Add Refreshable trait

packages/effect-fc-next/test/Refreshable.test.ts

@@ -0,0 +1,40 @@
+import { describe, expect, it, vi } from "vitest"
+import * as Refreshable from "../src/Refreshable.js"
+
+
+describe("Refreshable", () => {
+    it("attaches a cell and notifies subscribers after a compatible update", async () => {
+        const first = {}
+        const cell = Refreshable.makeCell(first, "hooks", false)
+        const listener = vi.fn()
+
+        expect(Refreshable.isRefreshable(first)).toBe(false)
+        const attached = Refreshable.attach(first, cell)
+        expect(attached).toBe(first)
+        expect(Refreshable.isRefreshable(first)).toBe(true)
+        expect(attached[Refreshable.RefreshableTypeId]).toBe(cell)
+
+        cell.subscribe(listener)
+        const second = {}
+        cell.update(second, "hooks", false)
+
+        expect(cell.current).toBe(second)
+        expect(cell.snapshot).toEqual({
+            revision: 1,
+            resetRevision: 0,
+        })
+
+        await Promise.resolve()
+        expect(listener).toHaveBeenCalledTimes(1)
+    })
+
+    it("requests a remount when a signature changes or reset is forced", () => {
+        const cell = Refreshable.makeCell({}, "one", false)
+
+        cell.update({}, "two", false)
+        expect(cell.snapshot.resetRevision).toBe(1)
+
+        cell.update({}, "two", true)
+        expect(cell.snapshot.resetRevision).toBe(2)
+    })
+})