how to check if textedit empty?

It is a function to tts after overwriting the textedit value to the txt file. However, if textedit is executed in a blank state, a 'No text to speak' error message is displayed and it is terminated. I tried to open messagebox use 'if-statement' if textedit is empty. but doesn't work. I'll appreciate for your help.

def btstart(self):
    text = self.textEdit.toPlainText()
    with open('log.txt', 'w') as file:
        file.write(text)
    if str(text != ""):
        file = open("log.txt", "r").read().replace("\n", " ")
        tts = gTTS(text = str(file),lang='ko',slow = False)
        tts.save("voice.mp3")
        pygame.init()
        pygame.mixer.music.load('./voice.mp3')
        pygame.mixer.music.play()
        clock = pygame.time.Clock()
        while pygame.mixer.music.get_busy():
            clock.tick(60)
            pygame.event.poll()

        os.remove("./voice.mp3")
        if not self.thread.isRunning():
            self.bt_start.setEnabled(False)
            self.thread.start()
    elif str(text == ""): 
        self.msg.setIcon(QMessageBox.Information)
        self.msg.setWindowTitle('empty text')
        self.msg.setText('input text')
        self.msg.setStandardButtons(QMessageBox.close)
        self.msg.exec_()