augmentation support for avoid_unused_constructor_parameters

Fixes: dart-lang/linter#4934


Change-Id: Iafd6ed199bf69214b6520dd56c5bd0012e029341
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/363104
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Commit-Queue: Phil Quitslund <pquitslund@google.com>

pkg/linter/lib/src/rules/avoid_unused_constructor_parameters.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';
 import '../util/ascii_utils.dart';
 
 const _desc = r'Avoid defining unused parameters in constructors.';
@@ -82,6 +83,7 @@ class _Visitor extends SimpleAstVisitor<void> {
 
   @override
   void visitConstructorDeclaration(ConstructorDeclaration node) {
+    if (node.isAugmentation) return;
     if (node.redirectedConstructor != null) return;
     if (node.externalKeyword != null) return;
 

pkg/linter/test/rules/avoid_unused_constructor_parameters_test.dart

@@ -17,6 +17,42 @@ class AvoidUnusedConstructorParametersTest extends LintRuleTest {
   @override
   String get lintRule => 'avoid_unused_constructor_parameters';
 
+  test_augmentationClass() async {
+    newFile('$testPackageLibPath/a.dart', r'''
+import augment 'test.dart';
+
+class A { }
+''');
+
+    await assertDiagnostics(r'''
+augment library 'a.dart';
+
+augment class A {
+  A(int a);
+}
+''', [
+      lint(49, 5),
+    ]);
+  }
+
+  test_augmentedConstructor() async {
+    newFile('$testPackageLibPath/a.dart', r'''
+import augment 'test.dart';
+
+class A {
+  A(int a);
+}
+''');
+
+    await assertNoDiagnostics(r'''
+augment library 'a.dart';
+
+augment class A {
+  augment A.new(int a);
+}
+''');
+  }
+
   test_super() async {
     await assertNoDiagnostics(r'''
 class A {