test(statement): cover dictionary-encoded bind parameter columns

adbc_drivers_validation/tests/statement.py

@@ -121,6 +121,45 @@ def test_parameter_execute(
             result = pyarrow.RecordBatchReader._import_from_c(handle.address).read_all()
         assert result[0].to_pylist() == [2, 3, 4, 5]
 
+    @pytest.mark.requires_features(["statement_bind"])
+    def test_parameter_dictionary_encoded(
+        self,
+        driver: model.DriverQuirks,
+        conn: adbc_driver_manager.dbapi.Connection,
+        sample_table: str,
+    ) -> None:
+        # Dictionary encoding is an encoding of the same logical values, not
+        # a different logical type (Arrow columnar format, "Dictionary-encoded
+        # Layout").  A driver that binds string parameters should also accept
+        # a dictionary-encoded string column (what pandas produces for
+        # categoricals), decoding it if the database has no equivalent.
+        id_ = driver.quote_identifier("id")
+        value = driver.quote_identifier("value")
+        ids = pyarrow.array([7101, 7102, 7103], type=pyarrow.int64())
+        values = pyarrow.array(
+            ["apple", "banana", None], type=pyarrow.string()
+        ).dictionary_encode()
+        parameters = pyarrow.RecordBatch.from_arrays([ids, values], names=["0", "1"])
+        with conn.cursor() as cursor:
+            cursor.adbc_statement.set_sql_query(
+                f"INSERT INTO {sample_table} ({id_}, {value}) "
+                f"VALUES ({driver.bind_parameter(1)}, {driver.bind_parameter(2)})"
+            )
+            # Prepare before Bind: some drivers (e.g. the Go FlightSQL
+            # driver) require it, and prepare-first works everywhere.
+            cursor.adbc_statement.prepare()
+            cursor.adbc_statement.bind(parameters)
+            cursor.adbc_statement.execute_update()
+
+        with conn.cursor() as cursor:
+            cursor.adbc_statement.set_sql_query(
+                f"SELECT {value} FROM {sample_table} "
+                f"WHERE {id_} IN (7101, 7102, 7103) ORDER BY {id_}"
+            )
+            handle, _ = cursor.adbc_statement.execute_query()
+            result = pyarrow.RecordBatchReader._import_from_c(handle.address).read_all()
+        assert result[0].to_pylist() == ["apple", "banana", None]
+
     def test_parameter_schema(
         self, driver: model.DriverQuirks, conn: adbc_driver_manager.dbapi.Connection
     ) -> None: