Add calculator with unit tests

calculator.py

@@ -0,0 +1,14 @@
+class Calculator:
+    def add(self, a, b):
+        return a + b
+
+    def subtract(self, a, b):
+        return a - b
+
+    def multiply(self, a, b):
+        return a * b
+
+    def divide(self, a, b):
+        if b == 0:
+            raise ValueError("Division by zero is not allowed")
+        return a / b

test_calculator.py

@@ -0,0 +1,27 @@
+import unittest
+from calculator import Calculator
+
+class TestCalculator(unittest.TestCase):
+    def setUp(self):
+        self.calc = Calculator()
+
+    def test_add(self):
+        self.assertEqual(self.calc.add(2, 3), 5)
+        self.assertEqual(self.calc.add(-1, 1), 0)
+
+    def test_subtract(self):
+        self.assertEqual(self.calc.subtract(5, 3), 2)
+        self.assertEqual(self.calc.subtract(0, 0), 0)
+
+    def test_multiply(self):
+        self.assertEqual(self.calc.multiply(2, 3), 6)
+        self.assertEqual(self.calc.multiply(-1, 5), -5)
+
+    def test_divide(self):
+        self.assertEqual(self.calc.divide(6, 3), 2)
+        self.assertEqual(self.calc.divide(5, 2), 2.5)
+        with self.assertRaises(ValueError):
+            self.calc.divide(1, 0)
+
+if __name__ == '__main__':
+    unittest.main()