[tests] Working on an integration test for the vertical layout

sandbox/color_names.py

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+import rich.repr
+from rich.align import Align
+from rich.console import RenderableType
+from rich.panel import Panel
+from rich.pretty import Pretty
+
+from textual._color_constants import COLOR_NAME_TO_RGB
+from textual.app import App, ComposeResult
+from textual.widget import Widget
+from textual.widgets import Placeholder
+
+
+@rich.repr.auto(angular=False)
+class ColorDisplay(Widget, can_focus=True):
+    def render(self) -> RenderableType:
+        return Panel(
+            Align.center(
+                Pretty(self, no_wrap=True, overflow="ellipsis"), vertical="middle"
+            ),
+            title=self.name,
+            border_style="none",
+        )
+
+
+class ColorNames(App):
+    CSS = """
+    ColorDisplay {
+        height: 1;
+    }
+    """
+
+    def on_mount(self):
+        self.bind("q", "quit")
+
+    def compose(self) -> ComposeResult:
+        for color_name, color in COLOR_NAME_TO_RGB.items():
+            color_placeholder = ColorDisplay(name=color_name)
+            is_dark_color = sum(color) < 400
+            color_placeholder.styles.color = "white" if is_dark_color else "black"
+            color_placeholder.styles.background = color_name
+            yield color_placeholder
+
+
+if __name__ == "__main__":
+    color_name_app = ColorNames()
+    color_name_app.run()