lift out ShimRCTInstance to RCTTestUtils (#37859)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/37859

Changelog: [Internal]

as title

Reviewed By: cipolleschi

Differential Revision: D46547014

fbshipit-source-id: ca89d659d24fa0fcef1c39fc47fc758cee34f7d8

packages/react-native/ReactCommon/react/bridgeless/iostests/RCTHostTests.mm

@@ -7,7 +7,7 @@
 
 #import <XCTest/XCTest.h>
 
-#import <RCTTestUtils/RCTSwizzleHelpers.h>
+#import <RCTTestUtils/ShimRCTInstance.h>
 #import <ReactCommon/RCTHermesInstance.h>
 #import <ReactCommon/RCTHost.h>
 #import <ReactCommon/RCTInstance.h>
@@ -15,9 +15,6 @@
 
 #import <OCMock/OCMock.h>
 
-@interface ShimRCTInstance : NSObject
-@end
-
 @interface RCTHostTests : XCTestCase
 @end
 
@@ -50,29 +47,3 @@ static ShimRCTInstance *shimmedRCTInstance;
 }
 
 @end
-
-@implementation ShimRCTInstance
-
-- (instancetype)init
-{
-  if (self = [super init]) {
-    RCTSwizzleInstanceSelector(
-        [RCTInstance class],
-        [ShimRCTInstance class],
-        @selector(initWithDelegate:
-                  jsEngineInstance:bundleManager:turboModuleManagerDelegate:onInitialBundleLoad:moduleRegistry:));
-  }
-  return self;
-}
-
-- (instancetype)initWithDelegate:(id<RCTInstanceDelegate>)delegate
-                jsEngineInstance:(std::shared_ptr<facebook::react::JSEngineInstance>)jsEngineInstance
-                   bundleManager:(RCTBundleManager *)bundleManager
-      turboModuleManagerDelegate:(id<RCTTurboModuleManagerDelegate>)tmmDelegate
-             onInitialBundleLoad:(RCTInstanceInitialBundleLoadCompletionBlock)onInitialBundleLoad
-                  moduleRegistry:(RCTModuleRegistry *)moduleRegistry
-{
-  return self;
-}
-
-@end

packages/react-native/ReactCommon/react/test_utils/ios/Shims/ShimRCTInstance.h

@@ -0,0 +1,11 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#import <Foundation/Foundation.h>
+
+@interface ShimRCTInstance : NSObject
+@end

packages/react-native/ReactCommon/react/test_utils/ios/Shims/ShimRCTInstance.mm

@@ -0,0 +1,38 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#import "ShimRCTInstance.h"
+
+#import <ReactCommon/RCTInstance.h>
+
+#import "RCTSwizzleHelpers.h"
+
+@implementation ShimRCTInstance
+
+- (instancetype)init
+{
+  if (self = [super init]) {
+    RCTSwizzleInstanceSelector(
+        [RCTInstance class],
+        [ShimRCTInstance class],
+        @selector(initWithDelegate:
+                  jsEngineInstance:bundleManager:turboModuleManagerDelegate:onInitialBundleLoad:moduleRegistry:));
+  }
+  return self;
+}
+
+- (instancetype)initWithDelegate:(id<RCTInstanceDelegate>)delegate
+                jsEngineInstance:(std::shared_ptr<facebook::react::JSEngineInstance>)jsEngineInstance
+                   bundleManager:(RCTBundleManager *)bundleManager
+      turboModuleManagerDelegate:(id<RCTTurboModuleManagerDelegate>)tmmDelegate
+             onInitialBundleLoad:(RCTInstanceInitialBundleLoadCompletionBlock)onInitialBundleLoad
+                  moduleRegistry:(RCTModuleRegistry *)moduleRegistry
+{
+  return self;
+}
+
+@end