Fix CI and app test

Author: datapythonista

pandas/core/frame.py

@@ -3574,6 +3574,10 @@ def to_iceberg(
         snapshot_properties : dict of {str: str}, optional
             Custom properties to be added to the snapshot summary
 
+        Returns
+        -------
+        None
+
         See Also
         --------
         read_iceberg : Read an Apache Iceberg table.
@@ -3582,7 +3586,7 @@ def to_iceberg(
         Examples
         --------
         >>> df = pd.DataFrame(data={"col1": [1, 2], "col2": [4, 3]})
-        >>> df.to_iceberg("my_table", catalog_name="my_catalog")
+        >>> df.to_iceberg("my_table", catalog_name="my_catalog")  # doctest: +SKIP
         """
         from pandas.io.iceberg import to_iceberg
 

pandas/io/iceberg.py

@@ -1,13 +1,19 @@
 from typing import (
+    TYPE_CHECKING,
     Any,
 )
 
 from pandas.compat._optional import import_optional_dependency
 
 from pandas import DataFrame
 
+if TYPE_CHECKING:
+    from pyiceberg.catalog import Catalog  # noqa: TC004
 
-def _get_catalog(catalog_name: str | None, catalog_properties: dict[str, Any] | None):
+
+def _get_catalog(
+    catalog_name: str | None, catalog_properties: dict[str, Any] | None
+) -> Catalog:
     pyiceberg_catalog = import_optional_dependency("pyiceberg.catalog")
     if catalog_properties is None:
         catalog_properties = {}
@@ -105,7 +111,7 @@ def to_iceberg(
     catalog_properties: dict[str, Any] | None = None,
     location: str | None = None,
     snapshot_properties: dict[str, str] | None = None,
-):
+) -> None:
     """
     Write a DataFrame to an Apache Iceberg table.
 
@@ -128,11 +134,6 @@ def to_iceberg(
     --------
     read_iceberg : Read an Apache Iceberg table.
     DataFrame.to_parquet : Write a DataFrame in Parquet format.
-
-    Examples
-    --------
-    >>> df = pd.DataFrame(data={"col1": [1, 2], "col2": [4, 3]})
-    >>> df.to_iceberg("my_table", catalog_name="my_catalog")
     """
     pa = import_optional_dependency("pyarrow")
 

pandas/tests/io/test_iceberg.py

@@ -177,3 +177,25 @@ def test_write_by_catalog_name(self, catalog):
             catalog_name=catalog.name,
         )
         tm.assert_frame_equal(result, df)
+
+    def test_write_existing_table(self, catalog):
+        original = read_iceberg(
+            "ns.my_table",
+            catalog_properties={"uri": catalog.uri},
+        )
+        new = pd.DataFrame(
+            {
+                "A": [4, 5],
+                "B": ["bar", "foobar"],
+            }
+        )
+        new.to_iceberg(
+            "ns.my_table",
+            catalog_properties={"uri": catalog.uri},
+            location=catalog.warehouse,
+        )
+        result = read_iceberg(
+            "ns.my_table",
+            catalog_properties={"uri": catalog.uri},
+        )
+        tm.assert_frame_equal(result, pd.concat([original, new]))