3 files changed, 42 insertions, 0 deletions
diff --git a/cli/tests/integration/worker_tests.rs b/cli/tests/integration/worker_tests.rs
index 916e8c887..aa6d64d2b 100644
--- a/cli/tests/integration/worker_tests.rs
+++ b/cli/tests/integration/worker_tests.rs
@@ -108,3 +108,10 @@ itest!(worker_error_event {
   output: "workers/error_event.ts.out",
   exit_code: 1,
 });
+
+// Regression test for https://github.com/denoland/deno/issues/19903
+itest!(worker_doest_stall_event_loop {
+  args: "run --quiet -A workers/worker_doest_stall_event_loop.ts",
+  output: "workers/worker_doest_stall_event_loop.ts.out",
+  exit_code: 0,
+});
diff --git a/cli/tests/testdata/workers/worker_doest_stall_event_loop.ts b/cli/tests/testdata/workers/worker_doest_stall_event_loop.ts
new file mode 100644
index 000000000..bfddee2ec
--- /dev/null
+++ b/cli/tests/testdata/workers/worker_doest_stall_event_loop.ts
@@ -0,0 +1,29 @@
+const moduleCode = `
+console.log('module start');
+const hash = await crypto.subtle.digest('SHA-1', new TextEncoder().encode('data'));
+const __default = {};
+export { __default as default };
+console.log('module finish');
+`;
+
+const workerCode = `
+    console.log('worker!');
+
+    globalThis.onmessage = (msg) => {
+        const { moduleCode } = msg.data;
+        (async () => {
+            console.log('before import');
+            await import(URL.createObjectURL(new Blob([ moduleCode ])));
+            console.log('after import');
+            self.postMessage('thanks');
+        })();
+    }
+`;
+const worker = new Worker(URL.createObjectURL(new Blob([workerCode])), {
+  type: "module",
+});
+worker.onmessage = () => {
+  console.log("worker.terminate");
+  worker.terminate();
+};
+worker.postMessage({ moduleCode });
diff --git a/cli/tests/testdata/workers/worker_doest_stall_event_loop.ts.out b/cli/tests/testdata/workers/worker_doest_stall_event_loop.ts.out
new file mode 100644
index 000000000..5ed65b02f
--- /dev/null
+++ b/cli/tests/testdata/workers/worker_doest_stall_event_loop.ts.out
@@ -0,0 +1,6 @@
+worker!
+before import
+module start
+module finish
+after import
+worker.terminate