feat: add optional "finally" callback after promise completion

src/core/toast.ts

@@ -34,11 +34,11 @@ const createToast = (
 
 const createHandler =
   (type?: ToastType): ToastHandler =>
-  (message, options) => {
-    const toast = createToast(message, type, options);
-    dispatch({ type: ActionType.UPSERT_TOAST, toast });
-    return toast.id;
-  };
+    (message, options) => {
+      const toast = createToast(message, type, options);
+      dispatch({ type: ActionType.UPSERT_TOAST, toast });
+      return toast.id;
+    };
 
 const toast = (message: Message, opts?: ToastOptions) =>
   createHandler('blank')(message, opts);
@@ -64,6 +64,7 @@ toast.promise = <T>(
     loading: Renderable;
     success: ValueOrFunction<Renderable, T>;
     error: ValueOrFunction<Renderable, any>;
+    finally?: () => void;
   },
   opts?: DefaultToastOptions
 ) => {
@@ -84,7 +85,8 @@ toast.promise = <T>(
         ...opts,
         ...opts?.error,
       });
-    });
+    })
+    .finally(msgs.finally);
 
   return promise;
 };

test/toast.test.tsx

@@ -155,6 +155,67 @@ test('promise toast error', async () => {
   });
 });
 
+test('promise toast finally', async () => {
+  const WAIT_DELAY = 1000;
+  const finallyCallback = jest.fn();
+  const originalPromise = jest.spyOn(toast, 'promise');
+
+
+  render(
+    <>
+      <button
+        type="button"
+        onClick={() => {
+          const sleep = new Promise((resolve) => {
+            setTimeout(resolve, WAIT_DELAY);
+          });
+
+          toast.promise(sleep, {
+            loading: 'Loading...',
+            success: 'Success!',
+            error: 'Error!',
+            finally: finallyCallback
+          });
+        }}
+      >
+        Notify!
+      </button>
+      <Toaster />
+    </>
+  );
+
+  act(() => {
+    fireEvent.click(screen.getByRole('button', { name: /Notify/i }));
+  });
+
+  await screen.findByText(/loading/i);
+
+  expect(screen.queryByText(/loading/i)).toBeInTheDocument();
+
+  waitTime(WAIT_DELAY);
+
+  await waitFor(() => {
+    expect(screen.queryByText(/success/i)).toBeInTheDocument();
+  });
+
+  // Assert that the original `toast.promise` was called with the expected arguments
+  expect(originalPromise).toHaveBeenCalledWith(expect.any(Promise), {
+    loading: 'Loading...',
+    success: 'Success!',
+    error: 'Error!',
+    finally: finallyCallback,
+  });
+
+  // Access the arguments passed to the original `toast.promise` call
+  const [promiseArg, optionsArg] = originalPromise.mock.calls[0];
+
+  // Resolve the promise to trigger the finally callback
+  await promiseArg;
+
+  // Assert that finallyCallback was called
+  expect(finallyCallback).toHaveBeenCalled();
+});
+
 test('error toast with custom duration', async () => {
   render(
     <>