diff --git a/src/lib/queries/useQuery$.reactivity.test.tsx b/src/lib/queries/useQuery$.reactivity.test.tsx
index 192dd09..cf51e65 100644
--- a/src/lib/queries/useQuery$.reactivity.test.tsx
+++ b/src/lib/queries/useQuery$.reactivity.test.tsx
@@ -1,10 +1,10 @@
 import { act, render, screen } from "@testing-library/react"
-import { BehaviorSubject, filter, map, switchMap } from "rxjs"
+import { BehaviorSubject } from "rxjs"
 import { describe, expect, it } from "vitest"
 import {
+  createLiveQueryFn,
   createQueryClient,
   createWrapper,
-  isDefined,
   liveQueryOptions,
 } from "../../tests/liveQuery"
 import { waitForTimeout } from "../../tests/utils"
@@ -20,12 +20,7 @@ describe("useQuery$ live-query reactivity", () => {
       const { data } = useQuery$({
         ...liveQueryOptions,
         queryKey: ["live", "add"],
-        queryFn: () =>
-          db$.pipe(
-            filter(isDefined),
-            switchMap(() => liveQuery$),
-            map((items) => [...items]),
-          ),
+        queryFn: createLiveQueryFn(db$, liveQuery$),
       })
 
       return <span data-testid="data">{JSON.stringify(data)}</span>
@@ -60,12 +55,7 @@ describe("useQuery$ live-query reactivity", () => {
       const { data } = useQuery$({
         ...liveQueryOptions,
         queryKey: ["live", "remove"],
-        queryFn: () =>
-          db$.pipe(
-            filter(isDefined),
-            switchMap(() => liveQuery$),
-            map((items) => [...items]),
-          ),
+        queryFn: createLiveQueryFn(db$, liveQuery$),
       })
 
       return <span data-testid="data">{JSON.stringify(data)}</span>
@@ -100,12 +90,7 @@ describe("useQuery$ live-query reactivity", () => {
       return useQuery$({
         ...liveQueryOptions,
         queryKey: ["live", "double"],
-        queryFn: () =>
-          db$.pipe(
-            filter(isDefined),
-            switchMap(() => liveQuery$),
-            map((items) => [...items]),
-          ),
+        queryFn: createLiveQueryFn(db$, liveQuery$),
       })
     }
 
@@ -145,12 +130,7 @@ describe("useQuery$ live-query reactivity", () => {
       const { data } = useQuery$({
         ...liveQueryOptions,
         queryKey: ["live", "rapid"],
-        queryFn: () =>
-          db$.pipe(
-            filter(isDefined),
-            switchMap(() => liveQuery$),
-            map((items) => [...items]),
-          ),
+        queryFn: createLiveQueryFn(db$, liveQuery$),
       })
 
       return <span data-testid="data">{JSON.stringify(data)}</span>
@@ -186,12 +166,7 @@ describe("useQuery$ live-query reactivity", () => {
         networkMode: "always",
         gcTime: 0,
         queryKey: ["live", "external-refetch"],
-        queryFn: () =>
-          db$.pipe(
-            filter(isDefined),
-            switchMap(() => liveQuery$),
-            map((items) => [...items]),
-          ),
+        queryFn: createLiveQueryFn(db$, liveQuery$),
       })
 
       return <span data-testid="data">{JSON.stringify(data)}</span>
@@ -231,12 +206,7 @@ describe("useQuery$ live-query reactivity", () => {
         networkMode: "always",
         gcTime: 0,
         queryKey: ["live", "invalidate"],
-        queryFn: () =>
-          db$.pipe(
-            filter(isDefined),
-            switchMap(() => liveQuery$),
-            map((items) => [...items]),
-          ),
+        queryFn: createLiveQueryFn(db$, liveQuery$),
       })
 
       return <span data-testid="data">{JSON.stringify(data)}</span>
diff --git a/src/lib/queries/useQuery$.unmount.test.tsx b/src/lib/queries/useQuery$.unmount.test.tsx
index e553718..c0d8190 100644
--- a/src/lib/queries/useQuery$.unmount.test.tsx
+++ b/src/lib/queries/useQuery$.unmount.test.tsx
@@ -1,11 +1,11 @@
 import { act, render, screen } from "@testing-library/react"
 import { useState } from "react"
-import { BehaviorSubject, filter, map, switchMap } from "rxjs"
+import { BehaviorSubject } from "rxjs"
 import { describe, expect, it } from "vitest"
 import {
+  createLiveQueryFn,
   createQueryClient,
   createWrapper,
-  isDefined,
   liveQueryOptions,
 } from "../../tests/liveQuery"
 import { waitForTimeout } from "../../tests/utils"
@@ -23,12 +23,7 @@ describe("useQuery$ unmount / remount", () => {
       const { data } = useQuery$({
         ...liveQueryOptions,
         queryKey: ["unmount", "add"],
-        queryFn: () =>
-          db$.pipe(
-            filter(isDefined),
-            switchMap(() => liveQuery$),
-            map((items) => [...items]),
-          ),
+        queryFn: createLiveQueryFn(db$, liveQuery$),
       })
 
       return <span data-testid="data">{JSON.stringify(data)}</span>
@@ -84,12 +79,7 @@ describe("useQuery$ unmount / remount", () => {
       const { data } = useQuery$({
         ...liveQueryOptions,
         queryKey: ["unmount", "remove"],
-        queryFn: () =>
-          db$.pipe(
-            filter(isDefined),
-            switchMap(() => liveQuery$),
-            map((items) => [...items]),
-          ),
+        queryFn: createLiveQueryFn(db$, liveQuery$),
       })
 
       return <span data-testid="data">{JSON.stringify(data)}</span>
@@ -141,12 +131,7 @@ describe("useQuery$ unmount / remount", () => {
       const { data } = useQuery$({
         ...liveQueryOptions,
         queryKey: ["unmount", "multi"],
-        queryFn: () =>
-          db$.pipe(
-            filter(isDefined),
-            switchMap(() => liveQuery$),
-            map((items) => [...items]),
-          ),
+        queryFn: createLiveQueryFn(db$, liveQuery$),
       })
 
       return <span data-testid="data">{JSON.stringify(data)}</span>
@@ -209,12 +194,7 @@ describe("useQuery$ unmount / remount", () => {
       const { data } = useQuery$({
         ...liveQueryOptions,
         queryKey: ["unmount", "stale-guard"],
-        queryFn: () =>
-          db$.pipe(
-            filter(isDefined),
-            switchMap(() => liveQuery$),
-            map((items) => [...items]),
-          ),
+        queryFn: createLiveQueryFn(db$, liveQuery$),
       })
 
       return <span data-testid="data">{JSON.stringify(data)}</span>
diff --git a/src/tests/liveQuery.tsx b/src/tests/liveQuery.tsx
index 51f5e54..a4695be 100644
--- a/src/tests/liveQuery.tsx
+++ b/src/tests/liveQuery.tsx
@@ -1,10 +1,10 @@
 import { QueryClient, QueryClientProvider } from "@tanstack/react-query"
 import type React from "react"
+import { type BehaviorSubject, filter, map, switchMap } from "rxjs"
 import { QueryClientProvider$ } from "../lib/queries/QueryClientProvider$"
+import { isDefined } from "../lib/utils/isDefined"
 
-export function isDefined<T>(value: T | undefined | null): value is T {
-  return value != null
-}
+export { isDefined }
 
 export function createQueryClient() {
   return new QueryClient({
@@ -31,3 +31,20 @@ export function createWrapper(queryClient: QueryClient) {
     )
   }
 }
+
+/**
+ * The live-query test suites all model the same shape: a `db$` gate that must
+ * be defined before the query yields, feeding a `liveQuery$` list that emits
+ * the latest items. This builds the Observable `queryFn` they share.
+ */
+export function createLiveQueryFn<T>(
+  db$: BehaviorSubject<object | undefined>,
+  liveQuery$: BehaviorSubject<T[]>,
+) {
+  return () =>
+    db$.pipe(
+      filter(isDefined),
+      switchMap(() => liveQuery$),
+      map((items) => [...items]),
+    )
+}