From 74595907a2b70a600522a8be3d4e3f48f0eb414c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Rub=C3=A9n=20Norte?= <rubennorte@meta.com>
Date: Tue, 5 Mar 2024 04:10:44 -0800
Subject: [PATCH] Add JSI test for queueMicrotask and drainMicrotasks (#43309)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/43309

Changelog: [internal]

X-link: https://github.com/facebook/hermes/pull/1336

Add JSI test verifying the behavior of `queueMicrotask` and `drainMicrotasks` in the runtimes that support them.

Reviewed By: neildhar

Differential Revision: D54484771

fbshipit-source-id: e8c0c8e05215d59a0a8c86161452642c41bcdbd7
---
 .../ReactCommon/jsi/jsi/test/testlib.cpp      | 32 +++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/packages/react-native/ReactCommon/jsi/jsi/test/testlib.cpp b/packages/react-native/ReactCommon/jsi/jsi/test/testlib.cpp
index 8291d428b35..d9090bdb2aa 100644
--- a/packages/react-native/ReactCommon/jsi/jsi/test/testlib.cpp
+++ b/packages/react-native/ReactCommon/jsi/jsi/test/testlib.cpp
@@ -1358,6 +1358,38 @@ TEST_P(JSITest, JSErrorTest) {
       JSIException);
 }
 
+TEST_P(JSITest, MicrotasksTest) {
+  try {
+    rt.global().setProperty(rt, "globalValue", String::createFromAscii(rt, ""));
+
+    auto microtask1 =
+        function("function microtask1() { globalValue += 'hello'; }");
+    auto microtask2 =
+        function("function microtask2() { globalValue += ' world' }");
+
+    rt.queueMicrotask(microtask1);
+    rt.queueMicrotask(microtask2);
+
+    EXPECT_EQ(
+        rt.global().getProperty(rt, "globalValue").asString(rt).utf8(rt), "");
+
+    rt.drainMicrotasks();
+
+    EXPECT_EQ(
+        rt.global().getProperty(rt, "globalValue").asString(rt).utf8(rt),
+        "hello world");
+
+    // Microtasks shouldn't run again
+    rt.drainMicrotasks();
+
+    EXPECT_EQ(
+        rt.global().getProperty(rt, "globalValue").asString(rt).utf8(rt),
+        "hello world");
+  } catch (const JSINativeException& ex) {
+    // queueMicrotask() is unimplemented by some runtimes, ignore such failures.
+  }
+}
+
 //----------------------------------------------------------------------
 // Test that multiple levels of delegation in DecoratedHostObjects works.