How to use the mailmerge.utils.MailmergeError function in mailmerge

def test_attachment_tilde_path(tmpdir):
    """Attachment with home directory tilde notation file path."""
    template_path = Path(tmpdir/"template.txt")
    template_path.write_text(textwrap.dedent(u"""\
        TO: to@test.com
        FROM: from@test.com
        ATTACHMENT: ~/attachment.txt

        Hello world
    """))

    # Render will throw an error because we didn't create a file in the
    # user's home directory.  We'll just check the filename.
    template_message = TemplateMessage(template_path)
    with pytest.raises(MailmergeError) as err:
        template_message.render({})
    correct_path = Path.home() / "attachment.txt"
    assert str(correct_path) in str(err)

def test_attachment_not_found(tmpdir):
    """Attachment file not found."""
    # Template specifying an attachment that doesn't exist
    template_path = Path(tmpdir/"template.txt")
    template_path.write_text(textwrap.dedent(u"""\
        TO: to@test.com
        FROM: from@test.com
        ATTACHMENT: attachment.txt

        Hello world
    """))

    # Render in tmpdir, which lacks attachment.txt
    template_message = TemplateMessage(template_path)
    with pytest.raises(MailmergeError):
        with tmpdir.as_cwd():
            template_message.render({})

except jinja2.exceptions.TemplateError as err:
        sys.exit(">>> Error in Jinja2 template: {}".format(err))
    except csv.Error as err:
        sys.exit(">>> Error reading CSV file: {}".format(err))
    except smtplib.SMTPAuthenticationError as err:
        sys.exit(">>> Authentication error: {}".format(err))
    except configparser.Error as err:
        sys.exit(
            ">>> Error reading config file {filename}: {message}"
            .format(filename=config_path, message=err)
        )
    except smtplib.SMTPException as err:
        sys.exit(">>> Error sending message", err, sep=' ', file=sys.stderr)
    except socket.error:
        sys.exit(">>> Error connecting to server")
    except MailmergeError as err:
        sys.exit(">>> {}".format(err))

    # Hints for user
    if not no_limit:
        print(
            ">>> Limit was {limit} message{pluralizer}.  "
            "To remove the limit, use the --no-limit option."
            .format(limit=limit, pluralizer=("" if limit == 1 else "s"))
        )
    if dry_run:
        print(
            ">>> This was a dry run.  "
            "To send messages, use the --no-dry-run option."