,,

frontend/sync-client/src/services/sync-service.test.ts

@@ -20,7 +20,10 @@ test("paused sync sends no requests, while connection checks still work", async
     let requests = 0;
     const service = new SyncService("device", settings(), async () => {
         requests++;
-        return Response.json({ headEventId: 0, events: [] });
+        return Response.json(
+            { headEventId: 0, endEventId: 0, events: [] },
+            { headers: { "X-Vault-Link-History": "0:empty" } }
+        );
     }, { get: () => undefined, save: async () => { } });
     await assert.rejects(service.getEvents(0), SyncResetError);
     assert.equal(requests, 0);
@@ -42,7 +45,10 @@ test("pause aborts requests and fences late responses from an injected fetch", a
             signals.push(init!.signal!);
             return signals.length === 1
                 ? response.promise
-                : Response.json({ headEventId: 0, events: [] });
+                : Response.json(
+                    { headEventId: 0, endEventId: 0, events: [] },
+                    { headers: { "X-Vault-Link-History": "0:empty" } }
+                );
         },
         {
             get: () => undefined,
@@ -66,7 +72,7 @@ test("pause aborts requests and fences late responses from an injected fetch", a
         )
     );
     await new Promise((resolve) => setImmediate(resolve));
-    assert.deepEqual(saved, []);
+    assert.deepEqual(saved, ["0:empty"]);
 });
 
 for (const binary of [false, true]) {
@@ -179,3 +185,32 @@ test("history saves only new checkpoints, including a changed token at the same
     }
     assert.deepEqual(saved, ["1:first", "2:next", "2:replacement"]);
 });
+
+for (const checkpoint of [undefined, ""]) {
+    test(`successful sync responses reject ${checkpoint === undefined ? "missing" : "empty"} history checkpoints`, async () => {
+        const service = new SyncService(
+            "device",
+            settings(),
+            async () =>
+                Response.json(
+                    { headEventId: 0, endEventId: 0, events: [] },
+                    {
+                        headers: checkpoint === undefined
+                            ? {}
+                            : { "X-Vault-Link-History": checkpoint }
+                    }
+                ),
+            {
+                get: (): undefined => undefined,
+                save: async (): Promise<void> => {
+                    assert.fail("must not save a missing checkpoint");
+                }
+            }
+        );
+        service.resume();
+        await assert.rejects(
+            service.getEvents(0),
+            /Missing server history checkpoint/
+        );
+    });
+}