fix: focus correctly when loading help screen (#141)

Signed-off-by: Henry Schreiner <[email protected]>

Author: henryiii

src/uproot_browser/tui/help.py

@@ -39,7 +39,7 @@ def compose(self) -> textual.app.ComposeResult:
                 yield textual.widgets.Button("Done", variant="primary", id="help-done")
 
     def on_mount(self) -> None:
-        self.query_one(textual.widgets.Markdown).focus()
+        self.query_one("#help-text", textual.widgets.MarkdownViewer).focus()
 
     def on_button_pressed(self, _event: textual.widgets.Button.Pressed) -> None:
         self.app.pop_screen()

tests/test_tui.py

@@ -34,3 +34,13 @@ async def test_browse_empty_vim() -> None:
     ).run_test() as pilot:
         await pilot.press("j", "l", "j", "enter")
         assert pilot.app.query_one("#main-view").current == "empty"
+
+
+async def test_help_focus() -> None:
+    async with Browser(
+        Path(skhep_testdata.data_path("uproot-empty.root"))
+    ).run_test() as pilot:
+        await pilot.press("?")
+        focus_chain = [widget.id for widget in pilot.app.screen.focus_chain]
+        assert focus_chain == ["help-text", None, "help-done"]
+        assert pilot.app.screen.focused.id == "help-text"