test: add regression test for #4296

examples/regression/e2e/features/issue_4296.feature

@@ -0,0 +1,18 @@
+@check_issue_4296
+Feature: Check that issue 4296 does not reappear
+
+	Scenario: Query param signals created in LazyRoute::data() are reactive in ::view().
+		Given I see the app
+		And I can access regression test 4296
+		Then I see the result is the string None
+		When I select the link abc
+		Then I see the result is the string Some("abc")
+		When I select the link def
+		Then I see the result is the string Some("def")
+
+	Scenario: Loading page with query signal works as well.
+		Given I see the app
+		And I can access regression test 4296
+		When I select the link abc
+		When I reload the page
+		Then I see the result is the string Some("abc")

examples/regression/src/app.rs

@@ -1,6 +1,7 @@
 use crate::{
     issue_4005::Routes4005, issue_4088::Routes4088, issue_4217::Routes4217,
-    issue_4285::Routes4285, pr_4015::Routes4015, pr_4091::Routes4091,
+    issue_4285::Routes4285, issue_4296::Routes4296, pr_4015::Routes4015,
+    pr_4091::Routes4091,
 };
 use leptos::prelude::*;
 use leptos_meta::{MetaTags, *};
@@ -45,6 +46,7 @@ pub fn App() -> impl IntoView {
                     <Routes4217/>
                     <Routes4005/>
                     <Routes4285/>
+                    <Routes4296/>
                 </Routes>
             </main>
         </Router>
@@ -70,6 +72,7 @@ fn HomePage() -> impl IntoView {
                 <li><a href="/4217/">"4217"</a></li>
                 <li><a href="/4005/">"4005"</a></li>
                 <li><a href="/4285/">"4285"</a></li>
+                <li><a href="/4296/">"4296"</a></li>
             </ul>
         </nav>
     }

examples/regression/src/issue_4296.rs

@@ -0,0 +1,36 @@
+use leptos::prelude::*;
+#[allow(unused_imports)]
+use leptos_router::{
+    components::Route, path, Lazy, MatchNestedRoutes, NavigateOptions,
+};
+use leptos_router::{hooks::use_query_map, LazyRoute};
+
+#[component]
+pub fn Routes4296() -> impl MatchNestedRoutes + Clone {
+    view! {
+        <Route path=path!("4296") view={Lazy::<Issue4296>::new()}/>
+    }
+    .into_inner()
+}
+
+struct Issue4296 {
+    query: Signal<Option<String>>,
+}
+
+impl LazyRoute for Issue4296 {
+    fn data() -> Self {
+        let query = use_query_map();
+        let query = Signal::derive(move || query.read().get("q"));
+        Self { query }
+    }
+
+    async fn view(this: Self) -> AnyView {
+        let Issue4296 { query } = this;
+        view! {
+            <a href="?q=abc">"abc"</a>
+            <a href="?q=def">"def"</a>
+            <p id="result">{move || format!("{:?}", query.get())}</p>
+        }
+        .into_any()
+    }
+}

examples/regression/src/lib.rs

@@ -3,6 +3,7 @@ mod issue_4005;
 mod issue_4088;
 mod issue_4217;
 mod issue_4285;
+mod issue_4296;
 mod pr_4015;
 mod pr_4091;