issue #104 - fix BillingPeriod date calculation; WIP fixing acceptanc…

…e tests for changes

biweeklybudget/interest.py

@@ -330,16 +330,24 @@ def __init__(self, end_date, start_date=None):
         self._period_for_date = end_date
         if start_date is None:
             if end_date.day < 15:
-                self._start_date = end_date.replace(day=1)
+                # if end date is < 15, period is month before end_date
+                self._end_date = (end_date.replace(day=1) - timedelta(days=1))
+                self._start_date = self._end_date.replace(day=1)
             else:
-                self._start_date = (end_date + relativedelta(
-                    months=1
-                )).replace(day=1)
+                # if end date >= 15, period is month containing end_date
+                self._start_date = end_date.replace(day=1)
+                self._end_date = end_date.replace(
+                    day=(monthrange(
+                        end_date.year, end_date.month
+                    )[1])
+                )
         else:
             self._start_date = start_date
-        self._end_date = self._start_date.replace(
-            day=(monthrange(self._start_date.year, self._start_date.month)[1])
-        )
+            self._end_date = self._start_date.replace(
+                day=(monthrange(
+                    self._start_date.year, self._start_date.month
+                )[1])
+            )
 
     @property
     def start_date(self):

biweeklybudget/tests/acceptance/test_interest.py

@@ -41,7 +41,7 @@
 
 from biweeklybudget.tests.acceptance_helpers import AcceptanceHelper
 from biweeklybudget.interest import (
-    InterestHelper, CCStatement, BillingPeriodNumDays, AdbCompoundedDaily,
+    InterestHelper, CCStatement, _BillingPeriod, AdbCompoundedDaily,
     MinPaymentAmEx, MinPaymentDiscover
 )
 from biweeklybudget.models import Account
@@ -66,10 +66,9 @@ def test_init_statements(self, testdb):
         assert sorted(res.keys()) == [3, 4]
         s3 = res[3]
         assert isinstance(s3, CCStatement)
-        assert isinstance(s3._billing_period, BillingPeriodNumDays)
-        assert s3._billing_period.num_days == 30
-        assert s3._billing_period._end_date == date(2017, 7, 27)
-        assert s3._billing_period._start_date == date(2017, 6, 27)
+        assert isinstance(s3._billing_period, _BillingPeriod)
+        assert s3._billing_period._end_date == date(2017, 7, 31)
+        assert s3._billing_period._start_date == date(2017, 7, 1)
         assert isinstance(s3._interest_cls, AdbCompoundedDaily)
         assert s3._interest_cls.apr == Decimal('0.0100')
         assert isinstance(s3._min_pay_cls, MinPaymentAmEx)
@@ -80,10 +79,9 @@ def test_init_statements(self, testdb):
         assert s3._interest_amt == Decimal('16.25')
         s4 = res[4]
         assert isinstance(s4, CCStatement)
-        assert isinstance(s4._billing_period, BillingPeriodNumDays)
-        assert s4._billing_period.num_days == 30
-        assert s4._billing_period._end_date == date(2017, 7, 26)
-        assert s4._billing_period._start_date == date(2017, 6, 26)
+        assert isinstance(s4._billing_period, _BillingPeriod)
+        assert s4._billing_period._end_date == date(2017, 7, 31)
+        assert s4._billing_period._start_date == date(2017, 7, 1)
         assert isinstance(s4._interest_cls, AdbCompoundedDaily)
         assert s4._interest_cls.apr == Decimal('0.1000')
         assert isinstance(s4._min_pay_cls, MinPaymentDiscover)

biweeklybudget/tests/unit/test_interest.py

@@ -425,11 +425,11 @@ class TestBillingPeriod(object):
 
     def test_init(self):
         cls = _BillingPeriod(date(2017, 1, 20))
-        assert cls._end_date == date(2017, 2, 28)
-        assert cls._start_date == date(2017, 2, 1)
-        cls = _BillingPeriod(date(2017, 1, 5))
         assert cls._end_date == date(2017, 1, 31)
         assert cls._start_date == date(2017, 1, 1)
+        cls = _BillingPeriod(date(2017, 1, 5))
+        assert cls._end_date == date(2016, 12, 31)
+        assert cls._start_date == date(2016, 12, 1)
 
     def test_description(self):
         cls = _BillingPeriod(date(2017, 1, 20))
@@ -1196,23 +1196,23 @@ def test_cc_one_pay_min(self):
             MinPaymentMethod(),
             [self.stmt_cc_one]
         )
-        assert res == [(28, Decimal('962.9988625702411101133192793'))]
+        assert res == [(28, Decimal('963.0134129663259560304255428'))]
 
     def test_cc_two_pay_min(self):
         res = calculate_payoffs(
             MinPaymentMethod(),
             [self.stmt_cc_two]
         )
-        assert res == [(162, Decimal('8664.861877369277471400473622'))]
+        assert res == [(162, Decimal('8666.307398441498144465534193'))]
 
     def test_combined_pay_min(self):
         res = calculate_payoffs(
             MinPaymentMethod(),
             [self.stmt_cc_one, self.stmt_cc_two]
         )
         assert res == [
-            (28, Decimal('962.9988625702411101133192793')),
-            (162, Decimal('8664.861877369277471400473622'))
+            (28, Decimal('963.0134129663259560304255428')),
+            (162, Decimal('8666.307398441498144465534193'))
         ]
 
     def test_combined_pay_lowest_ir(self):
@@ -1221,8 +1221,8 @@ def test_combined_pay_lowest_ir(self):
             [self.stmt_cc_one, self.stmt_cc_two]
         )
         assert res == [
-            (21, Decimal('960.9178327498502165965138131')),
-            (56, Decimal('6988.237124948955044765363412'))
+            (21, Decimal('960.9358774264952173529404070')),
+            (56, Decimal('6989.409862579702020000831215'))
         ]
 
     def test_combined_pay_lowest_bal(self):
@@ -1231,8 +1231,8 @@ def test_combined_pay_lowest_bal(self):
             [self.stmt_cc_one, self.stmt_cc_two]
         )
         assert res == [
-            (21, Decimal('960.9178327498502165965138131')),
-            (56, Decimal('6988.237124948955044765363412'))
+            (21, Decimal('960.9358774264952173529404070')),
+            (56, Decimal('6989.409862579702020000831215'))
         ]
 
     def test_combined_pay_highest_ir(self):
@@ -1241,8 +1241,8 @@ def test_combined_pay_highest_ir(self):
             [self.stmt_cc_one, self.stmt_cc_two]
         )
         assert res == [
-            (28, Decimal('962.9988625702411101133192793')),
-            (55, Decimal('6956.345228060182432444990377'))
+            (28, Decimal('963.0134129663259560304255428')),
+            (55, Decimal('6957.598431791986846666601930'))
         ]
 
     def test_combined_pay_highest_bal(self):
@@ -1251,8 +1251,8 @@ def test_combined_pay_highest_bal(self):
             [self.stmt_cc_one, self.stmt_cc_two]
         )
         assert res == [
-            (28, Decimal('962.9988625702411101133192793')),
-            (55, Decimal('6956.345228060182432444990377'))
+            (28, Decimal('963.0134129663259560304255428')),
+            (55, Decimal('6957.598431791986846666601930'))
         ]