[Flutter Driver] Simplified the serialization/deserialization logic of the Descendant/… (#40715)

* Simplified the serialization/deserialization logic of the Descendant/Ancestor matchers

packages/flutter_driver/lib/src/common/find.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'dart:convert';
+
 import 'package:meta/meta.dart';
 
 import 'error.dart';
@@ -338,9 +340,9 @@ class Descendant extends SerializableFinder {
   @override
   Map<String, String> serialize() {
     return super.serialize()
-        ..addAll(of.serialize().map((String key, String value) => MapEntry<String, String>('of_$key', value)))
-        ..addAll(matching.serialize().map((String key, String value) => MapEntry<String, String>('matching_$key', value)))
         ..addAll(<String, String>{
+          'of': jsonEncode(of.serialize()),
+          'matching': jsonEncode(matching.serialize()),
           'matchRoot': matchRoot ? 'true' : 'false',
           'firstMatchOnly': firstMatchOnly ? 'true' : 'false',
         });
@@ -348,23 +350,15 @@ class Descendant extends SerializableFinder {
 
   /// Deserializes the finder from JSON generated by [serialize].
   static Descendant deserialize(Map<String, String> json) {
-    final Map<String, String> of = <String, String>{};
-    final Map<String, String> matching = <String, String>{};
-    final Map<String, String> other = <String, String>{};
-    for (String key in json.keys) {
-      if (key.startsWith('of_')) {
-        of[key.substring('of_'.length)] = json[key];
-      } else if (key.startsWith('matching_')) {
-        matching[key.substring('matching_'.length)] = json[key];
-      } else {
-        other[key] = json[key];
-      }
-    }
+    final Map<String, String> jsonOfMatcher =
+        Map<String, String>.from(jsonDecode(json['of']));
+    final Map<String, String> jsonMatchingMatcher =
+        Map<String, String>.from(jsonDecode(json['matching']));
     return Descendant(
-      of: SerializableFinder.deserialize(of),
-      matching: SerializableFinder.deserialize(matching),
-      matchRoot: other['matchRoot'] == 'true',
-      firstMatchOnly: other['firstMatchOnly'] == 'true',
+      of: SerializableFinder.deserialize(jsonOfMatcher),
+      matching: SerializableFinder.deserialize(jsonMatchingMatcher),
+      matchRoot: json['matchRoot'] == 'true',
+      firstMatchOnly: json['firstMatchOnly'] == 'true',
     );
   }
 }
@@ -401,9 +395,9 @@ class Ancestor extends SerializableFinder {
   @override
   Map<String, String> serialize() {
     return super.serialize()
-      ..addAll(of.serialize().map((String key, String value) => MapEntry<String, String>('of_$key', value)))
-      ..addAll(matching.serialize().map((String key, String value) => MapEntry<String, String>('matching_$key', value)))
       ..addAll(<String, String>{
+        'of': jsonEncode(of.serialize()),
+        'matching': jsonEncode(matching.serialize()),
         'matchRoot': matchRoot ? 'true' : 'false',
         'firstMatchOnly': firstMatchOnly ? 'true' : 'false',
       });
@@ -411,23 +405,15 @@ class Ancestor extends SerializableFinder {
 
   /// Deserializes the finder from JSON generated by [serialize].
   static Ancestor deserialize(Map<String, String> json) {
-    final Map<String, String> of = <String, String>{};
-    final Map<String, String> matching = <String, String>{};
-    final Map<String, String> other = <String, String>{};
-    for (String key in json.keys) {
-      if (key.startsWith('of_')) {
-        of[key.substring('of_'.length)] = json[key];
-      } else if (key.startsWith('matching_')) {
-        matching[key.substring('matching_'.length)] = json[key];
-      } else {
-        other[key] = json[key];
-      }
-    }
+    final Map<String, String> jsonOfMatcher =
+        Map<String, String>.from(jsonDecode(json['of']));
+    final Map<String, String> jsonMatchingMatcher =
+        Map<String, String>.from(jsonDecode(json['matching']));
     return Ancestor(
-      of: SerializableFinder.deserialize(of),
-      matching: SerializableFinder.deserialize(matching),
-      matchRoot: other['matchRoot'] == 'true',
-      firstMatchOnly: other['firstMatchOnly'] == 'true',
+      of: SerializableFinder.deserialize(jsonOfMatcher),
+      matching: SerializableFinder.deserialize(jsonMatchingMatcher),
+      matchRoot: json['matchRoot'] == 'true',
+      firstMatchOnly: json['firstMatchOnly'] == 'true',
     );
   }
 }

packages/flutter_driver/test/src/find_test.dart

@@ -19,11 +19,8 @@ void main() {
     );
     expect(a.serialize(), <String, String>{
       'finderType': 'Ancestor',
-      'of_finderType': 'ByType',
-      'of_type': 'Text',
-      'matching_finderType': 'ByValueKey',
-      'matching_keyValueString': 'hello',
-      'matching_keyValueType': 'String',
+      'of': '{"finderType":"ByType","type":"Text"}',
+      'matching': '{"finderType":"ByValueKey","keyValueString":"hello","keyValueType":"String"}',
       'matchRoot': 'true',
       'firstMatchOnly': 'true',
     });
@@ -32,11 +29,8 @@ void main() {
   test('Ancestor finder deserialize', () {
     final Map<String, String> serialized = <String, String>{
       'finderType': 'Ancestor',
-      'of_finderType': 'ByType',
-      'of_type': 'Text',
-      'matching_finderType': 'ByValueKey',
-      'matching_keyValueString': 'hello',
-      'matching_keyValueType': 'String',
+      'of': '{"finderType":"ByType","type":"Text"}',
+      'matching': '{"finderType":"ByValueKey","keyValueString":"hello","keyValueType":"String"}',
       'matchRoot': 'true',
       'firstMatchOnly': 'true',
     };
@@ -60,11 +54,8 @@ void main() {
     );
     expect(a.serialize(), <String, String>{
       'finderType': 'Descendant',
-      'of_finderType': 'ByType',
-      'of_type': 'Text',
-      'matching_finderType': 'ByValueKey',
-      'matching_keyValueString': 'hello',
-      'matching_keyValueType': 'String',
+      'of': '{"finderType":"ByType","type":"Text"}',
+      'matching': '{"finderType":"ByValueKey","keyValueString":"hello","keyValueType":"String"}',
       'matchRoot': 'true',
       'firstMatchOnly': 'true',
     });
@@ -73,11 +64,8 @@ void main() {
   test('Descendant finder deserialize', () {
     final Map<String, String> serialized = <String, String>{
       'finderType': 'Descendant',
-      'of_finderType': 'ByType',
-      'of_type': 'Text',
-      'matching_finderType': 'ByValueKey',
-      'matching_keyValueString': 'hello',
-      'matching_keyValueType': 'String',
+      'of': '{"finderType":"ByType","type":"Text"}',
+      'matching': '{"finderType":"ByValueKey","keyValueString":"hello","keyValueType":"String"}',
       'matchRoot': 'true',
       'firstMatchOnly': 'true',
     };