Test for Input.select_on_focus interaction with AppBlur and AppFocus

Author: darrenburns

tests/input/test_select_on_focus.py

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+"""The standard path of selecting text on focus is well covered by snapshot tests."""
+
+from textual import events
+from textual.app import App, ComposeResult
+from textual.widgets import Input
+from textual.widgets.input import Selection
+
+
+class InputApp(App[None]):
+    """An app with an input widget."""
+
+    def compose(self) -> ComposeResult:
+        yield Input("Hello, world!")
+
+
+async def test_focus_from_app_focus_does_not_select():
+    """When an Input has focused and the *app* is blurred and then focused (e.g. by pressing
+    alt+tab or focusing another terminal pane), then the content of the Input should not be
+    fully selected when `Input.select_on_focus=True`.
+    """
+    async with InputApp().run_test() as pilot:
+        input_widget = pilot.app.query_one(Input)
+        input_widget.focus()
+        input_widget.selection = Selection.cursor(0)
+        assert input_widget.selection == Selection.cursor(0)
+        pilot.app.post_message(events.AppBlur())
+        await pilot.pause()
+        pilot.app.post_message(events.AppFocus())
+        await pilot.pause()
+        assert input_widget.selection == Selection.cursor(0)