QCoreApplication.postEvent(receiver, event) give good result only with input function-CodePudding

To perform unitary tests on the following part of a code (I use ... to replace unnecessary things to simplify)

from PyQt5.QtWidgets import QWidget, QLineEdit

// ...

class Controller(QWidget):
    def __init__(self, ...)
        // ...
        self.line_edit_name = QLineEdit()
        // ...
    def display_parameters(self, name, ...)
        self.line_edit_name.setText(name)
            self.line_edit_name.setReadOnly(False)
            self.line_edit_name.returnPressed.connect(
                partial(self.update_name, ...))
    def update_name(self, ...):
        // ...

I use this piece of code for tests using unittest:

from PyQt5 import QtCore, QtGui
from PyQt5.QtCore import QCoreApplication, QEvent
// ...
a = Controller()
a.line_edit_name.setText("Shakespeare")
keyEvent = QtGui.QKeyEvent(QtCore.QEvent.KeyPress, QtCore.Qt.Key_Return, QtCore.Qt.NoModifier)
QCoreApplication.postEvent(a.line_edit_name, keyEvent)
// ...

it worked very well during the debugging phase (I use input('foo') a lot to introspect and see step by step what is going on) ... But if I remove the input function it doesn't work anymore !!!!

In summary: the following script gives the right result

    a = Controller()
    a.line_edit_name.setText("Shakespeare")
    keyEvent = QtGui.QKeyEvent(QtCore.QEvent.KeyPress, QtCore.Qt.Key_Return, QtCore.Qt.NoModifier)
    QCoreApplication.postEvent(a.line_edit_name, keyEvent)
    input("foo")
    //...

the following not

    a = Controller()
    a.line_edit_name.setText("Shakespeare")
    keyEvent = QtGui.QKeyEvent(QtCore.QEvent.KeyPress, QtCore.Qt.Key_Return, QtCore.Qt.NoModifier)
    QCoreApplication.postEvent(a.line_edit_name, keyEvent)
    // ...

Because unit tests are done automatically during continuous integration we cannot use the input function. Why this result and how to do without input function?

Edit: By doing various tests I think that the input() function just allows processes to finish before the next command. I tried just after QCoreApplication.postEvent(a.line_edit_name, keyEvent), in place of input("foo"), threading.Event().wait(1) or time.sleep(1) without success ...

CodePudding user response：

In Qt, the task of sending the event and invoking the slots associated with signals is asynchronous, so do not expect to get a response instantly, but you must wait. In this case you must use QTest.qWait.

Since you do not provide an MRE then I will only show a simple demo:

from functools import partial

from PyQt5.QtCore import QCoreApplication, QEvent, Qt
from PyQt5.QtGui import QKeyEvent
from PyQt5.QtWidgets import QApplication, QFormLayout, QLineEdit, QWidget
from PyQt5.QtTest import QTest


class Controller(QWidget):
    def __init__(self, parent=None):
        super().__init__(parent)
        self.current_name = ""
        self.line_edit_name = QLineEdit()
        lay = QFormLayout(self)
        lay.addRow("name", self.line_edit_name)

    def display_parameters(self, name):
        self.line_edit_name.setText(name)
        self.line_edit_name.setReadOnly(False)
        self.line_edit_name.returnPressed.connect(partial(self.update_name, name))

    def update_name(self, name):
        self.current_name = name


def test_controller():
    app = QApplication([])

    a = Controller()
    a.display_parameters("Foo")

    assert a.current_name != "Foo"

    keyEvent = QKeyEvent(QEvent.KeyPress, Qt.Key_Return, Qt.NoModifier)
    QCoreApplication.postEvent(a.line_edit_name, keyEvent)
    # QTest.keyClick(a.line_edit_name, Qt.Key_Return)

    QTest.qWait(1000)

    assert a.current_name == "Foo"


test_controller()

On the other hand if you want to do tests then it is better to use the QtTest submodule that already has several simplified functions besides you could use pytest-qt.