Add failing tests.

tests/test_focus.py

@@ -1,3 +1,5 @@
+import pytest
+
 from textual.app import App
 from textual.screen import Screen
 from textual.widget import Widget
@@ -15,6 +17,28 @@ class ChildrenFocusableOnly(Widget, can_focus=False, can_focus_children=True):
     pass
 
 
+@pytest.fixture
+def screen() -> Screen:
+    app = App()
+    app._set_active()
+    app.push_screen(Screen())
+
+    screen = app.screen
+
+    # The classes even/odd alternate along the focus chain.
+    # The classes in/out identify nested widgets.
+    screen._add_children(
+        Focusable(id="foo", classes="a"),
+        NonFocusable(id="bar"),
+        Focusable(Focusable(id="Paul", classes="c"), id="container1", classes="b"),
+        NonFocusable(Focusable(id="Jessica", classes="a"), id="container2"),
+        Focusable(id="baz", classes="b"),
+        ChildrenFocusableOnly(Focusable(id="child", classes="c")),
+    )
+
+    return screen
+
+
 def test_focus_chain():
     app = App()
     app._set_active()
@@ -38,22 +62,7 @@ def test_focus_chain():
     assert focus_chain == ["foo", "container1", "Paul", "baz", "child"]
 
 
-def test_focus_next_and_previous():
-    app = App()
-    app._set_active()
-    app.push_screen(Screen())
-
-    screen = app.screen
-
-    screen._add_children(
-        Focusable(id="foo"),
-        NonFocusable(id="bar"),
-        Focusable(Focusable(id="Paul"), id="container1"),
-        NonFocusable(Focusable(id="Jessica"), id="container2"),
-        Focusable(id="baz"),
-        ChildrenFocusableOnly(Focusable(id="child")),
-    )
-
+def test_focus_next_and_previous(screen: Screen):
     assert screen.focus_next().id == "foo"
     assert screen.focus_next().id == "container1"
     assert screen.focus_next().id == "Paul"
@@ -64,3 +73,95 @@ def test_focus_next_and_previous():
     assert screen.focus_previous().id == "Paul"
     assert screen.focus_previous().id == "container1"
     assert screen.focus_previous().id == "foo"
+
+
+def test_focus_next_and_previous_with_type_selector(screen: Screen):
+    """Move focus with a selector that matches the currently focused node."""
+    screen.set_focus(screen.query_one("#Paul"))
+    assert screen.focused.id == "Paul"
+
+    assert screen.focus_next(Focusable).id == "Jessica"
+    assert screen.focus_next(Focusable).id == "baz"
+    assert screen.focus_next(Focusable).id == "child"
+
+    assert screen.focus_previous(Focusable).id == "baz"
+    assert screen.focus_previous(Focusable).id == "Jessica"
+    assert screen.focus_previous(Focusable).id == "Paul"
+    assert screen.focus_previous(Focusable).id == "container1"
+    assert screen.focus_previous(Focusable).id == "foo"
+
+
+def test_focus_next_and_previous_with_str_selector(screen: Screen):
+    """Move focus with a selector that matches the currently focused node."""
+    screen.set_focus(screen.query_one("#foo"))
+    assert screen.focused.id == "foo"
+
+    assert screen.focus_next(".a").id == "Jessica"
+    assert screen.focus_next("Focusable").id == "baz"
+
+    assert screen.focus_previous(".b").id == "container1"
+
+    assert screen.focus_next("Focusable").id == "Paul"
+    assert screen.focus_next(".c").id == "child"
+
+    assert screen.focus_previous(".c").id == "Paul"
+
+
+def test_focus_next_and_previous_with_type_selector_without_self():
+    """Test moving the focus with a selector that does not match the currently focused node."""
+    app = App()
+    app._set_active()
+    app.push_screen(Screen())
+
+    screen = app.screen
+
+    from textual.containers import Horizontal, Vertical
+    from textual.widgets import Input, Label, Static
+
+    screen._add_children(
+        Vertical(
+            Horizontal(
+                Input(id="w3"),
+                Label(id="w4"),
+                Input(id="w5"),
+                Static(id="w6"),
+                Label(id="w7"),
+                id="w2",
+            ),
+            Horizontal(
+                Static(id="w9"),
+                Label(id="w10"),
+                Static(id="w11"),
+                Input(id="w12"),
+                Input(id="w13"),
+                id="w8",
+            ),
+            id="w1",
+        )
+    )
+
+    screen.set_focus(screen.query_one("#w3"))
+    assert screen.focused.id == "w3"
+
+    assert screen.focus_next(Static).id == "w6"
+    assert screen.focus_next(Label).id == "w7"
+    assert screen.focus_next(Input).id == "w12"
+
+    assert screen.focus_previous(Static).id == "w11"
+    assert screen.focus_previous(Label).id == "w10"
+    assert screen.focus_previous(Static).id == "w9"
+    assert screen.focus_previous(Input).id == "w5"
+
+
+def test_focus_next_and_previous_with_str_selector_without_self(screen: Screen):
+    """Test moving the focus with a selector that does not match the currently focused node."""
+    screen.set_focus(screen.query_one("#foo"))
+    assert screen.focused.id == "foo"
+
+    assert screen.focus_next(".c").id == "Paul"
+    assert screen.focus_next(".b").id == "baz"
+    assert screen.focus_next(".c").id == "child"
+
+    assert screen.focus_previous(".a").id == "Jessica"
+    assert screen.focus_previous(".b").id == "container1"
+    assert screen.focus_previous(".a").id == "foo"