add test asserting all derived tables have rows

mimic-iv/tests/test_all_tables.py

@@ -0,0 +1,15 @@
+import pandas as pd
+from pandas.io import gbq
+
+def test_tables_have_data(dataset, project_id, concepts):
+    """Verifies each table has data."""
+
+    for folder, concept_list in concepts.items():
+        for concept_name in concept_list:
+            query = f"""
+            SELECT *
+            FROM {dataset}.{concept_name}
+            LIMIT 5
+            """
+            df = gbq.read_gbq(query, project_id=project_id, dialect="standard")
+            assert df.shape[0] > 0, f'did not find table for {folder}.{concept_name}'