what is a smoke test for software code example

Example 1: what is smoke testing

Smoke tests are basic tests that check basic 
functionality of the application. 
They are meant to be quick to execute, and
their goal is to give you the assurance
that the major features of your system 
are working as expected.
• Smoke tests can be useful right after
a new build is made to decide whether or 
not you can run more expensive tests, or
right after a deployment to make sure 
that they application is running properly
in the newly deployed environment.

Example 2: failure rate in smoke test

How often do your smoke test fail?

it does not fail, the rate of fails very very low
not functionality reason
failure rate is very low
%99 due to system issue, network issue.