feat: support write_pandas with partial columns

fakesnow/fakes.py

@@ -394,10 +394,11 @@ def execute_string(
         ]
         return cursors if return_cursors else []
 
-    def insert_df(
+    def _insert_df(
         self, df: pd.DataFrame, table_name: str, database: str | None = None, schema: str | None = None
     ) -> int:
-        self._duck_conn.execute(f"INSERT INTO {table_name} SELECT * FROM df")
+        cols = ",".join(df.columns.to_list())
+        self._duck_conn.execute(f"INSERT INTO {table_name}({cols}) SELECT * FROM df")
         return self._duck_conn.fetchall()[0][0]
 
 
@@ -463,7 +464,7 @@ def write_pandas(
     table_type: Literal["", "temp", "temporary", "transient"] = "",
     **kwargs: Any,
 ) -> WritePandasResult:
-    count = conn.insert_df(df, table_name, database, schema)
+    count = conn._insert_df(df, table_name, database, schema)  # noqa: SLF001
 
     # mocks https://docs.snowflake.com/en/sql-reference/sql/copy-into-table.html#output
     mock_copy_results = [("fakesnow/file0.txt", "LOADED", count, count, 1, 0, None, None, None, None)]

tests/test_fakes.py

@@ -491,3 +491,21 @@ def test_write_pandas(conn: snowflake.connector.SnowflakeConnection):
         cur.execute("select id, first_name, last_name from customers")
 
         assert cur.fetchall() == [(1, "Jenny", "P"), (2, "Jasper", "M")]
+
+
+def test_write_pandas_partial_columns(conn: snowflake.connector.SnowflakeConnection):
+    with conn.cursor() as cur:
+        cur.execute("create table customers (ID int, FIRST_NAME varchar, LAST_NAME varchar)")
+
+        df = pd.DataFrame.from_records(
+            [
+                {"ID": 1, "FIRST_NAME": "Jenny"},
+                {"ID": 2, "FIRST_NAME": "Jasper"},
+            ]
+        )
+        snowflake.connector.pandas_tools.write_pandas(conn, df, "customers")
+
+        cur.execute("select id, first_name, last_name from customers")
+
+        # columns not in dataframe will receive their default value
+        assert cur.fetchall() == [(1, "Jenny", None), (2, "Jasper", None)]