Unittesting PyQt app

I am trying to test my PyQt app. I need to view results of my unittest in PyQt widget but when I run unittesting the app closes.

This is my code: validation_test_app.py:

from PyQt5 import QtCore, QtWidgets
from PyQt5.QtNetwork import QNetworkAccessManager, QNetworkRequest
import sys
import unittest

def get_size(url):
    manager = QNetworkAccessManager()
    response = manager.get(QNetworkRequest(QtCore.QUrl(r"https://" + url)))
    event = QtCore.QEventLoop()
    response.finished.connect(event.quit)
    event.exec()
    html = response.readAll()
    size = html.size()
    return size

class MainWindow(QtWidgets.QWidget):
    def __init__(self, parent = None):
        super(MainWindow, self).__init__()

        self.layout = QtWidgets.QVBoxLayout()
        self.label = QtWidgets.QLabel("Checking tests...")

        self.btn = QtWidgets.QPushButton("push")
        self.btn.clicked.connect(self.btn_clicked)

        self.layout.addWidget(self.label, alignment=QtCore.Qt.AlignCenter)
        self.layout.addWidget(self.btn)
        self.setLayout(self.layout)

    def btn_clicked(self):
        unittest.main(module="validation_test")

if __name__ == "__main__":
    app = QtWidgets.QApplication(sys.argv)

    main_window = MainWindow()
    main_window.show()

    sys.exit(app.exec_())

validation_test.py:

import unittest
from validation_test_app import get_size

class TestUrls(unittest.TestCase):

    def test_1(self):
        size = get_size("apps4all.ru")
        self.assertEqual(size, 0)

    def test_2(self):
        size = get_size("google.com")
        self.assertNotEqual(size, 0)

I want to view results of testing in QLabel, for example. Is it real to implement ?