PyQt QProgressBar not working when I use it with Selenuim

Question

I built a PyQt5 GUI to do some Selenium testing. Everything works as expected, except for the PyQt progress bar.

In the first example below, where I use the Selenium

Answer 1

The blocking tasks are not friendly with the event loop where the GUI is executed as they prevent the normal tasks that the GUI performs such as ticket checking, redrawing, etc. from being executed.

The solution in these cases is to use thread to execute the blocking task and use the signals to send the information.

import sys

from PyQt5 import QtCore, QtWidgets

from selenium import webdriver

class SeleniumWorker(QtCore.QObject):
    progressChanged = QtCore.pyqtSignal(int)
    def doWork(self):
        progress = 0
        browser = webdriver.Firefox()
        links = ['http://www.somesite.com/',
        'http://www.somesite.com/page2',
        'http://www.somesite.com/page3']
        for link in links:
            browser.get(link)
            progress += 100 / len(links)
            self.progressChanged.emit(progress)
        browser.close()

class Widget(QtWidgets.QWidget):
    def __init__(self, *args, **kwargs):
        QtWidgets.QWidget.__init__(self, *args, **kwargs)
        lay = QtWidgets.QHBoxLayout(self)
        progressBar = QtWidgets.QProgressBar()
        progressBar.setRange(0, 100)
        button = QtWidgets.QPushButton("Start")
        lay.addWidget(progressBar)
        lay.addWidget(button)
        self.thread = QtCore.QThread()
        self.worker = SeleniumWorker()
        self.worker.moveToThread(self.thread)
        self.thread.started.connect(self.worker.doWork)
        button.clicked.connect(self.thread.start)
        self.worker.progressChanged.connect(progressBar.setValue, QtCore.Qt.QueuedConnection)


if __name__ == '__main__':
    app = QtWidgets.QApplication(sys.argv)
    w = Widget()
    w.show()
    sys.exit(app.exec_())