Add a TraitsUITestAssistant class

traitsui/qt4/testing/traitsui_test_assistant.py

@@ -0,0 +1,142 @@
+#  Copyright (c) 2019, Enthought, Inc.
+#  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!
+
+from contextlib import contextmanager
+
+from pyface.ui.qt4.util.gui_test_assistant import GuiTestAssistant
+from traits.trait_base import xgetattr
+
+
+class TraitsUITestAssistant(GuiTestAssistant):
+    """ A Test Assistant for testing TraitsUI views.
+
+    For most efficient usage, this class expects the setUp to provide an
+    'object' attribute containing the main object being viewed.
+
+    Note
+    ----
+
+    This API is experimental and may change before the next feature release.
+    """
+
+    @contextmanager
+    def create_ui(self, object=None, **kwargs):
+        """ Create and dispose of a TraitsUI UI
+
+        This is a context manager which calls edit_traits on an object in
+        when entered and calls dispose when exiting, running the event
+        loop until the underlying toolkit object is destroyed.
+
+        Parameters
+        ----------
+        object : HasTraits instance or None
+            The object to call edit_traits on.  If None, then the method
+            will attempt to use self.object, if it exists.
+        **kwargs : keyword arguments
+            Additional keyword arguments will be passed through to
+            edit_traits.
+
+        Returns
+        -------
+        ui : UI instance
+            The context manager returns the UI instance created by
+            edit_traits.
+        """
+        if object is None:
+            object = self.object
+        ui = object.edit_traits(**kwargs)
+        try:
+            yield ui
+        finally:
+            with self.delete_widget(ui.control):
+                ui.dispose()
+
+    def set_editor_later(self, info, editor_id, value, trait_name='value'):
+        """ Set the a trait on an editor during ethe event loop.
+
+        Parameters
+        ----------
+        info : UIInfo instance
+            The UIInfo instance for the UI.
+        editor_id : str
+            The ID of the editor in the UI (defaults to the trait name of the
+            item).
+        value : any
+            The value to set on the editor.
+        trait_name : str
+            The trait to set on the editor.
+        """
+        if '.' in editor_id:
+            __, editor_id = editor_id.rsplit('.', 1)
+        editor = getattr(info, editor_id)
+        self.gui.set_trait_later(editor, trait_name, value)
+
+    def invoke_editor_later(self, info, editor_id, method='update_object',
+                            *args, **kwargs):
+        """ Call a method on an editor during ethe event loop.
+
+        Parameters
+        ----------
+        info : UIInfo instance
+            The UIInfo instance for the UI.
+        editor_id : str
+            The ID of the editor in the UI (defaults to the trait name of the
+            item).
+        method : str
+            The name of the method on the editor.
+        *args, **kwargs
+            Additional positional and keyword arguments to pass to the method.
+        """
+        if '.' in editor_id:
+            __, editor_id = editor_id.rsplit('.', 1)
+        editor = getattr(info, editor_id)
+        method = getattr(editor, method)
+        self.gui.invoke_later(method, *args, **kwargs)
+
+    def assertItemChanges(self, name, value, object=None, **ui_args):
+        """ Test that setting a value on an editor changes the underlying trait.
+
+        Parameters
+        ----------
+        name : str
+            The identifier of the Item being changed.
+        value : str
+            The value being changed.
+        object : HasTraits instance
+            The object to call edit_traits on.  If None, then the method
+            will attempt to use self.object, if it exists.
+        **uiargs
+            Additional keyword arguments to pass to the edit_traits method.
+        """
+        if object is None:
+            object = self.object
+        with self.create_ui(object, **ui_args) as ui:
+            target, extended_trait = self._process_item_name(ui, name)
+            with self.event_loop_until_traits_change(target, extended_trait):
+                self.set_editor_later(ui.info, extended_trait, value)
+
+        self.assertEqual(xgetattr(target, extended_trait), value)
+
+    # ------------------------------------------------------------------------
+    # Private API
+    # ------------------------------------------------------------------------
+
+    def _process_item_name(self, ui, name):
+        """ Extract the target object and extended trait name from the item id
+        """
+        # XXX this almost certainly exists elsewhere,
+        # XXX or _should_ exist elsewhere
+        if '.' in name:
+            target, extended_trait = name.split('.', 1)
+            target = ui.context[target]
+        else:
+            extended_trait = name
+            target = ui.context['object']
+        return target, extended_trait