fix metric module code coverage (#3439)

Summary:
Pull Request resolved: #3439

Add missing test cases. RecMetricModule does not support async_compute().

Reviewed By: nipung90

Differential Revision: D84070148

fbshipit-source-id: f791da40f41950f66fc05f570826dfe4cf6918b0

Author: jeffkbkim

torchrec/metrics/tests/test_metric_module.py

@@ -7,6 +7,7 @@
 
 # pyre-strict
 
+import concurrent
 import copy
 import dataclasses
 import logging
@@ -42,7 +43,7 @@
     ThroughputDef,
 )
 from torchrec.metrics.model_utils import parse_task_model_outputs
-from torchrec.metrics.rec_metric import RecMetricList, RecTaskInfo
+from torchrec.metrics.rec_metric import RecMetricException, RecMetricList, RecTaskInfo
 from torchrec.metrics.test_utils import gen_test_batch
 from torchrec.metrics.throughput import ThroughputMetric
 from torchrec.test_utils import get_free_port, seed_and_log, skip_if_asan_class
@@ -647,6 +648,22 @@ def test_save_and_load_state_dict(self) -> None:
         # Make sure num_batch wasn't created on the throughput module (and no exception was thrown above)
         self.assertFalse(hasattr(no_bss_metric_module.throughput_metric, "_num_batch"))
 
+    def test_async_compute_raises_exception(self) -> None:
+        metric_module = generate_metric_module(
+            TestMetricModule,
+            metrics_config=DefaultMetricsConfig,
+            batch_size=128,
+            world_size=1,
+            my_rank=0,
+            state_metrics_mapping={},
+            device=torch.device("cpu"),
+        )
+        with self.assertRaisesRegex(
+            RecMetricException,
+            "async_compute is not supported in RecMetricModule",
+        ):
+            metric_module.async_compute(concurrent.futures.Future())
+
 
 def metric_module_gather_state(
     rank: int,
@@ -702,6 +719,8 @@ def metric_module_gather_state(
             new_tensor = new_computed_value[metric]
             torch.testing.assert_close(tensor, new_tensor, check_device=False)
 
+        metric_module.shutdown()
+
 
 @skip_if_asan_class
 class MetricModuleDistributedTest(MultiProcessTestBase):