focus traversal

tests/test_focus.py

@@ -0,0 +1,71 @@
+from textual.app import App
+from textual.screen import Screen
+from textual.widget import Widget
+
+
+class Focusable(Widget, can_focus=True):
+    pass
+
+
+class NonFocusable(Widget, can_focus=False):
+    pass
+
+
+def test_focus_chain():
+
+    app = App()
+    app.push_screen(Screen())
+
+    # Check empty focus chain
+    assert not app.focus_chain
+
+    app.screen.add_children(
+        Focusable(id="foo"),
+        NonFocusable(id="bar"),
+        Focusable(Focusable(id="Paul"), id="container1"),
+        NonFocusable(Focusable(id="Jessica"), id="container2"),
+        Focusable(id="baz"),
+    )
+
+    focused = [widget.id for widget in app.focus_chain]
+    assert focused == ["foo", "Paul", "baz"]
+
+
+def test_show_focus():
+    app = App()
+    app.push_screen(Screen())
+    app.screen.add_children(
+        Focusable(id="foo"),
+        NonFocusable(id="bar"),
+        Focusable(Focusable(id="Paul"), id="container1"),
+        NonFocusable(Focusable(id="Jessica"), id="container2"),
+        Focusable(id="baz"),
+    )
+
+    focused = [widget.id for widget in app.focus_chain]
+    assert focused == ["foo", "Paul", "baz"]
+
+    assert app.focused is None
+    assert not app.has_class("-show-focus")
+    app.show_focus()
+    assert app.has_class("-show-focus")
+
+
+def test_focus_next_and_previous():
+
+    app = App()
+    app.push_screen(Screen())
+    app.screen.add_children(
+        Focusable(id="foo"),
+        NonFocusable(id="bar"),
+        Focusable(Focusable(id="Paul"), id="container1"),
+        NonFocusable(Focusable(id="Jessica"), id="container2"),
+        Focusable(id="baz"),
+    )
+
+    assert app.focus_next().id == "foo"
+    assert app.focus_next().id == "Paul"
+    assert app.focus_next().id == "baz"
+
+    assert app.focus_previous().id == "Paul"
+    assert app.focus_previous().id == "foo"