exhaustive_cases

Details
Usage

Define case clauses for all constants in enum-like classes.

This rule is available as of Dart 2.9.0.

Rule sets: recommended, flutter

This rule has a quick fix available.

Details

Switching on instances of enum-like classes should be exhaustive.

Enum-like classes are defined as concrete (non-abstract) classes that have:

only private non-factory constructors
two or more static const fields whose type is the enclosing class and
no subclasses of the class in the defining library

DO define case clauses for all constants in enum-like classes.

BAD:

class EnumLike {
  final int i;
  const EnumLike._(this.i);

  static const e = EnumLike._(1);
  static const f = EnumLike._(2);
  static const g = EnumLike._(3);
}

void bad(EnumLike e) {
  // Missing case.
  switch(e) { // LINT
    case EnumLike.e :
      print('e');
      break;
    case EnumLike.f :
      print('f');
      break;
  }
}

GOOD:

class EnumLike {
  final int i;
  const EnumLike._(this.i);

  static const e = EnumLike._(1);
  static const f = EnumLike._(2);
  static const g = EnumLike._(3);
}

void ok(EnumLike e) {
  // All cases covered.
  switch(e) { // OK
    case EnumLike.e :
      print('e');
      break;
    case EnumLike.f :
      print('f');
      break;
    case EnumLike.g :
      print('g');
      break;
  }
}

Usage

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

linter:
  rules:
    - exhaustive_cases