Add persisting tests

packages/backend-core/src/cache/tests/docWritethrough.spec.ts

@@ -33,7 +33,7 @@ describe("docWritethrough", () => {
       docWritethrough = new DocWritethrough(db, documentId, WRITE_RATE_MS)
     })
 
-    it("patching will not persist until timeout is hit", async () => {
+    it("patching will not persist if timeout does not hit", async () => {
       await config.doInTenant(async () => {
         await docWritethrough.patch(generatePatchObject(2))
         await docWritethrough.patch(generatePatchObject(2))
@@ -43,5 +43,42 @@ describe("docWritethrough", () => {
         expect(await db.docExists(documentId)).toBe(false)
       })
     })
+
+    it("patching will persist if timeout hits and next patch is called", async () => {
+      await config.doInTenant(async () => {
+        const patch1 = generatePatchObject(2)
+        const patch2 = generatePatchObject(2)
+        await docWritethrough.patch(patch1)
+        await docWritethrough.patch(patch2)
+
+        tk.travel(Date.now() + WRITE_RATE_MS)
+
+        const patch3 = generatePatchObject(3)
+        await docWritethrough.patch(patch3)
+
+        expect(await db.get(documentId)).toEqual({
+          _id: documentId,
+          ...patch1,
+          ...patch2,
+          ...patch3,
+          _rev: expect.stringMatching(/1-.+/),
+          createdAt: new Date(initialTime + 500).toISOString(),
+          updatedAt: new Date(initialTime + 500).toISOString(),
+        })
+      })
+    })
+
+    it("patching will not persist even if timeout hits but next patch is not callec", async () => {
+      await config.doInTenant(async () => {
+        const patch1 = generatePatchObject(2)
+        const patch2 = generatePatchObject(2)
+        await docWritethrough.patch(patch1)
+        await docWritethrough.patch(patch2)
+
+        tk.travel(Date.now() + WRITE_RATE_MS)
+
+        expect(await db.docExists(documentId)).toBe(false)
+      })
+    })
   })
 })