feat: add wrap with observer assist

mobx_lint/CHANGELOG.md

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+## 1.0.0
+
+- add wrap with observer assist by [@amondnet](https://github.com/amondnet)

mobx_lint/LICENSE

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+MIT License
+
+Copyright (c) 2018 MobX
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

mobx_lint/README.md

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+mobx_lint is a developer tool for users of mobx, designed to help stop common issues and simplify repetitive tasks.
+
+mobx_lint adds various warnings with quick fixes and refactoring options, such as:
+
+- Refactor wrap a widget with Observer
+
+## Installing mobx_lint
+
+mobx_lint is implemented using [custom_lint]. As such, it uses custom_lint's installation logic.  
+Long story short:
+
+- Add both mobx_lint and custom_lint to your `pubspec.yaml`:
+  ```yaml
+  dev_dependencies:
+    custom_lint:
+    mobx_lint:
+  ```
+- Enable `custom_lint`'s plugin in your `analysis_options.yaml`:
+
+  ```yaml
+  analyzer:
+    plugins:
+      - custom_lint
+  ```
+
+## Running mobx_lint in the terminal/CI
+
+Custom lint rules created by mobx_lint may not show-up in `dart analyze`.
+To fix this, you can run a custom command line: `custom_lint`.
+
+Since your project should already have custom_lint installed
+(cf [installing mobx_lint](#installing-mobx_lint)), then you should be
+able to run:
+
+```sh
+dart run custom_lint
+```
+
+Alternatively, you can globally install `custom_lint`:
+
+```sh
+# Install custom_lint for all projects
+dart pub global activate custom_lint
+# run custom_lint's command line in a project
+custom_lint
+```
+
+## All assists
+
+### Wrap widgets with a `Consumer`
+
+![Wrap with Consumer sample](resources/wrap_with_observer.gif)

mobx_lint/analysis_options.yaml

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+# This file configures the static analysis results for your project (errors,
+# warnings, and lints).
+#
+# This enables the 'recommended' set of lints from `package:lints`.
+# This set helps identify many issues that may lead to problems when running
+# or consuming Dart code, and enforces writing Dart using a single, idiomatic
+# style and format.
+#
+# If you want a smaller set of lints you can change this to specify
+# 'package:lints/core.yaml'. These are just the most critical lints
+# (the recommended set includes the core lints).
+# The core lints are also what is used by pub.dev for scoring packages.
+
+include: package:lints/recommended.yaml
+
+# Uncomment the following section to specify additional rules.
+
+# linter:
+#   rules:
+#     - camel_case_types
+
+# analyzer:
+#   exclude:
+#     - path/to/excluded/files/**
+
+# For more information about the core and recommended set of lints, see
+# https://dart.dev/go/core-lints
+
+# For additional information about configuring this file, see
+# https://dart.dev/guides/language/analysis-options

mobx_lint/lib/mobx_lint.dart

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+library mobx_lint;
+
+import 'package:custom_lint_builder/custom_lint_builder.dart';
+
+import 'src/assists/wrap_with_observer.dart';
+
+PluginBase createPlugin() => _MobxPlugin();
+
+class _MobxPlugin extends PluginBase {
+  @override
+  List<LintRule> getLintRules(CustomLintConfigs configs) => [];
+
+  @override
+  List<Assist> getAssists() => [
+        WrapWithObserver(),
+      ];
+}

mobx_lint/lib/src/assists/wrap_with_observer.dart

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+import 'package:analyzer/source/source_range.dart';
+import 'package:custom_lint_builder/custom_lint_builder.dart';
+import 'package:mobx_lint/src/mobx_custom_lint.dart';
+
+import '../mobx_types.dart';
+
+/// Right above "wrap in builder"
+const wrapPriority = 28;
+
+class WrapWithObserver extends MobxAssist {
+  WrapWithObserver();
+
+  @override
+  void run(
+    CustomLintResolver resolver,
+    ChangeReporter reporter,
+    CustomLintContext context,
+    SourceRange target,
+  ) {
+    context.registry.addInstanceCreationExpression((node) {
+      // Select from "new" to the opening bracket
+      if (!target.intersects(node.constructorName.sourceRange)) return;
+
+      final createdType = node.constructorName.type.type;
+
+      if (createdType == null ||
+          !widgetType.isAssignableFromType(createdType)) {
+        return;
+      }
+
+      final changeBuilder = reporter.createChangeBuilder(
+        message: 'Wrap with Observer',
+        priority: wrapPriority,
+      );
+
+      changeBuilder.addDartFileEdit((builder) {
+        builder.addSimpleInsertion(
+          node.offset,
+          'Observer(builder: (context) { return ',
+        );
+        builder.addSimpleInsertion(node.end, '; },)');
+      });
+    });
+  }
+}

mobx_lint/lib/src/mobx_custom_lint.dart

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+import 'package:analyzer/source/source_range.dart';
+import 'package:custom_lint_builder/custom_lint_builder.dart';
+
+abstract class MobxAssist extends DartAssist {
+  @override
+  Future<void> startUp(
+    CustomLintResolver resolver,
+    CustomLintContext context,
+    SourceRange target,
+  ) async {
+    await super.startUp(resolver, context, target);
+  }
+}

mobx_lint/lib/src/mobx_types.dart

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+import 'package:custom_lint_builder/custom_lint_builder.dart';
+
+/// [TypeChecker] from `Widget` from Flutter
+const widgetType = TypeChecker.fromName('Widget', packageName: 'flutter');

mobx_lint/pubspec.yaml

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+name: mobx_lint
+description: A starting point for Dart libraries or applications.
+version: 1.0.0
+# repository: https://github.com/my_org/my_repo
+
+environment:
+  sdk: ">=2.16.0 <3.0.0"
+
+dependencies:
+  analyzer: ">=6.0.0 <7.0.0"
+  analyzer_plugin: ^0.11.2
+  collection: ^1.16.0
+  custom_lint_builder: ^0.5.2
+  meta: ^1.7.0
+  path: ^1.8.1
+  mobx: ^2.2.0
+dev_dependencies:
+  lints: ^2.0.0
+  test: ^1.21.0