[shipping rule] validations and test cases
diff --git a/accounts/doctype/shipping_rule/shipping_rule.py b/accounts/doctype/shipping_rule/shipping_rule.py
index 5ed4ed3..8714865 100644
--- a/accounts/doctype/shipping_rule/shipping_rule.py
+++ b/accounts/doctype/shipping_rule/shipping_rule.py
@@ -3,23 +3,80 @@
 from __future__ import unicode_literals
 import webnotes
 from webnotes import _, msgprint
+from webnotes.utils import flt, fmt_money
+from webnotes.model.controller import DocListController
+from setup.utils import get_company_currency
 
-class DocType:
+class OverlappingConditionError(webnotes.ValidationError): pass
+class FromGreaterThanToError(webnotes.ValidationError): pass
+class ManyBlankToValuesError(webnotes.ValidationError): pass
+
+class DocType(DocListController):
 	def __init__(self, d, dl):
 		self.doc, self.doclist = d, dl
 		
 	def validate(self):
-		self.validate_to_value_of_shipping_rule_conditions()
+		self.shipping_rule_conditions = self.doclist.get({"parentfield": "shipping_rule_conditions"})
+		self.validate_from_to_values()
+		self.sort_shipping_rule_conditions()
 		self.validate_overlapping_shipping_rule_conditions()
 		
+	def validate_from_to_values(self):
+		zero_to_values = []
 		
-	def validate_to_value_of_shipping_rule_conditions(self):
-		"""check if more than two or more rows has To Value = 0"""
-		shipping_rule_conditions_with_0_to_value = self.doclist.get({
-			"parentfield": "shipping_rule_conditions", "to_value": ["in", [0, None]]})
-		if len(shipping_rule_conditions_with_0_to_value) >= 2:
-			msgprint(_('''There can only be one shipping rule with 0 or blank value for "To Value"'''),
-				raise_exception=True)
+		for d in self.shipping_rule_conditions:
+			self.round_floats_in(d)
+			
+			# values cannot be negative
+			self.validate_value("from_value", ">=", 0.0, d)
+			self.validate_value("to_value", ">=", 0.0, d)
+			
+			if d.to_value == 0:
+				zero_to_values.append(d)
+			elif d.from_value >= d.to_value:
+				msgprint(_("Error") + ": " + _("Row") + " # %d: " % d.idx + 
+					_("From Value should be less than To Value"),
+					raise_exception=FromGreaterThanToError)
+		
+		# check if more than two or more rows has To Value = 0
+		if len(zero_to_values) >= 2:
+			msgprint(_('''There can only be one Shipping Rule Condition with 0 or blank value for "To Value"'''),
+				raise_exception=ManyBlankToValuesError)
 				
+	def sort_shipping_rule_conditions(self):
+		"""Sort Shipping Rule Conditions based on increasing From Value"""
+		self.shipping_rules_conditions = sorted(self.shipping_rule_conditions, key=lambda d: flt(d.from_value))
+		for i, d in enumerate(self.shipping_rule_conditions):
+			d.idx = i + 1
+
 	def validate_overlapping_shipping_rule_conditions(self):
-		pass
\ No newline at end of file
+		def overlap_exists_between((x1, x2), (y1, y2)):
+			"""
+				(x1, x2) and (y1, y2) are two ranges
+				if condition x = 100 to 300
+				then condition y can only be like 50 to 99 or 301 to 400
+				hence, non-overlapping condition = (x1 <= x2 < y1 <= y2) or (y1 <= y2 < x1 <= x2)
+			"""
+			separate = (x1 <= x2 < y1 <= y2) or (y1 <= y2 < x1 <= x2)
+			return (not separate)
+		
+		overlaps = []
+		for i in xrange(0, len(self.shipping_rule_conditions)):
+			for j in xrange(i+1, len(self.shipping_rule_conditions)):
+				d1, d2 = self.shipping_rule_conditions[i], self.shipping_rule_conditions[j]
+				if d1.fields != d2.fields:
+					# in our case, to_value can be zero, hence pass the from_value if so
+					range_a = (d1.from_value, d1.to_value or d1.from_value)
+					range_b = (d2.from_value, d2.to_value or d2.from_value)
+					if overlap_exists_between(range_a, range_b):
+						overlaps.append([d1, d2])
+		
+		if overlaps:
+			company_currency = get_company_currency(self.doc.company)
+			msgprint(_("Error") + ": " + _("Overlapping Conditions found between") + ":")
+			messages = []
+			for d1, d2 in overlaps:
+				messages.append("%s-%s = %s " % (d1.from_value, d1.to_value, fmt_money(d1.shipping_amount, currency=company_currency)) + 
+					_("and") + " %s-%s = %s" % (d2.from_value, d2.to_value, fmt_money(d2.shipping_amount, currency=company_currency)))
+					  	
+			msgprint("\n".join(messages), raise_exception=OverlappingConditionError)
\ No newline at end of file
diff --git a/accounts/doctype/shipping_rule/test_shipping_rule.py b/accounts/doctype/shipping_rule/test_shipping_rule.py
new file mode 100644
index 0000000..ff217bc
--- /dev/null
+++ b/accounts/doctype/shipping_rule/test_shipping_rule.py
@@ -0,0 +1,66 @@
+import webnotes
+import unittest
+from accounts.doctype.shipping_rule.shipping_rule import FromGreaterThanToError, ManyBlankToValuesError, OverlappingConditionError
+
+class TestShippingRule(unittest.TestCase):
+	def test_from_greater_than_to(self):
+		shipping_rule = webnotes.bean(copy=test_records[0])
+		shipping_rule.doclist[1].from_value = 101
+		self.assertRaises(FromGreaterThanToError, shipping_rule.insert)
+		
+	def test_many_zero_to_values(self):
+		shipping_rule = webnotes.bean(copy=test_records[0])
+		shipping_rule.doclist[1].to_value = 0
+		self.assertRaises(ManyBlankToValuesError, shipping_rule.insert)
+		
+	def test_overlapping_conditions(self):
+		for range_a, range_b in [
+			((50, 150), (0, 100)),
+			((50, 150), (100, 200)),
+			((50, 150), (75, 125)),
+			((50, 150), (25, 175)),
+			((50, 150), (50, 150)),
+		]:
+			shipping_rule = webnotes.bean(copy=test_records[0])
+			shipping_rule.doclist[1].from_value = range_a[0]
+			shipping_rule.doclist[1].to_value = range_a[1]
+			shipping_rule.doclist[2].from_value = range_b[0]
+			shipping_rule.doclist[2].to_value = range_b[1]
+			self.assertRaises(OverlappingConditionError, shipping_rule.insert)
+
+test_records = [
+	[
+		{
+			"doctype": "Shipping Rule",
+			"calculate_based_on": "Amount",
+			"company": "_Test Company",
+			"account": "_Test Account Shipping Charges - _TC",
+			"cost_center": "_Test Cost Center - _TC"
+		},
+		{
+			"doctype": "Shipping Rule Condition",
+			"parentfield": "shipping_rule_conditions",
+			"from_value": 0,
+			"to_value": 100,
+			"shipping_amount": 50.0
+		},
+		{
+			"doctype": "Shipping Rule Condition",
+			"parentfield": "shipping_rule_conditions",
+			"from_value": 101,
+			"to_value": 200,
+			"shipping_amount": 100.0
+		},
+		{
+			"doctype": "Shipping Rule Condition",
+			"parentfield": "shipping_rule_conditions",
+			"from_value": 201,
+			"shipping_amount": 0.0
+		},
+		{
+			"doctype": "For Territory",
+			"parentfield": "valid_for_territories",
+			"territory": "_Test Territory"
+		}
+	]
+]
\ No newline at end of file