Add tests for interaction between import() and microtask queue

html/semantics/scripting-1/the-script-element/module/dynamic-import/microtasks/basic.any.js

@@ -0,0 +1,32 @@
+// META: global=window,dedicatedworker,sharedworker
+// META: script=ticker.js
+
+promise_test(async t => {
+  const getCount = ticker(1000);
+
+  const importP = import("<invalid>");
+  await promise_rejects_js(t, TypeError, importP, 'import() should reject');
+
+  assert_less_than(getCount(), 1000);
+}, "import() should not drain the microtask queue if it fails during specifier resolution");
+
+promise_test(async t => {
+  // Use Date.now() to ensure that the module is not in the module map
+  const specifier = "./empty-module.js?" + Date.now();
+
+  await import(specifier);
+
+  const getCount = ticker(1000);
+  await import(specifier);
+  assert_less_than(getCount(), 1000);
+}, "import() should not drain the microtask queue when loading an already loaded module");
+
+promise_test(async t => {
+  // Use Date.now() to ensure that the module is not in the module map
+  const specifier = "./empty-module.js?" + Date.now();
+
+  const getCount = ticker(1e7);
+  await import(specifier);
+  assert_equals(getCount(), 1e7);
+}, "import() should drain the microtask queue when fetching a new module");
+

html/semantics/scripting-1/the-script-element/module/dynamic-import/microtasks/css-import-in-worker.any.js

@@ -0,0 +1,14 @@
+// META: global=dedicatedworker,sharedworker
+// META: script=ticker.js
+
+promise_test(async t => {
+  // Use Date.now() to ensure that the module is not in the module map
+  const specifier = "./empty-module.css?" + Date.now();
+
+  const getCount = ticker(1000);
+
+  const importP = import(specifier, { assert: { type: "css" } });
+  await promise_rejects_js(t, TypeError, importP, 'import() should reject');
+
+  assert_less_than(getCount(), 1000);
+}, "import() should not drain the microtask queue if it fails because of the 'type: css' assertion in a worker");

html/semantics/scripting-1/the-script-element/module/dynamic-import/microtasks/empty-module.css

@@ -0,0 +1,4 @@
+/*
+This file is empty, because all it matters is if the
+dynamic import that loads it fails or succedes.
+*/

html/semantics/scripting-1/the-script-element/module/dynamic-import/microtasks/empty-module.js

@@ -0,0 +1,4 @@
+/*
+This file is empty, because all it matters is if the
+dynamic import that loads it fails or succedes.
+*/

html/semantics/scripting-1/the-script-element/module/dynamic-import/microtasks/serviceworker.any.js

@@ -0,0 +1,14 @@
+// META: global=serviceworker
+// META: script=ticker.js
+
+promise_test(async t => {
+  // Use Date.now() to ensure that the module is not in the module map
+  const specifier = "./empty-module.js?" + Date.now();
+
+  const getCount = ticker(1000);
+
+  const importP = import(specifier);
+  await promise_rejects_js(t, TypeError, importP, 'import() should reject');
+
+  assert_less_than(getCount(), 1000);
+}, "import() should not drain the microtask queue if it fails because it's used in a ServiceWorker");

html/semantics/scripting-1/the-script-element/module/dynamic-import/microtasks/ticker.js

@@ -0,0 +1,13 @@
+globalThis.ticker = function ticker(max) {
+  let i = 0;
+  let stop = false;
+  Promise.resolve().then(function loop() {
+    if (stop || i >= max) return;
+    i++;
+    Promise.resolve().then(loop);
+  });
+  return () => {
+    stop = true;
+    return i;
+  };
+};

html/semantics/scripting-1/the-script-element/module/dynamic-import/microtasks/with-import-assertions.any.js

@@ -0,0 +1,15 @@
+// META: global=window,dedicatedworker,sharedworker
+// META: script=ticker.js
+
+promise_test(async t => {
+  // Use Date.now() to ensure that the module is not in the module map
+  const specifier = "./empty-module.js?" + Date.now();
+
+  const getCount = ticker(1000);
+
+  const importP = import(specifier, { assert: { type: "<invalid>" } });
+  await promise_rejects_js(t, TypeError, importP, 'import() should reject');
+
+  assert_less_than(getCount(), 1000);
+}, "import() should not drain the microtask queue if it fails while validating the 'type' assertion");
+

html/semantics/scripting-1/the-script-element/module/dynamic-import/microtasks/worklet-ref.https.html

@@ -0,0 +1,10 @@
+<!DOCTYPE html>
+<canvas id ="output" width="100" height="100" style="background: blue;"></canvas>
+<script>
+"use strict";
+const canvas = document.getElementById('output');
+const ctx = canvas.getContext('2d');
+
+ctx.fillStyle = 'green';
+ctx.fillRect(0, 0, 100, 100);
+</script>

html/semantics/scripting-1/the-script-element/module/dynamic-import/microtasks/worklet.https.html

@@ -0,0 +1,43 @@
+<!DOCTYPE html>
+<html class="reftest-wait">
+<link rel="help" href="https://html.spec.whatwg.org/#hostimportmoduledynamically(referencingscriptormodule,-specifier,-promisecapability)">
+<link rel="match" href="worklet-ref.html">
+<style>
+#output {
+    width: 100px;
+    height: 100px;
+    background-image: paint(rects);
+    background-color: blue;
+}
+</style>
+<script src="/common/reftest-wait.js"></script>
+<script src="/common/worklet-reftest.js"></script>
+<body>
+<div id="output"></div>
+
+<script id="code" type="text/worklet">
+registerPaint('rects', class {
+  async paint(ctx, geom) {
+    ctx.fillStyle = 'red';
+
+    const getCount = ticker(1000);
+
+    try {
+        // Use Date.now() to ensure that the module is not in the module map
+        await import("./empty-module.js?" + Date.now());
+    } catch (e) {
+      if (getCount() < 1000) {
+        ctx.fillStyle = 'green';
+      }
+    }
+    ctx.fillRect(0, 0, geom.width, geom.height);
+  }
+});
+</script>
+
+<script>
+"use strict";
+CSS.paintWorklet.addModule("./ticker.js").then(() =>
+  importWorkletAndTerminateTestAfterAsyncPaint(CSS.paintWorklet, document.getElementById('code').textContent)
+);
+</script>