Add unit tests for disabled property and pseudoclass

tests/test_disabled.py

@@ -0,0 +1,80 @@
+"""Test Widget.disabled."""
+
+from textual.app import App, ComposeResult
+from textual.containers import Vertical
+from textual.widgets import (
+    Button,
+    DataTable,
+    DirectoryTree,
+    Input,
+    ListView,
+    Switch,
+    TextLog,
+    Tree,
+)
+
+
+class DisableApp(App[None]):
+    """Application for testing Widget.disable."""
+
+    def compose(self) -> ComposeResult:
+        """Compose the child widgets."""
+        yield Vertical(
+            Button(),
+            DataTable(),
+            DirectoryTree("."),
+            Input(),
+            ListView(),
+            Switch(),
+            TextLog(),
+            Tree("Test"),
+            id="test-container",
+        )
+
+
+async def test_all_initially_enabled() -> None:
+    """All widgets should start out enabled."""
+    async with DisableApp().run_test() as pilot:
+        assert all(
+            not node.disabled for node in pilot.app.screen.query("#test-container > *")
+        )
+
+
+async def test_enabled_widgets_have_enabled_pseudo_class() -> None:
+    """All enabled widgets should have the :enabled pseudoclass."""
+    async with DisableApp().run_test() as pilot:
+        assert all(
+            node.has_pseudo_class("enabled") and not node.has_pseudo_class("disabled")
+            for node in pilot.app.screen.query("#test-container > *")
+        )
+
+
+async def test_all_individually_disabled() -> None:
+    """Post-disable all widgets should report being disabled."""
+    async with DisableApp().run_test() as pilot:
+        for node in pilot.app.screen.query("Vertical > *"):
+            node.disabled = True
+        assert all(
+            node.disabled for node in pilot.app.screen.query("#test-container > *")
+        )
+
+
+async def test_disabled_widgets_have_disabled_pseudo_class() -> None:
+    """All disabled widgets should have the :disabled pseudoclass."""
+    async with DisableApp().run_test() as pilot:
+        for node in pilot.app.screen.query("#test-container > *"):
+            node.disabled = True
+        assert all(
+            node.has_pseudo_class("disabled") and not node.has_pseudo_class("enabled")
+            for node in pilot.app.screen.query("#test-container > *")
+        )
+
+
+async def test_disable_via_container() -> None:
+    """All child widgets should appear (to CSS) as disabled by a container being disabled."""
+    async with DisableApp().run_test() as pilot:
+        pilot.app.screen.query_one("#test-container", Vertical).disabled = True
+        assert all(
+            node.has_pseudo_class("disabled") and not node.has_pseudo_class("enabled")
+            for node in pilot.app.screen.query("#test-container > *")
+        )