augmentation support for prefer_typing_uninitialized_variables

Fixes: https://github.com/dart-lang/linter/issues/4954

Change-Id: I66726265b1f016ed1d2d4574d781d9b3622a1ad3
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/364200
Reviewed-by: Brian Wilkerson <[email protected]>
Commit-Queue: Phil Quitslund <[email protected]>

Author: pq

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

@@ -6,6 +6,7 @@ import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/visitor.dart';
 
 import '../analyzer.dart';
+import '../extensions.dart';
 
 const _desc = r'Prefer typing uninitialized variables and fields.';
 
@@ -88,16 +89,13 @@ class _Visitor extends SimpleAstVisitor<void> {
 
   @override
   void visitVariableDeclarationList(VariableDeclarationList node) {
-    if (node.type != null) {
-      return;
-    }
-
-    var code = node.parent is FieldDeclaration
-        ? PreferTypingUninitializedVariables.forField
-        : PreferTypingUninitializedVariables.forVariable;
+    if (node.type != null) return;
 
     for (var v in node.variables) {
-      if (v.initializer == null) {
+      if (v.initializer == null && !v.isAugmentation) {
+        var code = node.parent is FieldDeclaration
+            ? PreferTypingUninitializedVariables.forField
+            : PreferTypingUninitializedVariables.forVariable;
         rule.reportLint(v, errorCode: code);
       }
     }

pkg/linter/test/rules/prefer_typing_uninitialized_variables_test.dart

@@ -17,6 +17,32 @@ class PreferTypingUninitializedVariablesTest extends LintRuleTest {
   @override
   String get lintRule => 'prefer_typing_uninitialized_variables';
 
+  test_field_augmented() async {
+    var a = newFile('$testPackageLibPath/a.dart', r'''
+import augment 'b.dart';
+
+class A {
+  var x;
+}
+''');
+
+    var b = newFile('$testPackageLibPath/b.dart', r'''
+augment library 'a.dart';
+
+augment class A {
+  augment var x;
+}
+''');
+
+    result = await resolveFile(a.path);
+    await assertDiagnosticsIn(errors, [
+      lint(42, 1),
+    ]);
+
+    result = await resolveFile(b.path);
+    await assertNoDiagnosticsIn(errors);
+  }
+
   test_field_final_noInitializer() async {
     await assertDiagnostics(r'''
 class C {
@@ -105,6 +131,28 @@ void f() {
     ]);
   }
 
+  test_topLevelVariable_augmented() async {
+    var a = newFile('$testPackageLibPath/a.dart', r'''
+import augment 'b.dart';
+
+var x;
+''');
+
+    var b = newFile('$testPackageLibPath/b.dart', r'''
+augment library 'a.dart';
+
+augment var x;
+''');
+
+    result = await resolveFile(a.path);
+    await assertDiagnosticsIn(errors, [
+      lint(30, 1),
+    ]);
+
+    result = await resolveFile(b.path);
+    await assertNoDiagnosticsIn(errors);
+  }
+
   test_topLevelVariable_var_initializer() async {
     await assertNoDiagnostics(r'''
 var x = 4;