Add a regression test for time and datetime cross validation

Also fixes the none check in time validation

Author: vidartf

python/ipywidgets/ipywidgets/widgets/tests/test_widget_datetime.py

@@ -6,7 +6,9 @@
 
 import pytest
 
+from contextlib import nullcontext
 import datetime
+import itertools
 
 import pytz
 from traitlets import TraitError
@@ -40,6 +42,44 @@ def test_datetime_validate_value_none():
     assert w.value is None
 
 
+def _permuted_dts():
+    ret = []
+    combos = list(itertools.product([None, dt_1442, dt_2002, dt_2056], repeat=3))
+    for vals in combos:
+        expected = vals[0]
+        if vals[1] and vals[2] and vals[1] > vals[2]:
+            expected = TraitError
+        elif vals[0] is None:
+            pass
+        elif vals[1] and vals[1] > vals[0]:
+            expected = vals[1]
+        elif vals[2] and vals[2] < vals[0]:
+            expected = vals[2]
+        ret.append(vals + (expected,))
+    return ret
+
+
+@pytest.mark.parametrize(
+    "input_value,input_min,input_max,expected",
+    _permuted_dts()
+)
+def test_datetime_cross_validate_value_min_max(
+    input_value,
+    input_min,
+    input_max,
+    expected,
+):
+    w = DatetimePicker(value=dt_2002, min=dt_2002, max=dt_2002)
+    should_raise = expected is TraitError
+    with pytest.raises(expected) if should_raise else nullcontext():
+        with w.hold_trait_notifications():
+            w.value = input_value
+            w.min = input_min
+            w.max = input_max
+    if not should_raise:
+        assert w.value is expected
+
+
 def test_datetime_validate_value_vs_min():
     dt = dt_2002
     dt_min = datetime.datetime(2019, 1, 1, tzinfo=pytz.utc)

python/ipywidgets/ipywidgets/widgets/tests/test_widget_time.py

@@ -24,6 +24,20 @@ def test_time_creation_value():
     assert w.value is t
 
 
+def test_time_cross_validate_value_min_max():
+    w = TimePicker(value=datetime.time(2), min=datetime.time(2), max=datetime.time(2))
+    with w.hold_trait_notifications():
+        w.value = None
+        w.min = datetime.time(4)
+        w.max = datetime.time(6)
+    assert w.value is None
+    with w.hold_trait_notifications():
+        w.value = datetime.time(4)
+        w.min = None
+        w.max = None
+    assert w.value == datetime.time(4)
+
+
 def test_time_validate_value_none():
     t = datetime.time(13, 37, 42, 7)
     t_min = datetime.time(2)

python/ipywidgets/ipywidgets/widgets/widget_time.py

@@ -63,6 +63,8 @@ class TimePicker(DescriptionWidget, ValueWidget, CoreWidget):
     def _validate_value(self, proposal):
         """Cap and floor value"""
         value = proposal["value"]
+        if value is None:
+            return value
         if self.min and self.min > value:
             value = max(value, self.min)
         if self.max and self.max < value:
@@ -73,6 +75,8 @@ def _validate_value(self, proposal):
     def _validate_min(self, proposal):
         """Enforce min <= value <= max"""
         min = proposal["value"]
+        if min is None:
+            return min
         if self.max and min > self.max:
             raise TraitError("Setting min > max")
         if self.value and min > self.value:
@@ -83,6 +87,8 @@ def _validate_min(self, proposal):
     def _validate_max(self, proposal):
         """Enforce min <= value <= max"""
         max = proposal["value"]
+        if max is None:
+            return max
         if self.min and max < self.min:
             raise TraitError("setting max < min")
         if self.value and max < self.value: