adding unit tests

Author: yanismnsr

.DS_Store

@@ -103,7 +103,7 @@ def find_combinations (list, k) :
 
     n = len(list)
     combinations = []
-    if k < 0 and k > n :
+    if k < 0 or k > n :
         raise ValueError ("k must be equal to 0 or positive and less than or equal to n")
     if k == 0 :
         return [[]]

src/combinations/combinations.py

@@ -0,0 +1,40 @@
+import unittest
+import math
+from src.combinations import combinations
+
+def _combinationsNumber (n, k) :
+    return math.factorial(n) / (math.factorial(k) * math.factorial(n - k))
+
+class CombinationsTest(unittest.TestCase) :
+
+    def test_numberOfCombinations (self): 
+        list = [2,7,9,3,5,6,8,4,1]
+        n = len(list)
+        k = 3
+        combs = combinations.find_combinations(list, k)
+        self.assertEqual(len(combs), _combinationsNumber(n, k))
+        k = 0
+        combs = combinations.find_combinations(list, k)
+        self.assertEqual(len(combs), 1)
+        k = n
+        combs = combinations.find_combinations(list, k)
+        self.assertEqual(len(combs), 1)
+
+    def test_combinationsLength (self) :
+        list = [2,7,9,3,5,6,8,4,1]
+        n = len(list)
+        k = 3
+        combs = combinations.find_combinations(list, k)
+        for comb in combs :
+            self.assertEqual(len(comb), k)
+    
+    def test_raisingErrors (self) :
+        with self.assertRaises(ValueError) :
+            combinations.find_combinations([], -1)
+        with self.assertRaises(ValueError) :
+            combinations.find_combinations([1,2,3], 4)
+        
+
+
+if __name__ == '__main__':
+    unittest.main()