tests

tests/test_recompose.py

@@ -0,0 +1,46 @@
+from textual.app import App, ComposeResult
+from textual.containers import Vertical
+from textual.widgets import Input, Label
+
+
+async def test_recompose_preserve_id():
+    """Check recomposing leaves widgets with matching ID."""
+
+    class MyVertical(Vertical):
+        def compose(self) -> ComposeResult:
+            yield Label("foo", classes="foo", name="foo")
+            yield Input(id="bar", name="bar")
+            yield Label("baz", classes="baz", name="baz")
+
+    class RecomposeApp(App):
+        def compose(self) -> ComposeResult:
+            yield MyVertical()
+
+    app = RecomposeApp()
+    async with app.run_test() as pilot:
+        foo = app.query_one(".foo")
+        bar = app.query_one("#bar")
+        baz = app.query_one(".baz")
+        assert [node.name for node in app.query("MyVertical > *")] == [
+            "foo",
+            "bar",
+            "baz",
+        ]
+
+        bar.focus()
+        await pilot.press("h", "i")
+        await app.query_one(MyVertical).recompose()
+
+        # Order shouldn't change
+        assert [node.name for node in app.query("MyVertical > *")] == [
+            "foo",
+            "bar",
+            "baz",
+        ]
+
+        # Check that only the ID is the same instance
+        assert app.query_one(".foo") is not foo  # New instance
+        assert app.query_one("#bar") is bar  # Matching id, so old instance
+        assert app.query_one(".baz") is not baz  # new instance
+
+        assert app.query_one("#bar", Input).value == "hi"