Fix and polish seed warnings in tests (#5822)

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>

Author: nickmuoh

sqlmesh/core/engine_adapter/snowflake.py

@@ -407,7 +407,7 @@ def query_factory() -> Query:
             elif isinstance(df, pd.DataFrame):
                 from snowflake.connector.pandas_tools import write_pandas
 
-                ordered_df = df[list(source_columns_to_types)]
+                ordered_df = df[list(source_columns_to_types)].reset_index(drop=True)
 
                 # Workaround for https://github.com/snowflakedb/snowflake-connector-python/issues/1034
                 # The above issue has already been fixed upstream, but we keep the following

sqlmesh/core/model/seed.py

@@ -113,7 +113,7 @@ def read(self, batch_size: t.Optional[int] = None) -> t.Generator[pd.DataFrame,
         batch_size = batch_size or df.size
         batch_start = 0
         while batch_start < df.shape[0]:
-            yield df.iloc[batch_start : batch_start + batch_size, :]
+            yield df.iloc[batch_start : batch_start + batch_size, :].copy()
             batch_start += batch_size
 
     def _get_df(self) -> pd.DataFrame:

tests/core/engine_adapter/test_snowflake.py

@@ -469,6 +469,26 @@ def test_df_to_source_queries_use_schema(
     assert 'USE SCHEMA "other_catalog"."other_db"' in to_sql_calls(adapter)
 
 
+def test_df_to_source_queries_reset_non_default_index(
+    make_mocked_engine_adapter: t.Callable, mocker: MockerFixture
+):
+    mocker.patch(
+        "sqlmesh.core.engine_adapter.snowflake.SnowflakeEngineAdapter.table_exists",
+        return_value=False,
+    )
+    write_pandas = mocker.patch("snowflake.connector.pandas_tools.write_pandas", return_value=None)
+    adapter = make_mocked_engine_adapter(SnowflakeEngineAdapter)
+
+    df = pd.DataFrame({"a": [2, 3], "b": [5, 6]}, index=[1, 2])
+    adapter.replace_query(
+        "other_db.test_table", df, {"a": exp.DataType.build("INT"), "b": exp.DataType.build("INT")}
+    )
+
+    uploaded_df = write_pandas.call_args.args[1]
+    assert uploaded_df.index.equals(pd.RangeIndex(start=0, stop=2, step=1))
+    assert uploaded_df.to_dict("list") == {"a": [2, 3], "b": [5, 6]}
+
+
 def test_create_managed_table(make_mocked_engine_adapter: t.Callable, mocker: MockerFixture):
     adapter = make_mocked_engine_adapter(SnowflakeEngineAdapter)
 

tests/core/test_seed.py

@@ -58,6 +58,21 @@ def test_read_custom_settings():
     pd.testing.assert_frame_equal(next(dfs), expected_df)
 
 
+def test_read_returns_independent_batches():
+    content = """key,value
+1,one
+2,two
+"""
+    seed = Seed(content=content)
+    seed_reader = seed.reader()
+
+    batches = list(seed_reader.read(batch_size=1))
+    batches[0].at[0, "value"] = "changed"
+
+    assert [df["value"].tolist() for df in batches] == [["changed"], ["two"]]
+    assert next(seed_reader.read())["value"].tolist() == ["one", "two"]
+
+
 def test_column_hashes():
     content = """key,value,ds
 1,one,2022-01-01