测试MatSelectChange单元测试角度9 Karma

Question

我在角度9的单元测试中遇到问题，我不知道如何测试此功能，我无法对其进行测试。

import os
import sys

class SimplePool:
    """
    a simple pool that runs up to <n> processes in parallel, 
    but it doesn't communicate with them
    """
    def __init__(self, size):
        self.size = size

    def starmap(self, func, it):
        n_running = 0
        for values in it:
            while n_running == self.size:
                os.wait()
                n_running -= 1
            if os.fork() == 0:
                func(*values)
                sys.exit(0)
            n_running += 1
        while n_running > 0:
            os.wait()
            n_running -= 1

请帮助我！