Initialize session state by page and module identity

e2e/fixtures/keyed-state-probe.js

@@ -0,0 +1,38 @@
+// Rôle : observe les valeurs validées et les setters différés d'un état lié à une clé.
+/* global sessionStorage */
+import { createElement, StrictMode, useLayoutEffect } from "react";
+import { createRoot } from "react-dom/client";
+import { flushSync } from "react-dom";
+import { useKeyedState } from "../../website/src/hooks/useKeyedState.js";
+
+export function mountKeyedStateProbe(element) {
+  const root = createRoot(element);
+  const snapshots = [];
+  const setters = new Map();
+  let reads = 0;
+
+  function Probe({ identity }) {
+    const [value, setValue] = useKeyedState(identity, (key) => {
+      reads++;
+      return JSON.parse(sessionStorage.getItem(`keyed-probe:${key}`) || "[]");
+    });
+    useLayoutEffect(() => {
+      snapshots.push({ key: identity, value });
+      setters.set(identity, setValue);
+    });
+    return createElement("output", null, JSON.stringify(value));
+  }
+
+  function update(identity) {
+    snapshots.length = 0;
+    flushSync(() => root.render(createElement(StrictMode, null, createElement(Probe, { identity }))));
+  }
+  update("a");
+  return {
+    update,
+    snapshots,
+    get reads() { return reads; },
+    append: (key, value) => flushSync(() => setters.get(key)((current) => [...current, value])),
+    unmount: () => root.unmount()
+  };
+}