fix: right tests for value errors and zero len argument

excel2py/excel_functions.py

@@ -8,6 +8,7 @@
 import numbers
 from collections import Iterable
 from functools import reduce
+import excel2py.excel_functions as ef
 from excel2py.ex_datetime import ex_datetime, to_excel_number
 
 
@@ -202,6 +203,21 @@ def VLOOKUP(value, table, column, range_lookup=True):
         return table[-1][column-1]
     return None
 
+
+def RIGHT(x, len=1):
+    """
+    RIGHT returns the last character or characters in a text string, 
+    based on the number of characters you specify.
+    :param x: the text
+    :param len: the number of character specified, default is 1
+    :return : the last character or characters 
+    """
+    if isinstance(len, (str, list, tuple, bool)) or len < 0:
+        raise ValueError("ValueError exception thrown") 
+    elif len != 0:
+        return x[-len:]
+    return ''
+
 #
 # dt = ex_datetime(2018, 7, 5)
 # print(MIN(dt))

tests/test_excel_functions.py

@@ -169,5 +169,48 @@ def test_ok(self):
                 self.assertEqual(ef.INT(val), expect)
 
 
+# RIGHT test
+class TestRight(unittest.TestCase):
+    def test_with_optional_value(self):
+        """
+        Test to extract characters based on the second argument
+        """
+        expect = "cel"
+        result = ef.RIGHT("Excel", 3)
+        self.assertEqual(expect, result)
+
+    def test_with_no_optional_value(self):
+        """
+        Test to extract characters if no second argument is passed
+        """
+        expect = 'l'
+        result = ef.RIGHT("Excel")
+        self.assertEqual(expect, result)
+
+    def test_with_zero_as_len(self):
+        """
+        Test to return any empty string if 0 is passed as the len
+        """
+        result = ef.RIGHT("ABC",0)
+        self.assertEqual('',result)
+
+    def test_value_errors(self):
+        """
+        Throw a value error if the len is a string or a negative value
+        """
+        with self.assertRaises(ValueError):
+            ef.RIGHT("ABC","len")
+        with self.assertRaises(ValueError):
+            ef.RIGHT("ABC",-1)
+        with self.assertRaises(ValueError):
+            ef.RIGHT("ABC",True)
+        with self.assertRaises(ValueError):
+            ef.RIGHT("ABC",[5,10,15])
+        with self.assertRaises(ValueError):
+            ef.RIGHT("ABC",(25,30,35))
+
+
+
+
 if __name__ == "__main__":
     unittest.main()