Better error message if table has no columns, closes #424

Author: simonw

sqlite_utils/db.py

@@ -768,6 +768,7 @@ def create_table_sql(
         # Soundness check not_null, and defaults if provided
         not_null = not_null or set()
         defaults = defaults or {}
+        assert columns, "Tables must have at least one column"
         assert all(
             n in columns for n in not_null
         ), "not_null set {} includes items not in columns {}".format(

tests/test_create.py

@@ -1149,3 +1149,9 @@ def test_create_if_not_exists(fresh_db):
         fresh_db["t"].create({"id": int})
     # This should not
     fresh_db["t"].create({"id": int}, if_not_exists=True)
+
+
+def test_create_if_no_columns(fresh_db):
+    with pytest.raises(AssertionError) as error:
+        fresh_db["t"].create({})
+    assert error.value.args[0] == "Tables must have at least one column"