[analysis_server] Preserve field doc comments in CONVERT_CLASS_TO_ENU…

…M assist

Fixes #53202

Bug: #53202
Change-Id: Icbc1627da55eb7c680cba802fdb931a843317b3d
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/336860
Commit-Queue: Phil Quitslund <pquitslund@google.com>
Auto-Submit: Parker Lougheed <parlough@gmail.com>
Reviewed-by: Phil Quitslund <pquitslund@google.com>
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>

pkg/analysis_server/lib/src/services/correction/dart/convert_class_to_enum.dart

@@ -194,8 +194,20 @@ class _EnumDescription {
         .sort((first, second) => first.indexValue.compareTo(second.indexValue));
     for (var field in fieldsToConvert) {
       // Compute the declaration of the corresponding enum constant.
+      var documentationComment = field.element.documentationComment;
       if (constantsBuffer.isNotEmpty) {
-        constantsBuffer.write(',$eol$indent');
+        constantsBuffer.write(',$eol');
+        if (documentationComment != null) {
+          // If the current field has a documentation comment and
+          // it's not the first field, add an extra new line.
+          constantsBuffer.write(eol);
+        }
+        constantsBuffer.write(indent);
+      }
+      if (documentationComment != null) {
+        constantsBuffer
+            .write(documentationComment.replaceAll(eol, '$eol$indent'));
+        constantsBuffer.write('$eol$indent');
       }
       constantsBuffer.write(field.name);
       var invocation = field.instanceCreation;

pkg/analysis_server/test/src/services/correction/assist/convert_class_to_enum_test.dart

@@ -19,6 +19,95 @@ class ConvertClassToEnumTest extends AssistProcessorTest {
   @override
   AssistKind get kind => DartAssistKind.CONVERT_CLASS_TO_ENUM;
 
+  Future<void> test_documentationComments_mix() async {
+    await resolveTestCode('''
+class E {
+  /// AAA
+  static const E a = E._('a');
+  static const E b = E._('b');
+
+  /// CCC
+  static const E c = E._('c');
+
+  final String name;
+
+  const E._(this.name);
+}
+''');
+    await assertHasAssistAt('E {', '''
+enum E {
+  /// AAA
+  a._('a'),
+  b._('b'),
+
+  /// CCC
+  c._('c');
+
+  final String name;
+
+  const E._(this.name);
+}
+''');
+  }
+
+  Future<void> test_documentationComments_multiple() async {
+    await resolveTestCode('''
+class E {
+  /// AAA
+  static const E a = E._('a');
+
+  /// BBB
+  /// BBB
+  static const E b = E._('b');
+
+  /// Name.
+  final String name;
+
+  const E._(this.name);
+}
+''');
+    await assertHasAssistAt('E {', '''
+enum E {
+  /// AAA
+  a._('a'),
+
+  /// BBB
+  /// BBB
+  b._('b');
+
+  /// Name.
+  final String name;
+
+  const E._(this.name);
+}
+''');
+  }
+
+  Future<void> test_documentationComments_single() async {
+    await resolveTestCode('''
+class E {
+  /// AAA
+  static const E a = E._('a');
+
+  /// Name.
+  final String name;
+
+  const E._(this.name);
+}
+''');
+    await assertHasAssistAt('E {', '''
+enum E {
+  /// AAA
+  a._('a');
+
+  /// Name.
+  final String name;
+
+  const E._(this.name);
+}
+''');
+  }
+
   Future<void> test_extends_object_privateClass() async {
     await resolveTestCode('''
 class _E extends Object {

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

@@ -75,6 +75,35 @@ class ConvertClassToEnumTest extends FixProcessorLintTest {
   @override
   String get lintCode => LintNames.use_enums;
 
+  Future<void> test_minimal_documentationComments() async {
+    await resolveTestCode('''
+class E {
+  /// C0.
+  static const E c0 = E._(0);
+
+  /// C1.
+  static const E c1 = E._(1);
+
+  final int value;
+
+  const E._(this.value);
+}
+''');
+    await assertHasFix('''
+enum E {
+  /// C0.
+  c0._(0),
+
+  /// C1.
+  c1._(1);
+
+  final int value;
+
+  const E._(this.value);
+}
+''');
+  }
+
   Future<void> test_minimal_intField_privateClass() async {
     await resolveTestCode('''
 class _E {