Unit testing using doctest in python

Question

Define a function definition of 'isPalindrome' which checks if given number positive number is palindrome or not and return True and False correspondingly.

• write a doctest which checks the function call 'isPalindrome(121)' returns True.
• write a doctest which checks the function call 'isPalindrome(344)' returns False.
• write a doctest which checks the function call 'isPalindrome(-121)' raises ValueError with an error message as 'x must be positive integer'.
• write a doctest which checks the function call 'isPalindrome('hello')' raises TypeError with an error message as 'x must be an integer'.

I tried below but its giving answer as -

True 4 1 1 4 0

but the expected answer is

True 4 1 1 4 2

#!/bin/python3
import math
import os
import random
import re
import sys
import inspect

# Complete the isPalindrome function below.
def isPalindrome(x):
    # Write your doctests below.
    """
    >>> isPalindrome(121)
    True
    >>> isPalindrome(344)
    False
    >>> isPalindrome(-121)
    ValueError: x must be positive integer.
    >>> isPalindrome("hello")
    TypeError: x must be integer.
    """  

    # Write the functionality below
    try:
        x = int(x)
        temp=x
        rev=0
        if(x>0):
            while(x>0):
                dig=x%10
                rev=rev*10+dig
                x=x//10
            if(temp==rev):
                return True
            else:
                return False
        elif(x<0):
            raise TypeError
        else:
            raise ValueError
    except ValueError:
        raise ValueError("x must be positive integer")
    except TypeError:
        raise TypeError("x must be an integer")


if __name__ == '__main__':
    fptr = open(os.environ['OUTPUT_PATH'], 'w')

    x = input()

    if x.isdigit():
        x = int(x)

    res = isPalindrome(x)

    doc = inspect.getdoc(isPalindrome)

    func_count = len(re.findall(r'isPalindrome', doc))
    true_count = len(re.findall(r'True', doc))
    false_count = len(re.findall(r'False', doc))
    pp_count = len(re.findall(r'>>>', doc))
    trace_count = len(re.findall(r'Traceback', doc))

    fptr.write(str(res)+'\n')
    fptr.write(str(func_count)+'\n')
    fptr.write(str(true_count)+'\n')
    fptr.write(str(false_count)+'\n')
    fptr.write(str(pp_count) + '\n')
    fptr.write(str(trace_count) + '\n')

    fptr.close()

Please suggest

Answer 1

In doctest inorder to detect an exception it needs two keywords : Traceback and the ExceptionName.

for example: If your block raises a ValueError, The test case you provide in doctest file should have a Traceback line and the second line next to it should have the Exception name with its custom message(if any).

The following is the correct way to write the test code:

def isPalindrome(x):
    # Write the doctests:
    """
    >>>isPalindrome(121)
    True
    >>>isPalindrome(344)
    False
    >>>isPalindrome(-121)
    Traceback (most recent call last):
    ValueError : x must be a positive integer
    >>>isPalindrome("hello")
    Traceback (most recent call last):
    TypeError : x must be an integer
    """
    # Write the functionality:
    x = int(x)
    temp=x
    rev=0
    if(x>0):
        while(x>0):
            dig=x%10
            rev=rev*10+dig
            x=x//10
        if(temp==rev):
            return True
        else:
            return False
        
    
if __name__ == '__main__':
    fptr = open(os.environ['OUTPUT_PATH'], 'w')

    x = input()
    
    if x.isdigit():
        x = int(x)

    res = isPalindrome(x)
    
    doc = inspect.getdoc(isPalindrome)
    
    func_count = len(re.findall(r'isPalindrome', doc))
    true_count = len(re.findall(r'True', doc))
    false_count = len(re.findall(r'False', doc))
    pp_count = len(re.findall(r'>>>', doc))
    trace_count = len(re.findall(r'Traceback', doc))

    fptr.write(str(res)+'\n')
    fptr.write(str(func_count)+'\n')
    fptr.write(str(true_count)+'\n')
    fptr.write(str(false_count)+'\n')
    fptr.write(str(pp_count) + '\n')
    fptr.write(str(trace_count) + '\n')

    fptr.close()

Answer 2

Small Modification ---- Use below code

import math
import os
import random
import re
import sys
import inspect


def isPalindrome(x):
    """
    >>> isPalindrome(121)
    True
    >>> isPalindrome(344)
    False
    >>> isPalindrome(-121)
    Traceback (most recent call last):
    ValueError: x must be positive integer.
    >>> isPalindrome("hello")
    Traceback (most recent call last):
    TypeError: x must be integer.
    """  
    try:
        x = int(x)
        temp=x
        rev=0
        if(x>0):
            while(x>0):
                dig=x%10
                rev=rev*10+dig
                x=x//10
            if(temp==rev):
                return True
            else:
                return False
        elif(x<0):
            raise TypeError
        else:
            raise ValueError
    except ValueError:
        raise ValueError("x must be positive integer")
    except TypeError:
        raise TypeError("x must be an integer")

Answer 3

Use Value Error for x which is less then Zero. In your code, for Negative value of x, you called Type Error. You have to call Value Error.

    try:
        x = int(x)
        temp=x
        rev=0
        if(x>0):
            while(x>0):
                dig=x%10
                rev=rev*10+dig
                x=x//10
            if(temp==rev):
                return True
            else:
                return False
        elif(x<0):
            raise ValueError
        else:
            raise TypeError
    except ValueError:
        raise ValueError("x must be positive integer")
    except TypeError:
        raise TypeError("x must be an integer")

Answer 4

This is the function 'isPalindrome' to check if given number positive number is palindrome or not and return True and False correspondingly.

def isPalindrome(x):
    # Write the doctests:
    """
    >>>isPalindrome(121)
    True
    >>>isPalindrome(344)
    False
    >>>isPalindrome(-121)
    Traceback (most recent call last):
    ValueError: x must be positive integer
    >>>isPalindrome("hello")
    Traceback (most recent call last):
    TypeError: x must be integer
    """
    # Write the functionality:
    s = str(x)
    li = list(s)
    li.reverse()
    s1 = ''.join(li)
    if x == int(s1):
        return True
    else:
        return False

Answer 5

**

# Using the below code. You wont face any issues
def isPalindrome(x):
    # Write the doctests:
    """
    >>>isPalindrome(121)
    True
    >>>isPalindrome(344)
    False
    >>>isPalindrome(-121)
    Traceback (most recent call last):
    ValueError:X must be a positive integer
    >>>isPalindrome("hello")
    Traceback (most recent call last):
    ValueError:X must be an integer
    """
    # Write the functionality:

    return str(x)==str(x)[::-1]

**

Answer 6

Complete the isPalindrome function below.

def isPalindrome(x):
    # Write your doctests below.
    """
    >>> isPalindrome(121)
    True
    >>> isPalindrome(344)
    False
    >>> isPalindrome(-121)
    Traceback (most recent call last):
    ...
    ValueError: x must be a positive integer
    >>> isPalindrome("Hello")
    Traceback (most recent call last):
    ...
    ValueError: x must be an integer
    """  

    # Write the functionality below
    try:
        x = int(x)
        temp=x
        rev=0
        if(x>0):
            while(x>0):
                dig=x%10
                rev=rev*10+dig
                x=x//10
            if(temp==rev):
                return True
            else:
                return False
        elif(x<0):
            raise ValueError
        else:
            raise TypeError
    except ValueError:
        raise ValueError("x must be positive integer")
    except TypeError:
        raise TypeError("x must be an integer")

Answer 7

Use this:

def isPalindrome(x):
    # Write your doctests below.
    """
    >>> isPalindrome(121)
    True
    >>> isPalindrome(344)
    False
    >>> isPalindrome(-121)
    Traceback (most recent call last):
    ValueError: x must be positive integer.
    >>> isPalindrome("hello")
    Traceback (most recent call last):
    TypeError: x must be integer.
    """  

    # Write the functionality below
    try:
        x = int(x)
        temp=x
        rev=0
        if(x>0):
            while(x>0):
                dig=x%10
                rev=rev*10+dig
                x=x//10
            if(temp==rev):
                return True
            else:
                return False
        elif(x<0):
            raise TypeError
        else:
            raise ValueError
    except ValueError:
        raise ValueError("x must be positive integer")
    except TypeError:
        raise TypeError("x must be an integer")