rm_stm/tests: add test for producer expiration without data batches

In earlier versions we were not considering transactions without data
batches as candidates for expiry, thats not the case any more with
redpanda-data#18076, adding a
regression test to future proof.

src/v/cluster/tests/rm_stm_test_fixture.h

@@ -69,6 +69,8 @@ struct rm_stm_test_fixture : simple_raft_fixture {
         return _stm->wait(raft_offset, model::timeout_clock::now() + 10ms);
     }
 
+    auto get_expired_producers() const { return _stm->get_expired_producers(); }
+
     ss::sharded<cluster::tx_gateway_frontend> tx_gateway_frontend;
     ss::sharded<cluster::producer_state_manager> producer_state_manager;
     ss::shared_ptr<cluster::rm_stm> _stm;

src/v/cluster/tests/rm_stm_tests.cc

@@ -927,3 +927,28 @@ FIXTURE_TEST(test_snapshot_v3_v4_v5_equivalence, rm_stm_test_fixture) {
           highest_pid_from_snapshot, _stm->highest_producer_id());
     }
 }
+
+FIXTURE_TEST(test_tx_expiration_without_data_batches, rm_stm_test_fixture) {
+    create_stm_and_start_raft();
+    auto& stm = *_stm;
+    stm.start().get0();
+    stm.testing_only_disable_auto_abort();
+
+    wait_for_confirmed_leader();
+    wait_for_meta_initialized();
+    // Add a fence batch
+    auto pid = model::producer_identity{0, 0};
+    auto term_op = stm
+                     .begin_tx(
+                       pid,
+                       model::tx_seq{0},
+                       std::chrono::milliseconds(10),
+                       model::partition_id(0))
+                     .get0();
+    BOOST_REQUIRE(term_op.has_value());
+    BOOST_REQUIRE_EQUAL(term_op.value(), _raft->confirmed_term());
+    tests::cooperative_spin_wait_with_timeout(5s, [this, pid]() {
+        auto expired = get_expired_producers();
+        return std::find(expired.begin(), expired.end(), pid) != expired.end();
+    }).get0();
+}