1 files changed, 74 insertions, 0 deletions
diff --git a/test/js/web/timers/microtask.test.js b/test/js/web/timers/microtask.test.js
new file mode 100644
index 000000000..f41159cfa
--- /dev/null
+++ b/test/js/web/timers/microtask.test.js
@@ -0,0 +1,74 @@
+import { it } from "bun:test";
+
+it("queueMicrotask", async () => {
+  // You can verify this test is correct by copy pasting this into a browser's console and checking it doesn't throw an error.
+  var run = 0;
+
+  await new Promise((resolve, reject) => {
+    queueMicrotask(() => {
+      if (run++ != 0) {
+        reject(new Error("Microtask execution order is wrong: " + run));
+      }
+      queueMicrotask(() => {
+        if (run++ != 3) {
+          reject(new Error("Microtask execution order is wrong: " + run));
+        }
+      });
+    });
+    queueMicrotask(() => {
+      if (run++ != 1) {
+        reject(new Error("Microtask execution order is wrong: " + run));
+      }
+      queueMicrotask(() => {
+        if (run++ != 4) {
+          reject(new Error("Microtask execution order is wrong: " + run));
+        }
+
+        queueMicrotask(() => {
+          if (run++ != 6) {
+            reject(new Error("Microtask execution order is wrong: " + run));
+          }
+        });
+      });
+    });
+    queueMicrotask(() => {
+      if (run++ != 2) {
+        reject(new Error("Microtask execution order is wrong: " + run));
+      }
+      queueMicrotask(() => {
+        if (run++ != 5) {
+          reject(new Error("Microtask execution order is wrong: " + run));
+        }
+
+        queueMicrotask(() => {
+          if (run++ != 7) {
+            reject(new Error("Microtask execution order is wrong: " + run));
+          }
+          resolve(true);
+        });
+      });
+    });
+  });
+
+  {
+    var passed = false;
+    try {
+      queueMicrotask(1234);
+    } catch (exception) {
+      passed = exception instanceof TypeError;
+    }
+
+    if (!passed) throw new Error("queueMicrotask should throw a TypeError if the argument is not a function");
+  }
+
+  {
+    var passed = false;
+    try {
+      queueMicrotask();
+    } catch (exception) {
+      passed = exception instanceof TypeError;
+    }
+
+    if (!passed) throw new Error("queueMicrotask should throw a TypeError if the argument is empty");
+  }
+});