simulation: Test the divergence with epsilon span on Float Divergence Tester by default

Before:
 Float Divergence Tester does not test the divergence even if Divergence Provider is ON

After:
 Float Divergence Tester test the divergence with epsilon span if Divergence Provider is ON

We needed the following condition to test the divergence on Float Divergence
Tester:

"Divergence Provider is ON"  AND
("Absolute Tolerance has some value"  OR
 "Relative Tolerance has some value" )

However this default behavior was not consistent with other testers, and
difficult to notice from the user interface.
Thus test the divergence by default with the epsilon span which is defined in
FloatDivergenceTester class.

product/ERP5/Document/FloatEquivalenceTester.py

@@ -117,14 +117,23 @@ class FloatEquivalenceTester(Predicate, EquivalenceTesterMixin):
     # XXX we should use appropriate property sheets and getter methods
     # for these properties.
     # Maybe, but beware of default values of quantity when doing so
-    absolute_tolerance_min = self.getProperty('quantity_range_min')
+    tolerance_base = self.getProperty('tolerance_base')
+    # If torelance_base is None, check the divergece with epsilon-span by default
+    # If torelance_base is not None, we can use tolerance_base (absolute has priority)
+    if tolerance_base is None:
+      absolute_tolerance_min = self.getProperty('quantity_range_min') or -epsilon
+    else:
+      absolute_tolerance_min = self.getProperty('quantity_range_min')
     if absolute_tolerance_min is not None and \
        delta < (absolute_tolerance_min or - epsilon):
       return (
         prevision_value, decision_value,
         explanation_start + 'is less than ${value}.',
         getMappingDict(value=absolute_tolerance_min))
-    absolute_tolerance_max = self.getProperty('quantity_range_max')
+    if tolerance_base is None:
+      absolute_tolerance_max = self.getProperty('quantity_range_max') or epsilon 
+    else:
+      absolute_tolerance_max = self.getProperty('quantity_range_max')
     if absolute_tolerance_max is not None and \
        delta > (absolute_tolerance_max or epsilon):
       return (
@@ -132,7 +141,6 @@ class FloatEquivalenceTester(Predicate, EquivalenceTesterMixin):
         explanation_start + 'is larger than ${value}.',
         getMappingDict(value=absolute_tolerance_max))
 
-    tolerance_base = self.getProperty('tolerance_base')
     base = None
     if tolerance_base == 'resource_quantity_precision':
       # Precision of this movement's resource base unit quantity