Why won't QGIS let me write to a file?

Question

I am writing a QGIS Python Plugin. I am trying to write data to a file using

with open("filename.txt", "w") as f: 
    f.write("file text.")
QMessageBox.information(None, "Test", "Written to file.")

It runs the above and displays the message but it does not write to the file. Why is it not writing to the file? No exceptions are raised.

Thank-you in advance.

Answer 1

Python is doing what you tell it and that is to create a file in the current working directory which when you are running QGIS is your QGIS install location. Try running this in the Python console:

f = open("test.txt",'w')
os.path.abspath(f.name)

What you should really do is tell open the path to where you want to store the file:

import os
p = os.path.join(os.path.dirname(__file__), 'test.txt')
f = open(p,'w')
os.path.abspath(f.name)