From 3873020e154cf5125029f1a919013eb9ba3ec8d7 Mon Sep 17 00:00:00 2001
From: Ava Gaiety Wroten <ava@wroten.me>
Date: Tue, 15 Sep 2020 21:39:04 -0500
Subject: [PATCH] By nine

---
 main.py            | 16 +++++++++++-----
 tests/nine_test.py | 16 ++++++++++++++++
 2 files changed, 27 insertions(+), 5 deletions(-)
 create mode 100644 tests/nine_test.py

diff --git a/main.py b/main.py
index 1488c24..b8c6089 100644
--- a/main.py
+++ b/main.py
@@ -5,16 +5,22 @@ def divide_by_two(num): # Take last digit, divide by two only on that
     return _get_last_digit(num) % 2 == 0
 
 def divide_by_three(num): # Sum each digit in number, then check divisibility of that number
-    num_string = f"{num}"
-    num_sum = 0
-    for digit_char in num_string:
-        num_sum += int(digit_char)
-    return num_sum % 3 == 0
+    return _sum_digits(num) % 3 == 0
 
 def divide_by_five(num): # If last digit is a zero or a five return true
     last_digit = _get_last_digit(num)
     return last_digit == 0 or last_digit == 5
 
+def divide_by_nine(num): # Sum each digit in number, then check divisibility of that number
+    return _sum_digits(num) % 9 == 0
+
 def _get_last_digit(num):
     return int(f"{num}"[-1])
 
+def _sum_digits(num):
+    num_string = f"{num}"
+    num_sum = 0
+    for digit_char in num_string:
+        num_sum += int(digit_char)
+    return num_sum
+
diff --git a/tests/nine_test.py b/tests/nine_test.py
new file mode 100644
index 0000000..e67b53b
--- /dev/null
+++ b/tests/nine_test.py
@@ -0,0 +1,16 @@
+from main import divide_by_nine
+import unittest
+
+class TestDivideByNine(unittest.TestCase):
+    def test_by_1(self):
+        self.assertFalse(divide_by_nine(1))
+    def test_by_3(self):
+        self.assertFalse(divide_by_nine(3))
+    def test_by_9(self):
+        self.assertTrue(divide_by_nine(9))
+    def test_by_10(self):
+        self.assertFalse(divide_by_nine(10))
+    def test_by_18(self):
+        self.assertTrue(divide_by_nine(18))
+    def test_by_362880(self):
+        self.assertTrue(divide_by_nine(362880))