contains<E> static method

Rule<String, E> contains<E>(String substring, { required E error, })

Validates that the string contains substring.

StringRules.contains('@', error: 'Must contain @')

Implementation

static Rule<String, E> contains<E>(String substring, {required E error}) =>
    PredicateRule(
      predicate: (value) => value.contains(substring),
      error: error,
    );