How to print test output to a label in pyqt gui

Question

what I am trying to do with a python script: Use a pytest test method to print a text line to a label in the pyqt GUI.

When running the main python file, the GUI starts and a click on the "test" button runs the test without blocking the GUI (see full code example below). But I have no clue how to proceed now.

Code:

import sys

import pytest
from PyQt5 import QtWidgets, QtCore
from PyQt5.QtWidgets import QApplication, QVBoxLayout, QWidget


class Window(QtWidgets.QMainWindow):
    signal_start_background_job = QtCore.pyqtSignal()

    def __init__(self):
        super(Window, self).__init__()

        layout = QVBoxLayout()
        self.button = QtWidgets.QPushButton("test", self)
        self.label = QtWidgets.QLabel("console output")
        layout.addWidget(self.button)
        layout.addWidget(self.label)
        widget = QWidget()
        widget.setLayout(layout)
        self.setCentralWidget(widget)

        self.worker = WorkerObject()
        self.thread = QtCore.QThread()
        self.worker.moveToThread(self.thread)

        self.signal_start_background_job.connect(self.worker.background_job)
        self.button.clicked.connect(self.start_background_job)

    def start_background_job(self):
        self.thread.start()
        self.signal_start_background_job.emit()


class WorkerObject(QtCore.QObject):
    @QtCore.pyqtSlot()
    def background_job(self):
        pytest.main(["-s", "-k test_something"])


if __name__ == "__main__":
    app = QApplication(sys.argv)
    window = Window()
    window.show()
    sys.exit(app.exec_())


def test_something():
    print("unit test some stuff")
    assert 0 == 0

score 1 · Accepted Answer · answered Mar 16 '20 at 17:52

Instead of using pytest directly you could use QProcess to launch it and then capture the output:

import os
import sys

from PyQt5 import QtWidgets, QtCore
from PyQt5.QtWidgets import QApplication, QVBoxLayout, QWidget

CURRENT_DIR = os.path.dirname(os.path.realpath(__file__))


class Window(QtWidgets.QMainWindow):
    def __init__(self):
        super(Window, self).__init__()

        self.button = QtWidgets.QPushButton("test", self)
        self.label = QtWidgets.QLabel("console output")
        self.textedit = QtWidgets.QTextEdit(readOnly=True)

        widget = QWidget()
        layout = QVBoxLayout(widget)
        layout.addWidget(self.button)
        layout.addWidget(self.label)
        layout.addWidget(self.textedit)
        self.setCentralWidget(widget)

        self.process = QtCore.QProcess()
        self.process.setProgram(sys.executable)
        self.process.readyReadStandardError.connect(self.on_readyReadStandardError)
        self.process.readyReadStandardOutput.connect(self.on_readyReadStandardOutput)

        self.button.clicked.connect(self.on_clicked)

    @QtCore.pyqtSlot()
    def on_clicked(self):
        self.process.setWorkingDirectory(CURRENT_DIR)
        self.process.setArguments(["-m", "pytest", "-s", "-k", "test_something"])
        self.process.start()

    @QtCore.pyqtSlot()
    def on_readyReadStandardError(self):
        err = self.process.readAllStandardError().data().decode()
        self.textedit.append(err)

    @QtCore.pyqtSlot()
    def on_readyReadStandardOutput(self):
        out = self.process.readAllStandardOutput().data().decode()
        self.textedit.append(out)


if __name__ == "__main__":
    app = QApplication(sys.argv)
    window = Window()
    window.show()
    sys.exit(app.exec_())

Thank you for the fast answer :) – TylMH Mar 17 '20 at 15:47 — TylMH, Mar 17 '20 at 15:47

score 0 · Answer 2 · answered Mar 16 '20 at 17:25

I'm thinking you need to check out sys.stdout, and route that to an io object that you can route to the label in your widget. Then I would set a timer and every 0.1 seconds or so set the text of your label to that object. Alternatively you can implement a widget that grabs the stdout text in qt, example here: https://stackoverflow.com/a/1220002/6615517 I haven't tried it but the other answers to that question should help. You'll probably want to clear the label on each test to prevent it from getting too long.

How to print test output to a label in pyqt gui

2 Answers2