How to enable assertions in dart?

Question

here is an excerpt from my code containing the assertion

assert(age<30,'age must be less than 30');                             

Now, How to enable this assertion?

Answer 1

Use the --enable-asserts flag:

dart --enable-asserts file_name.dart

Answer 2

assert s are enabled in debug builds of Flutter apps. They are not enabled in release builds.

If you need to check conditions in release builds, assert s are inappropriate: assert s are intended as sanity-checks to identify logical errors (ie, mistakes in the code), not to catch runtime errors (eg unexpected input from the users).

Also see: why the assert function was disabled in dart?