Pyqt5: builtins.AttributeError: 'QDialog' object has no attribute 'setCentralWidget' - python-3.x

Question

I converted ui file from Pyqt5 designer:
Testing1.py
from PyQt5 import QtCore, QtGui, QtWidgets
class Ui_MainWindow(object):
def setupUi(self, MainWindow):
MainWindow.setObjectName("MainWindow")
MainWindow.resize(800, 600)
self.centralwidget = QtWidgets.QWidget(MainWindow)
self.centralwidget.setObjectName("centralwidget")
self.pushButton = QtWidgets.QPushButton(self.centralwidget)
self.pushButton.setGeometry(QtCore.QRect(380, 180, 112, 34))
self.pushButton.setObjectName("pushButton")
MainWindow.setCentralWidget(self.centralwidget)
self.menubar = QtWidgets.QMenuBar(MainWindow)
self.menubar.setGeometry(QtCore.QRect(0, 0, 800, 31))
self.menubar.setObjectName("menubar")
MainWindow.setMenuBar(self.menubar)
self.statusbar = QtWidgets.QStatusBar(MainWindow)
self.statusbar.setObjectName("statusbar")
MainWindow.setStatusBar(self.statusbar)
self.retranslateUi(MainWindow)
QtCore.QMetaObject.connectSlotsByName(MainWindow)
def retranslateUi(self, MainWindow):
_translate = QtCore.QCoreApplication.translate
MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow"))
self.pushButton.setText(_translate("MainWindow", "PushButton"))
if __name__ == "__main__":
import sys
app = QtWidgets.QApplication(sys.argv)
MainWindow = QtWidgets.QMainWindow()
ui = Ui_MainWindow()
ui.setupUi(MainWindow)
MainWindow.show()
sys.exit(app.exec_())
Test1.py < is meant to add methods etc. etc.
import sys
from PyQt5 import QtWidgets, QtCore, QtGui
from testing1 import Ui_MainWindow
class myprog(Ui_MainWindow):
def __init__ (self, dialog):
Ui_MainWindow.__init__(self)
self.setupUi(dialog)
if __name__ == '__main__':
app = QtWidgets.QApplication(sys.argv)
dialog = QtWidgets.QDialog()
test1 = myprog(dialog)
dialog.show()
sys.exit(app.exec_())
If I run Testin1.py it's all ok, but if run second script, test1.py, i get following message:
> builtins.AttributeError: 'QDialog' object has no attribute
> 'setCentralWidget'
I am really confused what to do, I would really really appreciate, if you could help me solve this problem. Any help is more than welcome.

Answer 1

In Testing1.py file, you create a MainWindow.
So in your Test1.py file, you should change the code
dialog = QtWidgets.QDialog()
to
dialog = QtWidgets.QMainWindow()