augmentation support for avoid_classes_with_only_static_members

Fixes: https://github.com/dart-lang/linter/issues/4931


Change-Id: I4194dd6e4d8790998b202bdb654b9a9d7a114104
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/363422
Reviewed-by: Brian Wilkerson <[email protected]>
Commit-Queue: Phil Quitslund <[email protected]>

Author: pq

pkg/linter/lib/src/rules/avoid_classes_with_only_static_members.dart

@@ -7,6 +7,7 @@ import 'package:analyzer/dart/ast/visitor.dart';
 import 'package:analyzer/dart/element/element.dart';
 
 import '../analyzer.dart';
+import '../extensions.dart';
 
 const _desc = r'Avoid defining a class that contains only static members.';
 
@@ -43,18 +44,6 @@ const _favoriteMammal = 'weasel';
 
 ''';
 
-bool _isNonConst(FieldElement element) => !element.isConst;
-
-bool _isStaticMember(ClassMember classMember) {
-  if (classMember is MethodDeclaration) {
-    return classMember.isStatic;
-  }
-  if (classMember is FieldDeclaration) {
-    return classMember.isStatic;
-  }
-  return false;
-}
-
 class AvoidClassesWithOnlyStaticMembers extends LintRule {
   static const LintCode code = LintCode(
       'avoid_classes_with_only_static_members',
@@ -103,9 +92,20 @@ class _Visitor extends SimpleAstVisitor<void> {
       }
     }
 
-    if (node.members.isNotEmpty &&
-        node.members.every(_isStaticMember) &&
-        (element.methods.isNotEmpty || element.fields.any(_isNonConst))) {
+    var declaredElement = node.declaredElement;
+    if (declaredElement == null) return;
+
+    var constructors = declaredElement.allConstructors;
+    if (constructors.isNotEmpty &&
+        constructors.any((c) => !c.isDefaultConstructor)) {
+      return;
+    }
+
+    var methods = declaredElement.allMethods;
+    if (methods.isNotEmpty && !methods.every((m) => m.isStatic)) return;
+
+    if (methods.isNotEmpty ||
+        declaredElement.allFields.any((f) => !f.isConst)) {
       rule.reportLint(node);
     }
   }

pkg/linter/test/rules/avoid_classes_with_only_static_members_test.dart

@@ -17,6 +17,79 @@ class AvoidClassesWithOnlyStaticMembers extends LintRuleTest {
   @override
   String get lintRule => 'avoid_classes_with_only_static_members';
 
+  test_augmentationClass_nonStaticField() async {
+    var a = newFile('$testPackageLibPath/a.dart', r'''
+import augment 'b.dart';
+
+class A {
+  static int f = 1;
+}
+''');
+
+    // The added field should prevent a lint above.
+    var b = newFile('$testPackageLibPath/b.dart', r'''
+augment library 'a.dart';
+
+augment class A { 
+  int a = 1;
+}
+''');
+
+    result = await resolveFile(a.path);
+    await assertNoDiagnosticsIn(errors);
+
+    result = await resolveFile(b.path);
+    await assertNoDiagnosticsIn(errors);
+  }
+
+  test_augmentationClass_staticField() async {
+    var a = newFile('$testPackageLibPath/a.dart', r'''
+import augment 'b.dart';
+
+class A {}
+''');
+
+    var b = newFile('$testPackageLibPath/b.dart', r'''
+augment library 'a.dart';
+
+augment class A { 
+  static int f = 1;
+}
+''');
+
+    result = await resolveFile(a.path);
+    await assertDiagnosticsIn(errors, [
+      lint(26, 10),
+    ]);
+
+    result = await resolveFile(b.path);
+    await assertNoDiagnosticsIn(errors);
+  }
+
+  test_augmentationClass_staticMethod() async {
+    var a = newFile('$testPackageLibPath/a.dart', r'''
+import augment 'b.dart';
+
+class A {}
+''');
+
+    var b = newFile('$testPackageLibPath/b.dart', r'''
+augment library 'a.dart';
+
+augment class A { 
+  static void m() {}
+}
+''');
+
+    result = await resolveFile(a.path);
+    await assertDiagnosticsIn(errors, [
+      lint(26, 10),
+    ]);
+
+    result = await resolveFile(b.path);
+    await assertNoDiagnosticsIn(errors);
+  }
+
   test_basicClass() async {
     await assertDiagnostics(r'''
 class C {