fix signal error message and add tests (#2118)

packages/signals/examples/errors.rs

@@ -1,75 +0,0 @@
-use dioxus::prelude::*;
-
-fn main() {
-    launch(app);
-}
-
-#[derive(Clone, Copy)]
-enum ErrorComponent {
-    Read,
-    ReadMut,
-    ReadDropped,
-}
-
-fn app() -> Element {
-    let mut error = use_signal(|| None as Option<ErrorComponent>);
-
-    rsx! {
-        match error() {
-            Some(ErrorComponent::Read) => rsx! { Read {} },
-            Some(ErrorComponent::ReadMut) => rsx! { ReadMut {} },
-            Some(ErrorComponent::ReadDropped) => rsx! { ReadDropped {} },
-            None => rsx! {
-                button { onclick: move |_| error.set(Some(ErrorComponent::Read)), "Read" }
-                button { onclick: move |_| error.set(Some(ErrorComponent::ReadMut)), "ReadMut" }
-                button { onclick: move |_| error.set(Some(ErrorComponent::ReadDropped)), "ReadDropped"}
-            }
-        }
-    }
-}
-
-#[component]
-fn Read() -> Element {
-    let signal = use_signal_sync(|| 0);
-
-    let _write = signal.write_unchecked();
-    let _read = signal.read();
-
-    unreachable!()
-}
-
-#[component]
-fn ReadMut() -> Element {
-    let signal = use_signal_sync(|| 0);
-
-    let _read = signal.read();
-    let _write = signal.write_unchecked();
-
-    unreachable!()
-}
-
-#[component]
-fn ReadDropped() -> Element {
-    let signal = use_signal_sync(|| None as Option<SyncSignal<i32>>);
-
-    if generation() < 4 {
-        needs_update();
-    }
-
-    rsx! {
-        if let Some(value) = signal() {
-            "{value:?}"
-        } else {
-            ReadDroppedSignalChild { parent_signal: signal }
-        }
-    }
-}
-
-#[component]
-fn ReadDroppedSignalChild(parent_signal: SyncSignal<Option<SyncSignal<i32>>>) -> Element {
-    let signal = use_signal_sync(|| 0);
-
-    use_hook(move || parent_signal.set(Some(signal)));
-
-    rsx! { "{signal}" }
-}

packages/signals/src/copy_value.rs

@@ -121,12 +121,14 @@ impl<T: 'static, S: Storage<T>> Readable for CopyValue<T, S> {
     type Target = T;
     type Storage = S;
 
+    #[track_caller]
     fn try_read_unchecked(
         &self,
     ) -> Result<ReadableRef<'static, Self>, generational_box::BorrowError> {
         self.value.try_read()
     }
 
+    #[track_caller]
     fn peek_unchecked(&self) -> ReadableRef<'static, Self> {
         self.value.read()
     }

packages/signals/src/read.rs

@@ -67,6 +67,7 @@ pub trait Readable {
     /// Get a reference to the value without checking the lifetime. This will subscribe the current scope to the signal.
     ///
     /// NOTE: This method is completely safe because borrow checking is done at runtime.
+    #[track_caller]
     fn read_unchecked(&self) -> ReadableRef<'static, Self> {
         self.try_read_unchecked().unwrap()
     }

packages/signals/src/write.rs

@@ -52,6 +52,7 @@ pub trait Writable: Readable {
     /// Get a mutable reference to the value without checking the lifetime. This will update any subscribers.
     ///
     /// NOTE: This method is completely safe because borrow checking is done at runtime.
+    #[track_caller]
     fn write_unchecked(&self) -> WritableRef<'static, Self> {
         self.try_write_unchecked().unwrap()
     }
@@ -114,11 +115,13 @@ pub trait Writable: Readable {
 /// An extension trait for Writable<Option<T>> that provides some convenience methods.
 pub trait WritableOptionExt<T: 'static>: Writable<Target = Option<T>> {
     /// Gets the value out of the Option, or inserts the given value if the Option is empty.
+    #[track_caller]
     fn get_or_insert(&mut self, default: T) -> WritableRef<'_, Self, T> {
         self.get_or_insert_with(|| default)
     }
 
     /// Gets the value out of the Option, or inserts the value returned by the given function if the Option is empty.
+    #[track_caller]
     fn get_or_insert_with(&mut self, default: impl FnOnce() -> T) -> WritableRef<'_, Self, T> {
         let is_none = self.read().is_none();
         if is_none {