Decouple isTesting Platform flag from disabling/enabling animations when testing (#38490)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/38490

## Changelog
[Internal] -

The internal `Platform.isTesting` is tightly coupled to animations being disabled, which in turn can lead to subtle problems in some of the corner cases:
* Since `isTesting` is force override to `false` on JS side in non-dev builds, it means that e2e tests, that would like to use release builds, are out of luck when animation disabling is desired
* Conversely, some of the e2e tests may actually rely on animations being enabled in order to work, which means they are also out of luck if trying to test a dev build
* Finally, we have cases of hybrid builds, which are build in release on native side, but also have `__DEV__=true` on the native side

To both cover the above scenarios, but also to be backwards compatible to all the existing once, this change introduces another flag, `Platform.isDisableAnimations`.

The way it works is:
* If it's not specified, the e2e tests behaviour will be exactly the same as before, since by default `isDisableAnimations` will be true when `isTesting` is true
* If it's specified and is equal to `false`, it means that animations will be still enabled, even if `isTesting` is true (for those e2e tests that rely on animations being enabled)
* If it's specified and is equal to 'true', it means that animations will be force disabled, no matter whether we test a release or a dev build

Note that this only specifies the JS side of things, defaulting `Platform.isDisableAnimations` to "not specified" (i.e. all the tests will behave as before).

Pulling it through for different platforms is done as a separate follow-up.

Differential Revision: D47516800

fbshipit-source-id: efcb78f68f9102fec025ecce9a475c9c0bc1ecca

packages/react-native/Libraries/Animated/Animated.js

@@ -21,7 +21,7 @@ import Platform from '../Utilities/Platform';
 import AnimatedImplementation from './AnimatedImplementation';
 import AnimatedMock from './AnimatedMock';
 
-const Animated = ((Platform.isTesting
+const Animated = ((Platform.isDisableAnimations
   ? AnimatedMock
   : AnimatedImplementation): typeof AnimatedImplementation);
 

packages/react-native/Libraries/LayoutAnimation/LayoutAnimation.js

@@ -49,7 +49,7 @@ function configureNext(
   onAnimationDidEnd?: OnAnimationDidEndCallback,
   onAnimationDidFail?: OnAnimationDidFailCallback,
 ) {
-  if (Platform.isTesting) {
+  if (Platform.isDisableAnimations) {
     return;
   }
 

packages/react-native/Libraries/Utilities/NativePlatformConstantsAndroid.js

@@ -15,6 +15,7 @@ import * as TurboModuleRegistry from '../TurboModule/TurboModuleRegistry';
 export interface Spec extends TurboModule {
   +getConstants: () => {|
     isTesting: boolean,
+    isDisableAnimations?: boolean,
     reactNativeVersion: {|
       major: number,
       minor: number,

packages/react-native/Libraries/Utilities/NativePlatformConstantsIOS.js

@@ -15,6 +15,7 @@ import * as TurboModuleRegistry from '../TurboModule/TurboModuleRegistry';
 export interface Spec extends TurboModule {
   +getConstants: () => {|
     isTesting: boolean,
+    isDisableAnimations?: boolean,
     reactNativeVersion: {|
       major: number,
       minor: number,

packages/react-native/Libraries/Utilities/Platform.android.js

@@ -28,6 +28,7 @@ const Platform = {
   // $FlowFixMe[unsafe-getters-setters]
   get constants(): {|
     isTesting: boolean,
+    isDisableAnimations?: boolean,
     reactNativeVersion: {|
       major: number,
       minor: number,
@@ -61,6 +62,11 @@ const Platform = {
     return false;
   },
   // $FlowFixMe[unsafe-getters-setters]
+  get isDisableAnimations(): boolean {
+    // $FlowFixMe[object-this-reference]
+    return this.constants.isDisableAnimations ?? this.isTesting;
+  },
+  // $FlowFixMe[unsafe-getters-setters]
   get isTV(): boolean {
     // $FlowFixMe[object-this-reference]
     return this.constants.uiMode === 'tv';

packages/react-native/Libraries/Utilities/Platform.d.ts

@@ -19,6 +19,7 @@ export type PlatformOSType =
   | 'native';
 type PlatformConstants = {
   isTesting: boolean;
+  isDisableAnimations?: boolean | undefined;
   reactNativeVersion: {
     major: number;
     minor: number;

packages/react-native/Libraries/Utilities/Platform.ios.js

@@ -30,6 +30,7 @@ const Platform = {
     forceTouchAvailable: boolean,
     interfaceIdiom: string,
     isTesting: boolean,
+    isDisableAnimations?: boolean,
     osVersion: string,
     reactNativeVersion: {|
       major: number,
@@ -65,6 +66,11 @@ const Platform = {
     }
     return false;
   },
+  // $FlowFixMe[unsafe-getters-setters]
+  get isDisableAnimations(): boolean {
+    // $FlowFixMe[object-this-reference]
+    return this.constants.isDisableAnimations ?? this.isTesting;
+  },
   select: <T>(spec: PlatformSelectSpec<T>): T =>
     // $FlowFixMe[incompatible-return]
     'ios' in spec ? spec.ios : 'native' in spec ? spec.native : spec.default,