[DAS] Adds tests for enum defaults to handle private declarations

Bug: #61873
Change-Id: I118d5a4b013d8b962fa9fe10a6e1de326e2ae0fb
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/459760
Auto-Submit: Felipe Morschel <git@fmorschel.dev>
Commit-Queue: Paul Berry <paulberry@google.com>
Reviewed-by: Samuel Rawlins <srawlins@google.com>
Reviewed-by: Paul Berry <paulberry@google.com>

Author: FMorschel

pkg/analysis_server/test/src/services/correction/fix/add_missing_switch_cases_test.dart

@@ -358,6 +358,60 @@ int f(num x) {
 ''');
   }
 
+  Future<void> test_privateEnum() async {
+    newFile('$testPackageLibPath/enum.dart', r'''
+enum _E { first, second }
+
+_E f() => _E.first;
+''');
+    await resolveTestCode('''
+import 'enum.dart';
+
+int g() {
+  return switch (f()) {
+  };
+}
+''');
+    await assertHasFix('''
+import 'enum.dart';
+
+int g() {
+  return switch (f()) {
+    // TODO: Handle this case.
+    _ => throw UnimplementedError(),
+  };
+}
+''');
+  }
+
+  Future<void> test_privateEnumConstant() async {
+    newFile('$testPackageLibPath/enum.dart', r'''
+enum E { first, second, _unknown }
+''');
+    await resolveTestCode('''
+import 'enum.dart';
+
+int g(E e) {
+  return switch (e) {
+  };
+}
+''');
+    await assertHasFix('''
+import 'enum.dart';
+
+int g(E e) {
+  return switch (e) {
+    // TODO: Handle this case.
+    E.first => throw UnimplementedError(),
+    // TODO: Handle this case.
+    E.second => throw UnimplementedError(),
+    // TODO: Handle this case.
+    _ => throw UnimplementedError(),
+  };
+}
+''');
+  }
+
   Future<void> test_sealed_impl() async {
     var otherRoot = getFolder('$packagesRootPath/other');
     newFile('$otherRoot/lib/src/private.dart', '''
@@ -884,6 +938,64 @@ void f(num x) {
 ''');
   }
 
+  Future<void> test_privateEnum() async {
+    newFile('$testPackageLibPath/enum.dart', r'''
+enum _E { first, second }
+
+_E f() => _E.first;
+''');
+    await resolveTestCode('''
+import 'enum.dart';
+
+int g() {
+  switch (f()) {
+  }
+}
+''');
+    await assertHasFix('''
+import 'enum.dart';
+
+int g() {
+  switch (f()) {
+    default:
+      // TODO: Handle this case.
+      throw UnimplementedError();
+  }
+}
+''');
+  }
+
+  Future<void> test_privateEnumConstant() async {
+    newFile('$testPackageLibPath/enum.dart', r'''
+enum E { first, second, _unknown }
+''');
+    await resolveTestCode('''
+import 'enum.dart';
+
+int g(E e) {
+  switch (e) {
+  }
+}
+''');
+    await assertHasFix('''
+import 'enum.dart';
+
+int g(E e) {
+  switch (e) {
+    case E.first:
+      // TODO: Handle this case.
+      throw UnimplementedError();
+    case E.second:
+      // TODO: Handle this case.
+      throw UnimplementedError();
+    default:
+      // TODO: Handle this case.
+      throw UnimplementedError();
+  }
+}
+''');
+  }
+
   Future<void> test_static() async {
     await resolveTestCode('''
 enum E {