#55 Fixed the empty input bug (#57)

* #55 Fixed the empty input bug

* #55 Updated poetry.lock

* #55 Updated poetry.lock

* #55 Fixed the pandas append issue

* Apply suggestions from code review

Co-authored-by: Christoph Kuhnke <christoph.kuhnke@exasol.com>

---------

Co-authored-by: Christoph Kuhnke <christoph.kuhnke@exasol.com>

Author: ahsimb

.github/workflows/pytest.yaml

@@ -7,7 +7,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: [ "3.8", "3.10" ]
+        python-version: [ "3.10", "3.11" ]
     runs-on: ubuntu-latest
 
     steps:

doc/changes/unreleased.md

@@ -6,4 +6,8 @@ Code name: tbd
 
 ### Bugs
 
-n/a
+* #55: Fixed bug when creating a `StandaloneMockContext` with empty input list
+
+### Features
+
+* #56: Made `script_code_wrapper_function` parameter of the `MockMetaData` optional.

exasol_udf_mock_python/mock_context.py

@@ -1,4 +1,5 @@
 from typing import List, Tuple, Iterator, Iterable, Any, Optional, Union
+from collections.abc import Sized
 from functools import wraps
 
 import pandas as pd
@@ -133,24 +134,30 @@ def emit(self, *args) -> None:
         self._current_context.emit(*args)
 
 
-def get_scalar_input(inp: Any) -> Iterable[Tuple[Any, ...]]:
+def get_scalar_input(inp: Any) -> Iterable[Iterable[Any]]:
     """
     Figures out if the SCALAR parameters are provided as a scalar value or a tuple
     and also if there is a wrapping container around.
-    Unless the parameters are already in a wrapping container returns parameters as a tuple wrapped
-    into a one-item list, e.g [(param1[, param2, ...)]. Otherwise, returns the original input.
+    Unless the parameters are already in a wrapping Sized container, returns parameters as an iterable
+    wrapped into a one-item list, e.g [(param1, [param2, ...])]. Otherwise, returns the original input.
 
     :param  inp:        Input parameters.
     """
 
-    if isinstance(inp, Iterable) and not isinstance(inp, str):
-        row1 = next(iter(inp))
-        if isinstance(row1, Iterable) and not isinstance(row1, str):
-            return inp
-        else:
-            return [inp]
-    else:
-        return [(inp,)]
+    if inp is not None:
+        if (not isinstance(inp, Iterable)) or isinstance(inp, str):
+            return [(inp,)]
+        try:
+            row1 = next(iter(inp))
+            if (not isinstance(row1, Iterable)) or isinstance(row1, str):
+                return [inp]
+            elif not isinstance(inp, Sized):
+                return list(inp)
+            else:
+                return inp
+        except StopIteration:
+            pass
+    return [tuple()]
 
 
 class StandaloneMockContext(UDFContext):
@@ -205,20 +212,18 @@ def get_dataframe(self, num_rows='all', start_col=0):
         columns_ = [column.name for column in self._metadata.input_columns[start_col:]]
 
         i = 0
-        df = None
+        dfs: list[pd.DataFrame] = []
         while num_rows == 'all' or i < num_rows:
-            df_current = pd.DataFrame.from_records(
-                [self._data[start_col:]], columns=columns_)
-            if df is None:
-                df = df_current
-            else:
-                df = df.append(df_current)
+            dfs.append(pd.DataFrame.from_records(
+                [self._data[start_col:]], columns=columns_))
             if not self.next():
                 break
             i += 1
-        if df is not None:
-            df = df.reset_index(drop=True)
-        return df
+        if dfs:
+            df = pd.concat(dfs, ignore_index=True)
+            df.reset_index(inplace=True, drop=True)
+            return df
+        return None
 
     def __getattr__(self, name):
         return None if self._data is None else self._data[self._name_position_map[name]]

exasol_udf_mock_python/mock_meta_data.py

@@ -42,7 +42,8 @@ def __init__(
         self._current_user = current_user
         self._current_schema = current_schema
         self._scope_user = scope_user
-        self._script_code = self._extract_script_code(script_code_wrapper_function)
+        self._script_code = (None if script_code_wrapper_function is None
+                             else self._extract_script_code(script_code_wrapper_function))
         self._connection_id = connection_id
         self._database_name = database_name
         self._database_version = database_version