pkg/linter/test/rules/prefer_final_fields_test.dart

// Copyright (c) 2022, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

import 'package:test_reflective_loader/test_reflective_loader.dart';

import '../rule_test_support.dart';

main() {
  defineReflectiveSuite(() {
    defineReflectiveTests(PreferFinalFieldsTest);
    defineReflectiveTests(PreferFinalFieldsExtensionTypesTest);
  });
}

@reflectiveTest
class PreferFinalFieldsExtensionTypesTest extends LintRuleTest {
  @override
  String get lintRule => 'prefer_final_fields';

  test_field_instance() async {
    await assertDiagnostics(r'''
extension type E(Object o) {
  int _i = 0;
}
''', [
      // No Lint.
      error(CompileTimeErrorCode.EXTENSION_TYPE_DECLARES_INSTANCE_FIELD, 35, 2),
      error(WarningCode.UNUSED_FIELD, 35, 2),
    ]);
  }

  test_field_static() async {
    await assertDiagnostics(r'''
extension type E(Object o) {
  static int _i = 0;
}
''', [
      error(WarningCode.UNUSED_FIELD, 42, 2),
      lint(42, 6),
    ]);
  }

  test_field_static_writtenInConstructor() async {
    await assertDiagnostics(r'''
extension type E(Object o) {
  static Object _o = 0;
  E.e(this.o) {
    _o = o;
  }
}
''', [
      // No lint.
      error(WarningCode.UNUSED_FIELD, 45, 2),
    ]);
  }
}

@reflectiveTest
class PreferFinalFieldsTest extends LintRuleTest {
  @override
  String get lintRule => 'prefer_final_fields';

  test_assignedInPart() async {
    newFile('$testPackageLibPath/part.dart', r'''
part of 'test.dart';
int f(C c) {
  c._x = 1;
  return c._x;
}
''');
    await assertNoDiagnostics(r'''
part 'part.dart';
class C {
  int _x = 0;
}
''');
  }

  test_declaredInPart() async {
    newFile('$testPackageLibPath/part.dart', r'''
part of 'test.dart';
class C {
  int _x = 0;
}
''');
    await assertNoDiagnostics(r'''
part 'part.dart';
int f(C c) {
  c._x = 1;
  return c._x;
}
''');
  }

  test_enum() async {
    await assertDiagnostics(r'''
enum A {
  a,b,c;
  int _x = 0;
  int get x => _x;
}
''', [
      // No Lint.
      error(CompileTimeErrorCode.NON_FINAL_FIELD_IN_ENUM, 24, 2),
    ]);
  }

  test_overrideField_extends() async {
    await assertNoDiagnostics(r'''
class A {
  bool _a = false;
  void m() {
    _a = true;
    print(_a);
  }
}

class B extends A {
  @override
  bool _a = false;

  @override
  void m() {
    print(_a);
  }
}
''');
  }

  /// https://github.com/dart-lang/linter/issues/3760
  test_overrideField_implements() async {
    await assertNoDiagnostics(r'''
class A {
  bool _a = false;
  void m() {
    _a = true;
    print(_a);
  }
}

class B implements A {
  @override
  bool _a = false;

  @override
  void m() {
    print(_a);
  }
}
''');
  }

  test_overrideSetter_extends() async {
    await assertNoDiagnostics(r'''
class A {
  set _a(bool a) {}
  void m() {
    _a = true;
  }
}

class B extends A {
  @override
  bool _a = false;

  @override
  void m() {
    print(_a);
  }
}
''');
  }

  test_overrideSetter_implements() async {
    await assertNoDiagnostics(r'''
class A {
  set _a(bool a) {}
  void m() {
    _a = true;
  }
}

class B implements A {
  @override
  bool _a = false;

  @override
  void m() {
    print(_a);
  }
}
''');
  }
}