unittest：wxpython的事件方法引发异常，但assertRaises没有检测到它

Question

我有一个 wxpython 对话框，单击“确定”按钮时会引发 TypeError 异常。我想用unittest测试异常的发生，但测试没有按预期工作。输出显示引发了异常。无论如何，unittest 通知测试失败：

"C:\Program Files (x86)\Python\python.exe" test.py
Traceback (most recent call last):
  File "test.py", line 22, in on_ok
    raise TypeError( 'TypeError raised' )
TypeError: TypeError raised
F
======================================================================
FAIL: test_should_raise (__main__.CDlgTest)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "test.py", line 34, in test_should_raise
    self._dut.m_button_ok.GetEventHandler().ProcessEvent( event )
AssertionError: TypeError not raised

----------------------------------------------------------------------
Ran 1 test in 0.005s

FAILED (failures=1)

这是我的代码的简化示例：

import unittest
import wx

class CDlgBase ( wx.Dialog ):
    """The UI"""
    def __init__( self, parent ):
        wx.Dialog.__init__ ( self, parent )
        bSizerTest = wx.BoxSizer( wx.VERTICAL )
        self.m_button_ok = wx.Button( self, wx.ID_ANY )
        bSizerTest.Add( self.m_button_ok, 0 )
        self.SetSizer( bSizerTest )
        # Connect Events
        self.m_button_ok.Bind( wx.EVT_BUTTON, self.on_ok )
    def on_ok( self, event ):
        event.Skip()

class CDlg( CDlgBase ) :
    """The dialog"""
    def __init__(self, parent):
        super( CDlg, self).__init__(parent)
    def on_ok(self, event):
        # The exception should be verified in the test `test_should_raise()`.
        raise TypeError( 'TypeError raised' )

class CDlgTest( unittest.TestCase ) :
    """The test class"""
    def setUp(self):
        self._dut = CDlg(None)
    def test_should_raise(self):
        """The test to verify raising the TypeError exception in the event 
        method `on_ok()`. this is the test method which works not as expected."""
        event = wx.CommandEvent( wx.EVT_BUTTON.evtType[0] )
        event.SetEventObject( self._dut.m_button_ok )
        with self.assertRaises( TypeError ) :
            """Simulate an "OK" click. `on_ok()` will be executed 
            and raises the TypeError exception."""
            self._dut.m_button_ok.GetEventHandler().ProcessEvent( event )

if __name__ == '__main__':
    app = wx.App()
    tests = [ unittest.TestLoader().loadTestsFromTestCase( CDlgTest) ]
    unittest.TextTestRunner(verbosity=2, failfast=True).run(unittest.TestSuite(tests) )

有人可以帮我找出我做错了什么吗？

Answer 1

参见：https://wiki.wxpython.org/CppAndPythonSandwich

异常不会通过 C++ 层向上传递到调用堆栈。 当控制从 Python 返回到 C++ 时，它会检查是否存在未捕获的 Python 异常，如果是，则打印并清除错误。

在单元测试中处理此问题的一种方法是在事件处理程序中捕获异常，并设置一个标志。 然后返回测试代码，您可以检查该标志是否已设置。