine.wait_for_open_port(8025)
      # Test sendmail wrapper (this uses smtp, which tests the connection)
      machine.succeed('printf "To: root@example.com\r\n\r\nthis is the body of the email" | sendmail -f sender@example.com')
      res = machine.succeed(
          "curl --fail http://localhost:8025/api/v2/messages"
      )
      assert all(msg in res for msg in ["this is the body of the email", "sender@example.com", "root@example.com"])
    '';
  }
)