don't camel_case lint augmented extensions

Fixes: https://github.com/dart-lang/linter/issues/4898

Change-Id: I4c4836bc650eb6f5888fde739e1bfcf5858ce9f4
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/361123
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Commit-Queue: Phil Quitslund <pquitslund@google.com>
diff --git a/pkg/linter/lib/src/rules/camel_case_extensions.dart b/pkg/linter/lib/src/rules/camel_case_extensions.dart
index c43a451..36fd6b2 100644
--- a/pkg/linter/lib/src/rules/camel_case_extensions.dart
+++ b/pkg/linter/lib/src/rules/camel_case_extensions.dart
@@ -61,7 +61,9 @@
 
   @override
   void visitExtensionDeclaration(ExtensionDeclaration node) {
-    // TODO(pq): don't lint augmentations, https://github.com/dart-lang/linter/issues/4898
+    // Don't lint augmentations.
+    if (node.augmentKeyword != null) return;
+
     var name = node.name;
     if (name != null && !isCamelCase(name.lexeme)) {
       rule.reportLintForToken(name, arguments: [name.lexeme]);
diff --git a/pkg/linter/test/rules/camel_case_extensions_test.dart b/pkg/linter/test/rules/camel_case_extensions_test.dart
index 7e59fb5..4eb5e89 100644
--- a/pkg/linter/test/rules/camel_case_extensions_test.dart
+++ b/pkg/linter/test/rules/camel_case_extensions_test.dart
@@ -17,10 +17,6 @@
   @override
   String get lintRule => 'camel_case_extensions';
 
-  @FailingTest(
-      issue: 'https://github.com/dart-lang/linter/issues/4898',
-      reason:
-          "ParserErrorCode.EXTRANEOUS_MODIFIER [27, 7, Can't have modifier 'augment' here.]")
   test_augmentationExtension_lowerCase() async {
     newFile('$testPackageLibPath/a.dart', r'''
 import augment 'test.dart';