Fix Bahai conversion

src/convertdate/bahai.py

@@ -8,9 +8,9 @@
 """
 The Bahá'í (Badí) calendar is a solar calendar with 19 months of 19 days.
 
-Every four years, an intercalary period, Ayyam-i-Há, occurs between the 18th and 19th
-months. Dates in this period are returned as month 19, and the month of ‘Alá is always
-reported as month 20.
+An intercalary period, Ayyam-i-Há, occurs between the 18th and 19th months, has
+either four or five days. Dates in this period are returned as month 19, and
+the month of ‘Alá is always reported as month 20.
 
 .. code-block:: python
 
@@ -149,24 +149,14 @@ def to_jd(year, month, day):
 def from_jd(jd):
     '''Calculate Bahai date from Julian day'''
     jd = trunc(jd) + 0.5
-    g = gregorian.from_jd(jd)
-    gy = g[0]
+    gy = gregorian.from_jd(jd)[0]
     n_month, n_day = gregorian_nawruz(gy)
 
-    bstarty = EPOCH_GREGORIAN_YEAR
-
-    if jd <= gregorian.to_jd(gy, n_month, 20):
-        x = 1
-    else:
-        x = 0
-    # verify this next line...
-    bys = gy - (bstarty + (((gregorian.to_jd(gy, 1, 1) <= jd) and x)))
-
-    year = bys + 1
+    x = 1 if jd <= gregorian.to_jd(gy, n_month, 20) else 0
+    year = gy - (EPOCH_GREGORIAN_YEAR + x) + 1
     days = jd - to_jd(year, 1, 1)
-    bld = to_jd(year, n_day - 1, 1)
 
-    if jd >= bld:
+    if jd >= to_jd(year, 20, 1):
         month = 20
     else:
         month = trunc(days / 19) + 1

tests/test_bahai.py

@@ -1,5 +1,6 @@
 # -*- coding: utf-8 -*-
 """Test the Bahá’í calendar"""
+
 import time
 import unittest
 
@@ -9,8 +10,9 @@
 
 
 class TestBahai(CalTestCase):
-
     pairs = {
+        (2016, 2, 26): (172, bahai.AYYAMIHA, 1),
+        (2016, 3, 20): (173, bahai.BAHA, 1),
         (2041, 11, 27): (198, bahai.QAWL, 6),  # ascension of Abdu'l-Bahá 2041
         (2043, 11, 28): (200, bahai.QAWL, 6),  # ascension of Abdu'l-Bahá 2043
         (2038, 3, 1): (194, bahai.ALA, 1),  # beginning of fast 2038
@@ -149,6 +151,17 @@ def test_from_gregorian(self):
         for g, b in self.pairs.items():
             self.assertEqual(b, bahai.from_gregorian(*g))
 
+    def test_near_ayyam_i_ha(self):
+        pairs = [
+            ((2016, 2, 25), (172, 18, 19)),
+            ((2016, 2, 26), (172, 19, 1)),
+            ((2016, 2, 29), (172, 19, 4)),
+            ((2016, 3, 1), (172, 20, 1))
+        ]
+        with self.subTest():
+            for gdate, bdate in pairs:
+                self.assertEqual(bdate, bahai.from_gregorian(*gdate))
+
     def test_month_length(self):
         for x in range(1, 19):
             self.assertEqual(bahai.month_length(2019, x), 19)