From f46a1110fbdf66af3545c657b889b632b824570c Mon Sep 17 00:00:00 2001
From: bytebutcher <thomas.engel.web@gmail.com>
Date: Tue, 4 Jul 2023 11:51:56 +0200
Subject: [PATCH] #5 Allow to unset functions in DisplayFilter

---
 pydictdisplayfilter/display_filters.py | 11 +++---
 tests/test_dict_display_filter.py      | 52 ++++++++++++++++++++++++++
 2 files changed, 57 insertions(+), 6 deletions(-)

diff --git a/pydictdisplayfilter/display_filters.py b/pydictdisplayfilter/display_filters.py
index f8945c3..e498aa2 100644
--- a/pydictdisplayfilter/display_filters.py
+++ b/pydictdisplayfilter/display_filters.py
@@ -45,16 +45,15 @@ def __init__(self,
         :param evaluator: The evaluator used to evaluate the expressions. If no evaluator is specified the
                           DefaultEvaluator is used.
         """
-        functions = functions if functions else {
+        self._slicer_factory = SlicerFactory(slicers)
+        self._evaluator = evaluator if evaluator else DefaultEvaluator()
+        self._functions = functions if functions is not None else {
             "len": lambda value: len(value),
             "lower": lambda value: value.lower(),
             "upper": lambda value: value.upper()
         }
-        self._slicer_factory = SlicerFactory(slicers)
-        self._evaluator = evaluator if evaluator else DefaultEvaluator()
-        self._functions = functions or []
-        self._field_names = field_names or []
-        self._display_filter_parser = DisplayFilterParser(field_names=field_names, functions=functions)
+        self._field_names = field_names if field_names is not None else []
+        self._display_filter_parser = DisplayFilterParser(field_names=self._field_names, functions=self._functions)
 
     def _get_item_value(self, expression, item) -> str:
         """
diff --git a/tests/test_dict_display_filter.py b/tests/test_dict_display_filter.py
index 121632b..092f18b 100644
--- a/tests/test_dict_display_filter.py
+++ b/tests/test_dict_display_filter.py
@@ -19,6 +19,7 @@
 from parameterized import parameterized
 
 from pydictdisplayfilter.display_filters import DictDisplayFilter
+from pydictdisplayfilter.exceptions import ParserError
 
 
 class TestDictDisplayFilter(unittest.TestCase):
@@ -266,3 +267,54 @@ def test_net_dict_display_filter_returns_correct_number_of_items(self, display_f
     def test_mixed_data_display_filter_returns_correct_number_of_items(self, display_filter, no_items):
         items = list(DictDisplayFilter(self.mixed_data).filter(display_filter))
         self.assertEqual(len(items), no_items)
+
+    @parameterized.expand([
+        # Fields
+        ["lower(value) == foobar", 2],
+        ["upper(value) == FOOBAR", 2],
+        ["upper(value) ~= FOO", 3],
+        ["lower(value) ~= foo", 3],
+        ["len(value) == 6", 2],
+        ["len(value) == 3", 2],
+    ])
+    def test_functions_default(self, display_filter, no_items):
+        data = [{'value': 'foobar'}, {'value': 'FOOBAR'}, {'value': 'FOO'}, {'value': 'BAR'}]
+        items = list(DictDisplayFilter(data).filter(display_filter))
+        self.assertEqual(len(items), no_items)
+
+    @parameterized.expand([
+        # Fields
+        ["ltrim(value) == foobar"],
+        ["rtrim(value) == foobar"],
+        ["trim(value) == foobar"],
+    ])
+    def test_functions_undefined_raises_parser_error(self, display_filter):
+        data = [{'value': 'foobar'}, {'value': 'FOOBAR'}, {'value': 'FOO'}, {'value': 'BAR'}]
+        self.assertRaises(ParserError, lambda: list(DictDisplayFilter(data).filter(display_filter)))
+
+    @parameterized.expand([
+        # Fields
+        ["value == foobar", 0],
+        ["ltrim(value) == foobar", 1],
+        ["rtrim(value) == foobar", 1],
+        ["trim(value) == foobar", 3]
+    ])
+    def test_functions_custom(self, display_filter, no_items):
+        data = [{'value': ' foobar'}, {'value': ' foobar '}, {'value': 'foobar '}]
+        functions = {
+            'ltrim': lambda v: v.lstrip(),
+            'rtrim': lambda v: v.rstrip(),
+            'trim': lambda v: v.strip()
+        }
+        items = list(DictDisplayFilter(data, functions=functions).filter(display_filter))
+        self.assertEqual(len(items), no_items)
+
+    @parameterized.expand([
+        # Fields
+        ["lower(value) == foobar"],
+        ["upper(value) == FOOBAR"],
+        ["len(value) == 6"],
+    ])
+    def test_functions_none(self, display_filter):
+        data = [{'value': 'foobar'}, {'value': 'FOOBAR'}, {'value': 'FOO'}, {'value': 'BAR'}]
+        self.assertRaises(ParserError, lambda: list(DictDisplayFilter(data, functions={}).filter(display_filter)))