[plugin_platform_interface] Don't use const Object as a token (flutter#2417)

Author: amirh

packages/plugin_platform_interface/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 1.0.1
+
+* Fixed a bug that made all platform interfaces appear as mocks in release builds (https://github.com/flutter/flutter/issues/46941).
+
 ## 1.0.0 - Initial release.
 
 * Provides `PlatformInterface` with common mechanism for enforcing that a platform interface

packages/plugin_platform_interface/README.md

@@ -18,7 +18,7 @@ abstract class UrlLauncherPlatform extends PlatformInterface {
 
   static UrlLauncherPlatform _instance = MethodChannelUrlLauncher();
 
-  static const Object _token = Object();
+  static final Object _token = Object();
 
   static UrlLauncherPlatform get instance => _instance;
 

packages/plugin_platform_interface/lib/plugin_platform_interface.dart

@@ -57,7 +57,7 @@ abstract class PlatformInterface {
   /// This is implemented as a static method so that it cannot be overridden
   /// with `noSuchMethod`.
   static void verifyToken(PlatformInterface instance, Object token) {
-    if (identical(instance._instanceToken, MockPlatformInterfaceMixin._token)) {
+    if (instance is MockPlatformInterfaceMixin) {
       bool assertionsEnabled = false;
       assert(() {
         assertionsEnabled = true;
@@ -67,6 +67,7 @@ abstract class PlatformInterface {
         throw AssertionError(
             '`MockPlatformInterfaceMixin` is not intended for use in release builds.');
       }
+      return;
     }
     if (!identical(token, instance._instanceToken)) {
       throw AssertionError(
@@ -90,9 +91,4 @@ abstract class PlatformInterface {
 ///    implements UrlLauncherPlatform {}
 /// ```
 @visibleForTesting
-abstract class MockPlatformInterfaceMixin implements PlatformInterface {
-  static const Object _token = Object();
-
-  @override
-  Object get _instanceToken => _token;
-}
+abstract class MockPlatformInterfaceMixin implements PlatformInterface {}

packages/plugin_platform_interface/pubspec.yaml

@@ -12,7 +12,7 @@ description: Reusable base class for Flutter plugin platform interfaces.
 # be done when absolutely necessary and after the ecosystem has already migrated to 1.X.Y version
 # that is forward compatible with 2.0.0 (ideally the ecosystem have migrated to depend on:
 # `plugin_platform_interface: >=1.X.Y <3.0.0`).
-version: 1.0.0
+version: 1.0.1
 
 homepage: https://github.com/flutter/plugins/plugin_platform_interface
 

packages/plugin_platform_interface/test/plugin_platform_interface_test.dart

@@ -10,7 +10,7 @@ import 'package:plugin_platform_interface/plugin_platform_interface.dart';
 class SamplePluginPlatform extends PlatformInterface {
   SamplePluginPlatform() : super(token: _token);
 
-  static const Object _token = Object();
+  static final Object _token = Object();
 
   static set instance(SamplePluginPlatform instance) {
     PlatformInterface.verifyToken(instance, _token);