Own browser UI sessions and shared navigation

test/apps/browser/BrowserUiScope.unit.spec.ts

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+import { createServiceContext } from "@vrtmrz/livesync-commonlib/context";
+import { EVENT_PLUGIN_UNLOADED } from "@vrtmrz/livesync-commonlib/compat/events/coreEvents";
+import { describe, expect, it, vi } from "vitest";
+import { createBrowserUiScope } from "@/apps/browser/BrowserUiScope";
+
+describe("browser UI scope", () => {
+    it("owns its document and cancellation independently from another application", () => {
+        const firstContext = createServiceContext();
+        const secondContext = createServiceContext();
+        const firstDocument = {} as Document;
+        const secondDocument = {} as Document;
+        const first = createBrowserUiScope(firstContext, { document: firstDocument });
+        const second = createBrowserUiScope(secondContext, { document: secondDocument });
+        const abort = vi.fn();
+        first.signal.addEventListener("abort", abort);
+        firstContext.events.emitEvent(EVENT_PLUGIN_UNLOADED);
+        firstContext.events.emitEvent(EVENT_PLUGIN_UNLOADED);
+        expect(first.document).toBe(firstDocument);
+        expect(second.document).toBe(secondDocument);
+        expect(first.signal.aborted).toBe(true);
+        expect(first.signal.reason).toEqual(new Error("Plug-in unloaded"));
+        expect(second.signal.aborted).toBe(false);
+        expect(abort).toHaveBeenCalledOnce();
+        secondContext.events.emitEvent(EVENT_PLUGIN_UNLOADED);
+    });
+    it("forwards parent cancellation and unregisters the context subscription", () => {
+        const context = createServiceContext();
+        const parent = new AbortController();
+        const unregister = vi.fn();
+        const once = vi.spyOn(context.events, "onceEvent").mockReturnValue(unregister);
+        const scope = createBrowserUiScope(context, { signal: parent.signal });
+        const reason = new Error("fixture host ended");
+        parent.abort(reason);
+        expect(scope.signal.aborted).toBe(true);
+        expect(scope.signal.reason).toBe(reason);
+        expect(unregister).toHaveBeenCalledOnce();
+        once.mockRestore();
+    });
+    it("removes the parent listener on unload and does not subscribe an already aborted parent", () => {
+        const context = createServiceContext();
+        const parent = new AbortController();
+        const remove = vi.spyOn(parent.signal, "removeEventListener");
+        const scope = createBrowserUiScope(context, { signal: parent.signal });
+        context.events.emitEvent(EVENT_PLUGIN_UNLOADED);
+        expect(remove).toHaveBeenCalledWith("abort", expect.any(Function));
+        const reason = scope.signal.reason;
+        parent.abort(new Error("later"));
+        expect(scope.signal.reason).toBe(reason);
+        const closedContext = createServiceContext();
+        const subscribe = vi.spyOn(closedContext.events, "onceEvent");
+        const closed = createBrowserUiScope(closedContext, { signal: parent.signal });
+        expect(closed.signal.aborted).toBe(true);
+        expect(closed.signal.reason).toBe(parent.signal.reason);
+        expect(subscribe).not.toHaveBeenCalled();
+    });
+});