arch_guard_lint 0.2.0

Analyzer plugin that shows arch_guard layer violations, forbidden package imports and circular dependencies as warnings in your IDE and in dart analyze, with quick fixes.

example/README.md

arch_guard_lint example

A small app whose domain layer must not depend on data or on dart:io, and whose files must not import each other in a cycle. With the plugin enabled, all three mistakes show up as warnings in the IDE and in dart analyze, each with a quick fix.

1. Enable the plugin

# analysis_options.yaml
plugins:
  arch_guard_lint: ^0.2.0

Restart the Dart analysis server after changing plugins:.

2. Describe the architecture

# arch_guard.yaml
layers:
  domain:
    patterns: ["lib/domain/**"]
    forbidden_packages: ["dart:io"]
  data:
    patterns: ["lib/data/**"]
    allowed_imports: [domain]

3. Write code that breaks the rules

// lib/data/user_repository.dart
class UserRepository {}

// lib/domain/user_service.dart
import 'dart:io'; // the domain layer may not use dart:io
import '../data/user_repository.dart'; // domain may not import data
import 'user.dart';

class UserService {
  UserService(this.repository);

  final UserRepository repository;
  User? current;

  bool get cacheExists => File('cache.json').existsSync();
}

// lib/domain/user.dart
import 'user_service.dart'; // closes a cycle: user_service -> user -> user_service

class User {
  UserService? service;
}

4. See the warnings

$ dart analyze
warning - lib/domain/user.dart:1:8 - This import closes a circular dependency of 2 files: lib/domain/user_service.dart -> lib/domain/user.dart -> lib/domain/user_service.dart. Removing it breaks the cycle. Move the code both files need into a third file, or invert the dependency. - circular_dependency
warning - lib/domain/user_service.dart:1:8 - Layer `domain` may not import `dart:io` (forbidden_packages: `dart:io`). Depend on an interface declared in `domain` and implement it in a layer that may use `dart:io`, or, if this is intended, remove `dart:io` from the `forbidden_packages` of `domain`. - forbidden_package
warning - lib/domain/user_service.dart:2:8 - Layer `domain` imports `lib/data/user_repository.dart` from layer `data`. `domain` may not import other layers. Invert the dependency (e.g. an interface in `domain` that `data` implements), move the code to a layer `domain` may import, or, if this dependency is intended, add `data` to the `allowed_imports` of `domain`. - layer_violation

5. Fix them from the IDE

Open the quick-fix menu on a warning (VS Code: Ctrl+. / Cmd+.):

• Remove this import works on all three warnings.
• Allow layer domain to import data (arch_guard.yaml) works on the layer_violation. It adds data to domain's allowed_imports:

  domain:
    patterns: ["lib/domain/**"]
    forbidden_packages: ["dart:io"]
    allowed_imports: [data]

To accept one on purpose, add // ignore: arch_guard_lint/layer_violation above the import. To accept everything that exists today, run dart run arch_guard --update-baseline: the plugin skips problems listed in arch_guard_baseline.json.