Add test coverage for comment copying

Author: greglittlefield-wf

test_fixtures/gold_output_files/backwards_compatible/basic.over_react.g.dart.goldFile

@@ -20,13 +20,17 @@ abstract class _$BasicPropsAccessorsMixin implements _$BasicProps {
   @override
   Map get props;
 
+  /// Test that doc comment is copied over.
+  ///
   /// <!-- Generated from [_$BasicProps.basicProp] -->
   @override
   @deprecated
   @requiredProp
   String get basicProp =>
       props[_$key__basicProp___$BasicProps] ??
       null; // Add ` ?? null` to workaround DDC bug: <https://github.com/dart-lang/sdk/issues/36052>;
+  /// Test that doc comment is copied over.
+  ///
   /// <!-- Generated from [_$BasicProps.basicProp] -->
   @override
   @deprecated

test_fixtures/gold_output_files/backwards_compatible/basic_library.over_react.g.dart.goldFile

@@ -22,11 +22,15 @@ abstract class _$BasicPartOfLibPropsAccessorsMixin
   @override
   Map get props;
 
+  /// Test that doc comment is copied over.
+  ///
   /// <!-- Generated from [_$BasicPartOfLibProps.basicProp] -->
   @override
   String get basicProp =>
       props[_$key__basicProp___$BasicPartOfLibProps] ??
       null; // Add ` ?? null` to workaround DDC bug: <https://github.com/dart-lang/sdk/issues/36052>;
+  /// Test that doc comment is copied over.
+  ///
   /// <!-- Generated from [_$BasicPartOfLibProps.basicProp] -->
   @override
   set basicProp(String value) =>

test_fixtures/gold_output_files/basic.over_react.g.dart.goldFile

@@ -20,13 +20,17 @@ abstract class _$BasicPropsAccessorsMixin implements _$BasicProps {
   @override
   Map get props;
 
+  /// Test that doc comment is copied over.
+  ///
   /// <!-- Generated from [_$BasicProps.basicProp] -->
   @override
   @deprecated
   @requiredProp
   String get basicProp =>
       props[_$key__basicProp___$BasicProps] ??
       null; // Add ` ?? null` to workaround DDC bug: <https://github.com/dart-lang/sdk/issues/36052>;
+  /// Test that doc comment is copied over.
+  ///
   /// <!-- Generated from [_$BasicProps.basicProp] -->
   @override
   @deprecated

test_fixtures/gold_output_files/basic_library.over_react.g.dart.goldFile

@@ -22,11 +22,15 @@ abstract class _$BasicPartOfLibPropsAccessorsMixin
   @override
   Map get props;
 
+  /// Test that doc comment is copied over.
+  ///
   /// <!-- Generated from [_$BasicPartOfLibProps.basicProp] -->
   @override
   String get basicProp =>
       props[_$key__basicProp___$BasicPartOfLibProps] ??
       null; // Add ` ?? null` to workaround DDC bug: <https://github.com/dart-lang/sdk/issues/36052>;
+  /// Test that doc comment is copied over.
+  ///
   /// <!-- Generated from [_$BasicPartOfLibProps.basicProp] -->
   @override
   set basicProp(String value) =>

test_fixtures/source_files/backwards_compatible/basic.dart

@@ -12,6 +12,7 @@ class BasicProps extends _$BasicProps with _$BasicPropsAccessorsMixin {
 @Props()
 //// ignore: mixin_of_non_class,undefined_class
 class _$BasicProps extends UiProps {
+  /// Test that doc comment is copied over.
   @deprecated
   @requiredProp
   String basicProp;

test_fixtures/source_files/backwards_compatible/part_of_basic_library.dart

@@ -12,6 +12,7 @@ class BasicPartOfLibProps extends _$BasicPartOfLibProps with _$BasicPartOfLibPro
 class _$BasicPartOfLibProps extends UiProps
     with  ExamplePropsMixinClass, $ExamplePropsMixinClass {
 
+  /// Test that doc comment is copied over.
   String basicProp;
   String basic1;
   String basic2;

test_fixtures/source_files/basic.dart

@@ -8,6 +8,7 @@ UiFactory<BasicProps> Basic = _$Basic;
 @Props()
 //// ignore: mixin_of_non_class,undefined_class
 class _$BasicProps extends UiProps {
+  /// Test that doc comment is copied over.
   @deprecated
   @requiredProp
   String basicProp;

test_fixtures/source_files/part_of_basic_library.dart

@@ -7,6 +7,7 @@ UiFactory<BasicPartOfLibProps> BasicPartOfLib = _$BasicPartOfLib;
 class _$BasicPartOfLibProps extends UiProps
     with ExamplePropsMixinClass {
 
+  /// Test that doc comment is copied over.
   String basicProp;
   String basic1;
   String basic2;