prefer_bool_in_asserts

Prefer using a boolean as the assert condition.

NOTE: This rule is removed in Dart 3.0.0; it is no longer functional.

DO use a boolean for assert conditions.

Not using booleans in assert conditions can lead to code where it isn't clear what the intention of the assert statement is.

BAD:

assert(() {
  f();
  return true;
});

GOOD:

assert(() {
  f();
  return true;
}());

To enable the prefer_bool_in_asserts rule, add prefer_bool_in_asserts under linter > rules in your analysis_options.yaml file:

linter:
  rules:
    - prefer_bool_in_asserts

If you're instead using the YAML map syntax to configure linter rules, add prefer_bool_in_asserts: true under linter > rules:

linter:
  rules:
    prefer_bool_in_asserts: true

Unless stated otherwise, the documentation on this site reflects Dart 3.6.0. Page last updated on 2025-01-27. View source or report an issue.