diff --git a/src/policies/hellthread-policy.test.ts b/src/policies/hellthread-policy.test.ts
new file mode 100644
index 0000000..b350e78
--- /dev/null
+++ b/src/policies/hellthread-policy.test.ts
@@ -0,0 +1,14 @@
+import { assert } from '../deps.ts';
+import { buildEvent, buildInputMessage } from '../test.ts';
+
+import hellthreadPolicy from './hellthread-policy.ts';
+
+Deno.test('blocks events with too many mentioned users', async () => {
+  const tags = [['p'], ['p'], ['p']];
+
+  const msg0 = buildInputMessage();
+  const msg1 = buildInputMessage({ event: buildEvent({ tags }) });
+
+  assert((await hellthreadPolicy(msg0, { limit: 1 })).action === 'accept');
+  assert((await hellthreadPolicy(msg1, { limit: 1 })).action === 'reject');
+});