Add test for parsing a metric with a custom grain offset_window

metricflow-semantics/metricflow_semantics/test_helpers/semantic_manifest_yamls/simple_manifest/metrics.yaml

@@ -719,6 +719,16 @@ metric:
       - name: bookings_offset_once
         offset_window: 2 days
 ---
+metric:
+  name: "bookings_offset_martian_day"
+  description: bookings metric offset by a martian day.
+  type: derived
+  type_params:
+    expr: 2 * bookings
+    metrics:
+      - name: bookings
+        offset_window: 1 martian_day
+---
 metric:
   name: bookings_at_start_of_month
   description: |

metricflow-semantics/tests_metricflow_semantics/model/semantics/test_metric_lookup.py

@@ -2,6 +2,7 @@
 
 import logging
 
+from dbt_semantic_interfaces.implementations.metric import PydanticMetricTimeWindow
 from dbt_semantic_interfaces.references import MetricReference
 from dbt_semantic_interfaces.type_enums import TimeGranularity
 from metricflow_semantics.model.semantic_manifest_lookup import SemanticManifestLookup
@@ -21,3 +22,18 @@ def test_min_queryable_time_granularity_for_different_agg_time_grains(  # noqa:
     # Since `monthly_bookings_to_daily_bookings` is based on metrics with DAY and MONTH aggregation time grains,
     # the minimum queryable grain should be MONTH.
     assert min_queryable_grain == TimeGranularity.MONTH
+
+
+def test_custom_offset_window_for_metric(
+    simple_semantic_manifest_lookup: SemanticManifestLookup,
+) -> None:
+    """Test offset window with custom grain supplied.
+
+    TODO: As of now, the functionality of an offset window with a custom grain is not supported in MF.
+          This test is added to show that at least the parsing is successful using a custom grain offset window.
+          Once support for that is added in MF + relevant tests, this test can be removed.
+    """
+    metric = simple_semantic_manifest_lookup.metric_lookup.get_metric(MetricReference("bookings_offset_martian_day"))
+
+    assert len(metric.input_metrics) == 1
+    assert metric.input_metrics[0].offset_window == PydanticMetricTimeWindow(count=1, granularity="martian_day")