Add Tests for `Preferences>Keybidings`

This commit adds tests that check that:
1) Default key binding accelerators are distinct.
2) Message dialog appears when a duplicate key binding accelerator is
attempted to be assigned to a different action.
3) Duplicate key binding accelerator cannot refer to more than one action.

Also, `active_message_dialog` attribute was added to `PrefsEditor`, so
that tests could get a reference to a message dialog window.

terminatorlib/prefseditor.py

@@ -186,6 +186,7 @@ class PrefsEditor:
         self.builder = Gtk.Builder()
         self.builder.set_translation_domain(APP_NAME)
         self.keybindings = Keybindings()
+        self.active_message_dialog = None
         try:
             # Figure out where our library is on-disk so we can open our
             (head, _tail) = os.path.split(config.__file__)
@@ -1719,8 +1720,11 @@ class PrefsEditor:
             ).format(accel_label, self.keybindingnames[duplicate_keybinding_name])
             dialog.format_secondary_text(message)
 
+            self.active_message_dialog = dialog
             dialog.run()
             dialog.destroy()
+            self.active_message_dialog = None
+
             return
 
         celliter = liststore.get_iter_from_string(path)

tests/test_prefseditor_keybindings.py

@@ -0,0 +1,180 @@
+import pytest
+import gi
+
+gi.require_version("Gtk", "3.0")
+from gi.repository import Gtk, Gdk, GLib
+
+CONTROL_SHIFT_MOD = Gdk.ModifierType.CONTROL_MASK | Gdk.ModifierType.SHIFT_MASK
+CONTROL_ALT_MOD = Gdk.ModifierType.CONTROL_MASK | Gdk.ModifierType.MOD1_MASK
+CONTROL_ALT_SHIFT_MOD = (
+    Gdk.ModifierType.CONTROL_MASK
+    | Gdk.ModifierType.MOD1_MASK
+    | Gdk.ModifierType.SHIFT_MASK
+)
+
+
+class MessageDialogToken:
+    def __init__(self):
+        self.has_appeared = False
+
+
+def detect_close_message_dialog(prefs_editor, message_dialog_token):
+    # type: (terminatorlib.prefseditor.PrefsEditor, MessageDialogToken) -> bool
+    """
+    Checks whether a message dialog is displayed over the Preferences
+    window and if so, closes it. This function is intended to be used with
+    `GLib.timeout_add_seconds` or a similar function.
+    """
+    if prefs_editor.active_message_dialog is not None:
+        message_dialog_token.has_appeared = True
+        prefs_editor.active_message_dialog.hide()
+        return False
+    return True
+
+
+def reset_config_keybindings():
+    """
+    Resets key bindings to the default.
+
+    Key bindings are stored in `terminatorlib.config.ConfigBase`,
+    which is implemented using the Borg design pattern - this means
+    that simply recreating a `ConfigBase` instance won't reset the key
+    bindings to the default.
+    """
+    from terminatorlib import config
+
+    conf_base = config.ConfigBase()
+    conf_base.keybindings = None
+    conf_base.prepare_attributes()
+
+
+def test_non_empty_default_keybinding_accels_are_distinct():
+    """
+    Tests that all non-empty key binding accelerators defined in
+    the default config are distinct.
+    """
+    from terminatorlib import config
+
+    all_default_accelerators = [
+        Gtk.accelerator_parse(accel)
+        for accel in config.DEFAULTS["keybindings"].values()
+        if accel != ""  # ignore empty key bindings
+    ]
+
+    assert len(all_default_accelerators) == len(set(all_default_accelerators))
+
+
+@pytest.mark.parametrize(
+    "accel_params,expected",
+    [
+        # 1) 'edit_tab_title' Ctrl+Alt+A
+        (("9", 97, CONTROL_ALT_MOD, 38), False,),
+        # 2) 'edit_terminal_title' Ctrl+Alt+A
+        (("10", 97, CONTROL_ALT_MOD, 38), True,),
+        # 3) 'edit_window_title' F11
+        (("11", 65480, Gdk.ModifierType(0), 95), True,),
+        # 4) 'zoom_in' Shift+Ctrl+Z
+        (("70", 122, CONTROL_SHIFT_MOD, 52), True,),
+        # 5) 'close_terminal' Ctrl+Alt+{
+        (("3", 123, CONTROL_ALT_SHIFT_MOD, 34), False,),
+        # 6) 'zoom_in' Shift+Ctrl+B
+        (("70", 98, CONTROL_SHIFT_MOD, 56), False,),
+    ],
+)
+def test_message_dialog_is_shown_on_duplicate_accel_assignment(
+    accel_params, expected
+):
+    """
+    Tests that a message dialog appears every time a duplicate key binding accelerator
+    is attempted to be assigned to a different action in `Preferences > Keybindings`,
+    and doesn't appear if a key binding accelerator is not a duplicate.
+    """
+    from terminatorlib import terminal
+    from terminatorlib import prefseditor
+
+    path, key, mods, code = accel_params
+
+    term = terminal.Terminal()
+    prefs_editor = prefseditor.PrefsEditor(term=term)
+    message_dialog = MessageDialogToken()
+    # Check for an active message dialog every second
+    GLib.timeout_add_seconds(
+        1, detect_close_message_dialog, prefs_editor, message_dialog
+    )
+
+    widget = prefs_editor.builder.get_object("keybindingtreeview")
+    liststore = widget.get_model()
+
+    # Replace default accelerator with a test one
+    prefs_editor.on_cellrenderer_accel_edited(
+        liststore=liststore, path=path, key=key, mods=mods, _code=code
+    )
+
+    assert message_dialog.has_appeared == expected
+
+    reset_config_keybindings()
+
+
+@pytest.mark.parametrize(
+    "accel_params",
+    [
+        # 1) 'edit_tab_title' Ctrl+Alt+A
+        ("9", 97, CONTROL_ALT_MOD, 38),
+        # 2) 'edit_terminal_title' Ctrl+Alt+A
+        ("10", 97, CONTROL_ALT_MOD, 38),
+        # 3) 'edit_window_title' F11
+        ("11", 65480, Gdk.ModifierType(0), 95),
+        # 4) 'zoom_in' Shift+Ctrl+Z
+        ("70", 122, CONTROL_SHIFT_MOD, 52),
+    ],
+)
+def test_duplicate_accels_not_possible_to_set(accel_params):
+    """
+    Tests that a duplicate key binding accelerator, that is a key binding accelerator
+    which is already defined in the config cannot be used to refer to more than
+    one action.
+    """
+    from terminatorlib import config
+    from terminatorlib import terminal
+    from terminatorlib import prefseditor
+
+    path, key, mods, code = accel_params
+
+    term = terminal.Terminal()
+    prefs_editor = prefseditor.PrefsEditor(term=term)
+    message_dialog = MessageDialogToken()
+
+    # Check for an active message dialog every second
+    GLib.timeout_add_seconds(
+        1, detect_close_message_dialog, prefs_editor, message_dialog
+    )
+
+    widget = prefs_editor.builder.get_object("keybindingtreeview")
+    liststore = widget.get_model()
+    binding = liststore.get_value(liststore.get_iter(path), 0)
+
+    all_default_accelerators = {
+        Gtk.accelerator_parse(accel)
+        for accel in config.DEFAULTS["keybindings"].values()
+        if accel != ""  # ignore empty key bindings
+    }
+    # Check that a test accelerator is indeed a duplicate
+    assert (key, mods) in all_default_accelerators
+
+    default_accelerator = Gtk.accelerator_parse(
+        config.DEFAULTS["keybindings"][binding]
+    )
+
+    # Replace default accelerator with a test one
+    prefs_editor.on_cellrenderer_accel_edited(
+        liststore=liststore, path=path, key=key, mods=mods, _code=code
+    )
+
+    new_accelerator = Gtk.accelerator_parse(
+        prefs_editor.config["keybindings"][binding]
+    )
+
+    # Key binding accelerator value shouldn't have changed
+    assert default_accelerator == new_accelerator
+
+    reset_config_keybindings()