Unittest setUpClass run multiple times

[ClementPhan]

Environment data

• VS Code version: 1.60
• Extension version: v2021.9.1191016588
• OS and version: Windows 20H2
• Python version: 3.9.2
• Type of virtual environment used: none
• Relevant/affected Python packages and their versions: Unittest
• Value of the python.languageServer setting: Pylance

Expected behaviour

When running discovered tests with Unittest as a class, the execution of a whole test class should call method setUpClass once.

The behaviour should follow the design of setUp and setUpClass with the former being run once for each test, the latter once for each class.

Actual behaviour

When running all tests, tests are run one by one. This leads to an execution of setUpClass for each test, negating possible efficiency gains.

The behaviour changed from expected to actual between beginning of August and September 3rd.

Steps to reproduce:

1. Add test file to test explorer
2. Run all tests

Minimal Working Example

import unittest
import time

class set_up_Test(unittest.TestCase):
    @classmethod
    def setUpClass(cls):
        #long task
        time.sleep(5)
        
    def test_1(self):
        self.assertEqual(1,1)
        
    def test_2(self):
        self.assertEqual(2,2)
        
    def test_3(self):
        self.assertEqual(3,3)
        
    def test_4(self):
        self.assertEqual(4,4)