Deduplicate suspensions when considering subsequent renders for suspensions (#3099)

* FIx duplicate suspension.

* Fix tests.

* Fix tests.

* Fix tests.

packages/yew/src/suspense/component.rs

@@ -87,6 +87,11 @@ mod feat_csr_ssr {
                         return false;
                     }
 
+                    // If a suspension already exists, ignore it.
+                    if self.suspensions.iter().any(|n| n == &m) {
+                        return false;
+                    }
+
                     self.suspensions.push(m);
 
                     true

packages/yew/tests/suspense.rs

@@ -786,3 +786,40 @@ async fn resume_after_unmount() {
     let result = obtain_result();
     assert_eq!(result.as_str(), "<div>Content replacement</div>");
 }
+
+#[wasm_bindgen_test]
+async fn test_duplicate_suspension() {
+    use yew::html::ChildrenProps;
+
+    #[function_component]
+    fn FetchingProvider(props: &ChildrenProps) -> HtmlResult {
+        use_future(|| async {
+            sleep(Duration::ZERO).await;
+        })?;
+        Ok(html! { <>{props.children.clone()}</> })
+    }
+
+    #[function_component]
+    fn Child() -> Html {
+        html! {<div id="result">{"hello!"}</div>}
+    }
+
+    #[function_component]
+    fn App() -> Html {
+        let fallback = Html::default();
+        html! {
+           <Suspense {fallback}>
+                <FetchingProvider>
+                    <Child />
+                </FetchingProvider>
+           </Suspense>
+        }
+    }
+
+    yew::Renderer::<App>::with_root(gloo::utils::document().get_element_by_id("output").unwrap())
+        .render();
+
+    sleep(Duration::from_millis(50)).await;
+    let result = obtain_result();
+    assert_eq!(result.as_str(), "hello!");
+}