test runtime lifecycle callback (#37897)

Summary:
Pull Request resolved: #37897

Changelog: [Internal]

adding unit test for `instance:didInitializeRuntime`

Reviewed By: cipolleschi

Differential Revision: D46704036

fbshipit-source-id: 6418bae56ae465f6ed9addde75d4de5719f402bb

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

@@ -134,15 +134,25 @@ - (void)testDidReceiveErrorStack
   stackFrame0[@"file"] = @"file2.js";
   [stack addObject:stackFrame1];
 
-  [instanceDelegate instance:OCMClassMock([RCTInstance class])
-      didReceiveJSErrorStack:stack
-                     message:@"message"
-                 exceptionId:5
-                     isFatal:YES];
+  [instanceDelegate instance:[OCMArg any] didReceiveJSErrorStack:stack message:@"message" exceptionId:5 isFatal:YES];
 
   OCMVerify(
       OCMTimes(1),
       [_mockHostDelegate host:_subject didReceiveJSErrorStack:stack message:@"message" exceptionId:5 isFatal:YES]);
 }
 
+- (void)testDidInitializeRuntime
+{
+  id<RCTHostRuntimeDelegate> mockRuntimeDelegate = OCMProtocolMock(@protocol(RCTHostRuntimeDelegate));
+  _subject.runtimeDelegate = mockRuntimeDelegate;
+
+  auto hermesRuntime = facebook::hermes::makeHermesRuntime();
+  facebook::jsi::Runtime *rt = hermesRuntime.get();
+
+  id<RCTInstanceDelegate> instanceDelegate = (id<RCTInstanceDelegate>)_subject;
+  [instanceDelegate instance:[OCMArg any] didInitializeRuntime:*rt];
+
+  OCMVerify(OCMTimes(1), [mockRuntimeDelegate host:_subject didInitializeRuntime:*rt]);
+}
+
 @end