Add wx toolkit support

.travis.yml

@@ -7,6 +7,7 @@ services:
 addons:
   apt:
     packages:
+    # Qt dependencies
     - qt5-default
     - libxkbcommon-x11-0
     - libxcb-icccm4
@@ -15,6 +16,8 @@ addons:
     - libxcb-randr0
     - libxcb-render-util0
     - libxcb-xinerama0
+    # wxPython dependencies
+    - libsdl2-2.0-0
 
 env:
   global:
@@ -35,6 +38,8 @@ matrix:
     env: CI_PYTHON_VERSION="py36" CI_TOOLKIT="pyqt5"
   - os: linux
     env: CI_PYTHON_VERSION="py36" CI_TOOLKIT="pyside2"
+  - os: linux
+    env: CI_PYTHON_VERSION="py36" CI_TOOLKIT="wxpython"
   - os: osx
     env: CI_PYTHON_VERSION="py36" CI_TOOLKIT="null"
   - os: osx
@@ -43,6 +48,8 @@ matrix:
     env: CI_PYTHON_VERSION="py36" CI_TOOLKIT="pyqt5"
   - os: osx
     env: CI_PYTHON_VERSION="py36" CI_TOOLKIT="pyside2"
+  - os: osx
+    env: CI_PYTHON_VERSION="py36" CI_TOOLKIT="wxpython"
 
 before_install:
   - mkdir -p "${HOME}/.cache/download"

appveyor.yml

@@ -15,6 +15,8 @@ environment:
       CI_TOOLKIT: "pyqt5"
     - CI_PYTHON_VERSION: "py36"
       CI_TOOLKIT: "pyside2"
+    - CI_PYTHON_VERSION: "py36"
+      CI_TOOLKIT: "wxpython"
 
 cache:
   - C:\Users\appveyor\.cache -> appveyor-clean-cache.txt

ci/__main__.py

@@ -107,6 +107,25 @@ def build(edm, python_version, toolkit, mode):
     pyenv.create()
     pyenv.install(dependencies)
 
+    # wxPython installation needs special handling, especially on Linux
+    # Ref: https://wxpython.org/pages/downloads/
+    if toolkit == cfg.WXPYTHON:
+        wxpython_install_options = []
+        if current_platform() == cfg.LINUX:
+            wxpython_install_options += [
+                "-f",
+                "https://extras.wxpython.org/wxPython4/extras/linux/gtk3/ubuntu-16.04",  # noqa: E501
+            ]
+
+        wxpython_install_cmd = [
+            "-m",
+            "pip",
+            "install",
+            *wxpython_install_options,
+            "wxPython",
+        ]
+        pyenv.python(wxpython_install_cmd)
+
     # Install local packages.
     local_packages = ["./"]
     pip_options = ["--editable"] if mode == "develop" else []

ci/config.py

@@ -33,7 +33,8 @@
 PYQT = "pyqt"  # Qt 4, PyQt
 PYQT5 = "pyqt5"  # Qt 5, PyQt
 PYSIDE2 = "pyside2"  # Qt 5, Qt for Python
-TOOLKITS = [NULL, PYQT, PYQT5, PYSIDE2]
+WXPYTHON = "wxpython"  # wxPython 4
+TOOLKITS = [NULL, PYQT, PYQT5, PYSIDE2, WXPYTHON]
 
 # Default Python version and toolkit.
 DEFAULT_PYTHON = PYTHON36
@@ -96,6 +97,9 @@
     (MACOS, PYTHON36, PYSIDE2),
     (LINUX, PYTHON36, PYSIDE2),
     (WINDOWS, PYTHON36, PYSIDE2),
+    (MACOS, PYTHON36, WXPYTHON),
+    (LINUX, PYTHON36, WXPYTHON),
+    (WINDOWS, PYTHON36, WXPYTHON),
 ]
 
 # Dependencies needed for all platforms, toolkits and Python versions.
@@ -123,6 +127,9 @@
     PYQT: ["pyqt", "traitsui"],
     PYQT5: ["pyqt5", "traitsui"],
     PYSIDE2: ["pyside2", "traitsui"],
+    # wxPython is not yet available through EDM, and needs special
+    # handling in the main script.
+    WXPYTHON: ["traitsui"],
 }
 
 # Additional packages needed for local development, examples.

setup.py

@@ -68,6 +68,7 @@ def get_long_description():
             "null = traits_futures.null.init:toolkit_object",
             "qt4 = traits_futures.qt.init:toolkit_object",
             "qt = traits_futures.qt.init:toolkit_object",
+            "wx = traits_futures.wx.init:toolkit_object",
         ],
     },
     python_requires=">=3.6",

traits_futures/tests/test_gui_test_assistant.py

@@ -45,42 +45,58 @@ def tearDown(self):
     def test_run_until_timeout(self):
         # Trait never fired, condition never true.
         dummy = Dummy()
+
+        start_time = time.monotonic()
         with self.assertRaises(RuntimeError):
             self.run_until(
                 dummy,
                 "never_fired",
                 condition=lambda object: False,
                 timeout=0.1,
             )
+        actual_timeout = time.monotonic() - start_time
+        # We're being ultra-conservative here; on a typical system, the actual
+        # time taken to fail shouldn't be much more than the 0.1 timeout. But
+        # at least this test catches the bug of using the default timeout of 10
+        # seconds.
+        self.assertLess(actual_timeout, 1.0)
 
     def test_run_until_timeout_trait_fired(self):
         # Trait fired, but condition still never true.
         executor = TraitsExecutor()
         future = submit_call(executor, int, "111")
+        start_time = time.monotonic()
         with self.assertRaises(RuntimeError):
             self.run_until(
                 future,
                 "state",
                 condition=lambda future: future.state == CANCELLED,
                 timeout=0.1,
             )
+        actual_timeout = time.monotonic() - start_time
 
         executor.stop()
         self.run_until(
             executor,
             "stopped",
             condition=lambda executor: executor.stopped,
         )
+        self.assertLess(actual_timeout, 1.0)
 
     def test_run_until_timeout_with_true_condition(self):
         # Trait never fired, but condition true anyway.
         dummy = Dummy()
+        start_time = time.monotonic()
         self.run_until(
             dummy,
             "never_fired",
             condition=lambda object: True,
             timeout=10.0,
         )
+        actual_timeout = time.monotonic() - start_time
+        # The actual time take for the run_until call to return should
+        # be close to zero.
+        self.assertLess(actual_timeout, 1.0)
 
     def test_run_until_success(self):
         # Trait fired, condition starts false but becomes true.

traits_futures/wx/gui_test_assistant.py

@@ -0,0 +1,176 @@
+# (C) Copyright 2018-2020 Enthought, Inc., Austin, TX
+# All rights reserved.
+#
+# This software is provided without warranty under the terms of the BSD
+# license included in LICENSE.txt and may be redistributed only under
+# the conditions described in the aforementioned license. The license
+# is also available online at http://www.enthought.com/licenses/BSD.txt
+#
+# Thanks for using Enthought open source!
+
+"""
+Test support, providing the ability to run the event loop from tests.
+"""
+
+import wx
+
+
+#: Default timeout, in seconds
+TIMEOUT = 10.0
+
+# XXX We should be using Pyface's own CallbackTimer instead of creating
+# our own, but we were running into segfaults.
+# xref: enthought/pyface#815, enthought/traits-futures#251
+
+
+class TimeoutTimer(wx.Timer):
+    """
+    Single-shot timer that executes a given callback on completion.
+
+    Parameters
+    ----------
+    timeout : float
+        Timeout in seconds.
+    callback : callable
+        Callable taking no arguments, to be executed when the timer
+        times out.
+    args : tuple, optional
+        Tuple of positional arguments to pass to the callable. If not
+        provided, no positional arguments are passed.
+    kwargs : dict, optional
+        Dictionary of keyword arguments to pass to the callable. If not
+        provided, no keyword arguments are passed.
+    """
+
+    def __init__(self, timeout, callback, args=(), kwargs=None):
+        wx.Timer.__init__(self)
+        self.timeout = timeout
+        self.callback = callback
+        self.args = args
+        self.kwargs = {} if kwargs is None else kwargs
+
+    def start(self):
+        """
+        Start the timer.
+        """
+        timeout_in_ms = round(self.timeout * 1000)
+        self.StartOnce(milliseconds=timeout_in_ms)
+
+    def stop(self):
+        """
+        Stop the timer if it hasn't already expired. The callback
+        will not be executed.
+        """
+        self.Stop()
+
+    def Notify(self):
+        """
+        Execute the callback when the timer completes.
+        """
+        self.callback(*self.args, **self.kwargs)
+
+
+class AppForTesting(wx.App):
+    """
+    Subclass of wx.App used for testing.
+    """
+
+    def OnInit(self):
+        """
+        Override base class to ensure we have at least one window.
+        """
+        # It's necessary to have at least one window to prevent the application
+        # exiting immediately.
+        self.frame = wx.Frame(None)
+        self.SetTopWindow(self.frame)
+        self.frame.Show(False)
+        return True
+
+    def exit(self, exit_code):
+        """
+        Exit the application main event loop with a given exit code.
+
+        The event loop can be started and stopped several times for
+        a single AppForTesting object.
+        """
+        self.exit_code = exit_code
+        self.ExitMainLoop()
+
+    def close(self):
+        """
+        Clean up when the object is no longer needed.
+        """
+        self.frame.Close()
+        del self.frame
+
+
+class GuiTestAssistant:
+    """
+    Support for running the wx event loop in unit tests.
+    """
+
+    def setUp(self):
+        self.wx_app = AppForTesting()
+
+    def tearDown(self):
+        self.wx_app.close()
+        del self.wx_app
+
+    def run_until(self, object, trait, condition, timeout=TIMEOUT):
+        """
+        Run event loop until the given condition holds true, or until timeout.
+
+        The condition is re-evaluated, with the object as argument, every time
+        the trait changes.
+
+        Parameters
+        ----------
+        object : traits.has_traits.HasTraits
+            Object whose trait we monitor.
+        trait : str
+            Name of the trait to monitor for changes.
+        condition : callable
+            Single-argument callable, returning a boolean. This will be
+            called with *object* as the only input.
+        timeout : float, optional
+            Number of seconds to allow before timing out with an exception.
+            The (somewhat arbitrary) default is 10 seconds.
+
+        Raises
+        ------
+        RuntimeError
+            If timeout is reached, regardless of whether the condition is
+            true or not at that point.
+        """
+
+        wx_app = self.wx_app
+
+        timeout_timer = TimeoutTimer(timeout, lambda: wx_app.exit(1))
+
+        def stop_if_condition():
+            if condition(object):
+                wx_app.exit(0)
+
+        object.on_trait_change(stop_if_condition, trait)
+        try:
+            # The condition may have become True before we
+            # started listening to changes. So start with a check.
+            if condition(object):
+                timed_out = 0
+            else:
+                timeout_timer.start()
+                try:
+                    wx_app.MainLoop()
+                finally:
+                    timed_out = wx_app.exit_code
+                    timeout_timer.stop()
+        finally:
+            object.on_trait_change(stop_if_condition, trait, remove=True)
+
+        if timed_out:
+            raise RuntimeError(
+                "run_until timed out after {} seconds. "
+                "At timeout, condition was {}.".format(
+                    timeout, condition(object)
+                )
+            )

traits_futures/wx/init.py

@@ -0,0 +1,20 @@
+# (C) Copyright 2018-2020 Enthought, Inc., Austin, TX
+# All rights reserved.
+#
+# This software is provided without warranty under the terms of the BSD
+# license included in LICENSE.txt and may be redistributed only under
+# the conditions described in the aforementioned license. The license
+# is also available online at http://www.enthought.com/licenses/BSD.txt
+#
+# Thanks for using Enthought open source!
+
+"""
+Entry point for finding toolkit-specific classes.
+"""
+# Force an ImportError if wxPython is not installed.
+import wx  # noqa: F401
+
+from pyface.base_toolkit import Toolkit
+
+#: The toolkit object used to find toolkit-specific resources
+toolkit_object = Toolkit("traits_futures", "wx", "traits_futures.wx")