PureContractClassLint class final

A lint rule requiring pure contract classes to be declared as abstract interface class.

Abstract classes that have no instance field declarations and no method bodies serve purely as interface contracts. In Dart 3+, adding the interface modifier ensures callers implement the contract rather than extending it, preventing accidental inheritance bugs.

Example

BAD:

abstract class AuthGateway {
  Future<void> signIn();
}

GOOD:

abstract interface class AuthGateway {
  Future<void> signIn();
}