lamda funtion in @bot.message_handler() not working properly in telebot python

I tried to implement the following line of code in python script for a telegram bot building using telebot.

@bot.message_handler(func=lambda msg:True if msg.text.startswith('/test'))
def test_start(message):
    msg=bot.send_message(message.chat.id,'This is feature is under developement')

Above code gives me a syntax error.

@bot.message_handler(func=lambda msg:True if msg.text.startswith('/test') else False)
def test_start(message):
    msg=bot.send_message(message.chat.id,'This is feature is under developement')

This code solves the syntax error, but still, it doesn't do what I want it to do. When a user sends '/test some text' I want to identify this and do some actions after that.

I am relatively new to python and this is my first time using telebot and lambda functions. So please help me in

1. identifying why the 1st code gave me a syntax error.
2. How to implement this startswith('/test') properly. Thank you so much in advance.