From 1b5b668d8d43e234377b18614fa6cb15a1089a7f Mon Sep 17 00:00:00 2001
From: "google-labs-jules[bot]"
 <161369871+google-labs-jules[bot]@users.noreply.github.com>
Date: Sat, 13 Jun 2026 12:38:49 +0000
Subject: [PATCH] Refactor Calculator.py to conditionally evaluate arithmetic
 operations

Calculations for addition, subtraction, multiplication, and division
were previously evaluated eagerly before checking the user's selected
operation. This could lead to a crash due to `ZeroDivisionError` when
the user inputted `0` for `num2` even if division wasn't selected.

Moved calculation logic to the respective branches. Also added a
division by zero check, protected input from EOFError, and added
subprocess unit tests.

Co-authored-by: ManupaKDU <95234271+ManupaKDU@users.noreply.github.com>
---
 Part-1/wHATTA/Basics/Calculator.py      | 21 ++++++++----
 Part-1/wHATTA/Basics/test_calculator.py | 45 +++++++++++++++++++++++++
 2 files changed, 59 insertions(+), 7 deletions(-)
 create mode 100644 Part-1/wHATTA/Basics/test_calculator.py

diff --git a/Part-1/wHATTA/Basics/Calculator.py b/Part-1/wHATTA/Basics/Calculator.py
index d0ba607..a3bb8c5 100644
--- a/Part-1/wHATTA/Basics/Calculator.py
+++ b/Part-1/wHATTA/Basics/Calculator.py
@@ -1,17 +1,24 @@
 num1 = input("Enter you first number: ")
 num2 = input("Enter you second number: ")
 choice = input("Do you want to add(a) / substract(s) / mmultiply(m) / divide(d) ? ")
-add = int(num1)+int(num2)
-subs = int(num1)-int(num2)
-mult = int(num1)*int(num2)
-div = int(num1)/int(num2)
 if choice == 'a' :
+    add = int(num1)+int(num2)
     print("The addition is " + str(add))
 elif choice == 's' :
+    subs = int(num1)-int(num2)
     print("The substraction is " + str(subs))
 elif choice == 'm' :
+    mult = int(num1)*int(num2)
     print("The multipication is " + str(mult))
 elif choice == 'd' :
-    print("The division is " + str(div))
-input(""".............Thank you............. 
-Please press the ENTER button""")
\ No newline at end of file
+    if int(num2) == 0:
+        print("Cannot divide by zero")
+    else:
+        div = int(num1)/int(num2)
+        print("The division is " + str(div))
+
+try:
+    input(""".............Thank you.............
+Please press the ENTER button""")
+except EOFError:
+    pass
\ No newline at end of file
diff --git a/Part-1/wHATTA/Basics/test_calculator.py b/Part-1/wHATTA/Basics/test_calculator.py
new file mode 100644
index 0000000..9576428
--- /dev/null
+++ b/Part-1/wHATTA/Basics/test_calculator.py
@@ -0,0 +1,45 @@
+import unittest
+import subprocess
+import os
+
+class TestCalculator(unittest.TestCase):
+    def run_calculator(self, input_text):
+        script_path = os.path.join(os.path.dirname(__file__), 'Calculator.py')
+        process = subprocess.Popen(['python3', script_path], stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE, text=True)
+        stdout, stderr = process.communicate(input=input_text)
+        return stdout, stderr, process.returncode
+
+    def test_addition(self):
+        stdout, stderr, returncode = self.run_calculator("10\n5\na\n")
+        self.assertEqual(returncode, 0)
+        self.assertIn("The addition is 15", stdout)
+
+    def test_addition_zero_division_avoided(self):
+        # Even if num2 is 0, addition should work and not crash
+        stdout, stderr, returncode = self.run_calculator("10\n0\na\n")
+        self.assertEqual(returncode, 0)
+        self.assertIn("The addition is 10", stdout)
+        self.assertEqual(stderr, "")
+
+    def test_subtraction(self):
+        stdout, stderr, returncode = self.run_calculator("10\n5\ns\n")
+        self.assertEqual(returncode, 0)
+        self.assertIn("The substraction is 5", stdout)
+
+    def test_multiplication(self):
+        stdout, stderr, returncode = self.run_calculator("10\n5\nm\n")
+        self.assertEqual(returncode, 0)
+        self.assertIn("The multipication is 50", stdout)
+
+    def test_division(self):
+        stdout, stderr, returncode = self.run_calculator("10\n5\nd\n")
+        self.assertEqual(returncode, 0)
+        self.assertIn("The division is 2.0", stdout)
+
+    def test_division_by_zero(self):
+        stdout, stderr, returncode = self.run_calculator("10\n0\nd\n")
+        self.assertEqual(returncode, 0)
+        self.assertIn("Cannot divide by zero", stdout)
+
+if __name__ == '__main__':
+    unittest.main()