Allow Falsey values for IsNumber validator

We should use Required() instead to ensure data is present, if that's the
desired behavior

atst/forms/validators.py

@@ -36,10 +36,11 @@ def DateRange(lower_bound=None, upper_bound=None, message=None):
 
 def IsNumber(message=translate("forms.validators.is_number_message")):
     def _is_number(form, field):
-        try:
-            int(field.data)
-        except (ValueError, TypeError):
-            raise ValidationError(message)
+        if field.data:
+            try:
+                int(field.data)
+            except (ValueError, TypeError):
+                raise ValidationError(message)
 
     return _is_number
 

tests/forms/test_validators.py

@@ -11,7 +11,7 @@ class TestIsNumber:
         dummy_field.data = valid
         validator(dummy_form, dummy_field)
 
-    @pytest.mark.parametrize("invalid", ["12.1", "two", "", None])
+    @pytest.mark.parametrize("invalid", ["12.1", "two"])
     def test_IsNumber_rejects_anything_else(self, invalid, dummy_form, dummy_field):
         validator = IsNumber()
         dummy_field.data = invalid