copy join flash when falling back to redirect (#3764)

* copy join flash when falling back to redirect

Fixes #3686.

* add e2e test

* actually put test liveview in separate live_session

Author: SteffenDE

assets/js/phoenix_live_view/view.js

@@ -850,7 +850,7 @@ export default class View {
       return
     } else if(resp.reason === "unauthorized" || resp.reason === "stale"){
       this.log("error", () => ["unauthorized live_redirect. Falling back to page request", resp])
-      this.onRedirect({to: this.root.href})
+      this.onRedirect({to: this.root.href, flash: this.flash})
       return
     }
     if(resp.redirect || resp.live_redirect){

test/e2e/support/issues/issue_3686.ex

@@ -0,0 +1,56 @@
+defmodule Phoenix.LiveViewTest.E2E.Issue3686.ALive do
+  use Phoenix.LiveView
+
+  def render(assigns) do
+    ~H"""
+    <h1>A</h1>
+    <button phx-click="go">To B</button>
+
+    <div id="flash">
+      {inspect(@flash)}
+    </div>
+    """
+  end
+
+  def handle_event("go", _unsigned_params, socket) do
+    {:noreply, socket |> put_flash(:info, "Flash from A") |> push_navigate(to: "/issues/3686/b")}
+  end
+end
+
+defmodule Phoenix.LiveViewTest.E2E.Issue3686.BLive do
+  use Phoenix.LiveView
+
+  def render(assigns) do
+    ~H"""
+    <h1>B</h1>
+    <button phx-click="go">To C</button>
+
+    <div id="flash">
+      {inspect(@flash)}
+    </div>
+    """
+  end
+
+  def handle_event("go", _unsigned_params, socket) do
+    {:noreply, socket |> put_flash(:info, "Flash from B") |> redirect(to: "/issues/3686/c")}
+  end
+end
+
+defmodule Phoenix.LiveViewTest.E2E.Issue3686.CLive do
+  use Phoenix.LiveView
+
+  def render(assigns) do
+    ~H"""
+    <h1>C</h1>
+    <button phx-click="go">To A</button>
+
+    <div id="flash">
+      {inspect(@flash)}
+    </div>
+    """
+  end
+
+  def handle_event("go", _unsigned_params, socket) do
+    {:noreply, socket |> put_flash(:info, "Flash from C") |> push_navigate(to: "/issues/3686/a")}
+  end
+end

test/e2e/test_helper.exs

@@ -114,6 +114,7 @@ defmodule Phoenix.LiveViewTest.E2E.Router do
   pipeline :browser do
     plug :accepts, ["html"]
     plug :fetch_session
+    plug :fetch_live_flash
     plug :protect_from_forgery
     plug :put_root_layout, html: {Phoenix.LiveViewTest.E2E.Layout, :root}
   end
@@ -163,12 +164,22 @@ defmodule Phoenix.LiveViewTest.E2E.Router do
       live "/3656", Issue3656Live
       live "/3658", Issue3658Live
       live "/3684", Issue3684Live
+      live "/3686/a", Issue3686.ALive
+      live "/3686/b", Issue3686.BLive
       live "/3709", Issue3709Live
       live "/3709/:id", Issue3709Live
       live "/3719", Issue3719Live
     end
   end
 
+  live_session :other, layout: {Phoenix.LiveViewTest.E2E.Layout, :live} do
+    scope "/issues", Phoenix.LiveViewTest.E2E do
+      pipe_through(:browser)
+
+      live "/3686/c", Issue3686.CLive
+    end
+  end
+
   live_session :navigation, layout: {Phoenix.LiveViewTest.E2E.Navigation.Layout, :live} do
     scope "/navigation" do
       pipe_through(:browser)

test/e2e/tests/issues/3686.spec.js

@@ -0,0 +1,21 @@
+const {test, expect} = require("../../test-fixtures")
+const {syncLV} = require("../../utils")
+
+// https://github.com/phoenixframework/phoenix_live_view/issues/3686
+test("flash is copied across fallback redirect", async ({page}) => {
+  await page.goto("/issues/3686/a")
+  await syncLV(page)
+  await expect(page.locator("#flash")).toHaveText("%{}")
+
+  await page.getByRole("button", {name: "To B"}).click()
+  await syncLV(page)
+  await expect(page.locator("#flash")).toContainText("Flash from A")
+
+  await page.getByRole("button", {name: "To C"}).click()
+  await syncLV(page)
+  await expect(page.locator("#flash")).toContainText("Flash from B")
+
+  await page.getByRole("button", {name: "To A"}).click()
+  await syncLV(page)
+  await expect(page.locator("#flash")).toContainText("Flash from C")
+})