How to dynamically change label texts in pyqt5 by passing a text widget into a function?

I want to dynamically edit the content of a QLineEdit text, by passing the Widget to a function that initiates a filedialoge. The text of the passed widget shall then be set to the selected file.
Obviously I do not want to create a function for each QLineEdit Widget.

This is the current state (which is obviously not working).

import sys
from PyQt5.QtGui import *
from PyQt5.QtCore import *
from PyQt5.QtWidgets import *

class UserInterface(QWidget):

    def __init__(self, *args, **kwargs):
        super(UserInterface, self).__init__(*args, **kwargs)
        self.layout = QFormLayout()

        self.button_test_1 = QPushButton("Select File")
        self.line_test_1 = QLineEdit("Select File")
        self.button_test_1.clicked.connect(lambda: self.select_file(self.line_test_1))      
        self.layout.addRow(self.button_test_1,self.line_test_1)

        self.button_test_2 = QPushButton("Select File")
        self.line_test_2 = QLineEdit("Select File")
        self.button_test_2.clicked.connect(lambda: self.select_file(self.line_test_2))      
        self.layout.addRow(self.button_test_2,self.line_test_2)

        self.setLayout(self.layout)

    def select_file(self,line):
        fileName = QFileDialog.getOpenFileName(self,"Choose File",directory="D:\\",filter="*.json *.csv")
        self.line.setText(fileName)

def main():
    app  = QApplication(sys.argv)

    controller = UserInterface()
    controller.show()

    sys.exit(app.exec_())

main()

Currently it results in an error als "self.line" does not exist.

In the end I want to be able to pass self.line_test_[n](or any other name) to my select_file function and set the text of the passed Wigdet within the function.

You just need to remove self keyword for it to work:

    def select_file(self, line):
        fileName = QFileDialog.getOpenFileName(self, ,"Choose File",directory="D:\\",filter="*.json *.csv")[0] # Make sure to use [0] here to get the file name.
        line.setText(fileName) # Remove self here

However, the setText will break right away since the value of fileName is not string but a tuple. Therefore you need to put [0] after ..."*.json *.csv")