Test different Theme variants in styling example

examples/styling/src/main.rs

@@ -167,3 +167,42 @@ impl Styling {
         self.theme.clone()
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use rayon::prelude::*;
+
+    use iced_test::{Error, simulator};
+
+    #[test]
+    #[ignore]
+    fn it_showcases_every_theme() -> Result<(), Error> {
+        Theme::ALL
+            .par_iter()
+            .map(|theme| {
+                let mut styling = Styling::default();
+                styling.update(Message::ThemeChanged(theme.clone()));
+
+                let theme = styling.theme();
+
+                let mut ui = simulator(styling.view());
+
+                let snapshot = ui.snapshot(&theme)?;
+
+                assert!(
+                    snapshot.matches_hash(format!(
+                        "snapshots/{theme}",
+                        theme = theme
+                            .to_string()
+                            .to_ascii_lowercase()
+                            .replace(" ", "_")
+                    ))?,
+                    "snapshots for {theme} should match!"
+                );
+
+                Ok(())
+            })
+            .collect()
+    }
+}