old_contents: from Calculator import operations
  from unittest import TestCase
  
  
  class TestOperations(TestCase):
  
      def test_addition(self):
          assert operations.add(1,2) == 3
  
  
new_contents: from Calculator import operations
  from unittest import TestCase
  
  
  class TestOperations(TestCase):
  
      def test_addition(self):
          assert operations.add(1,2) == 3
  
      def test_subtraction(self):
          assert operations.subtract(1,2) == -1
  
      def test_multiplication(self):
          assert operations.multiply(2,-1) == -2
  
      def test_divide(self):
          #test for floating point division returns floating point
          assert type(operations.divide(3,2)) == float
          assert operations.divide(8,4) == 2
          #Check for div by zero
          assert operations.divide(1,0) == None
      
  
subject: add more tests