diff --git a/tests/unit/test_submit_tool.py b/tests/unit/test_submit_tool.py
index c3ecd77..13f8503 100644
--- a/tests/unit/test_submit_tool.py
+++ b/tests/unit/test_submit_tool.py
@@ -162,3 +162,29 @@ def test_get_pending_job_returns_dump(monkeypatch):
 def test_get_pending_job_unknown_raises():
     with pytest.raises(KeyError):
         submit.get_pending_job("missing")
+
+
+# --- cancel_pending_job ---
+
+def test_cancel_pending_job_marks_cancelled(monkeypatch):
+    monkeypatch.setattr(submit, "run_spark_submit", lambda cmd: None)
+    submit.prepare_submit_job(connection="prod", script_path="/tmp/j.py")
+    pid = _last_pending_id()
+    out = submit.cancel_pending_job(pid)
+    assert out == {"pending_id": pid, "status": "CANCELLED"}
+    assert submit.pending_store.get(pid).status == "CANCELLED"
+
+
+def test_cancel_pending_job_unknown_raises():
+    with pytest.raises(KeyError):
+        submit.cancel_pending_job("missing")
+
+
+def test_cancel_pending_job_refuses_submitted(monkeypatch):
+    submit.prepare_submit_job(connection="prod", script_path="/tmp/j.py")
+    pid = _last_pending_id()
+    p = submit.pending_store.get(pid)
+    p.status = "SUBMITTED"
+    submit.pending_store.save(p)
+    with pytest.raises(ValueError, match="SUBMITTED"):
+        submit.cancel_pending_job(pid)