Make keepAlive an option, add a log when quiet:false

Author: msutkowski

src/mockServiceWorker.js

@@ -27,9 +27,9 @@ self.addEventListener('message', async function (event) {
   const allClientIds = allClients.map((client) => client.id)
 
   switch (event.data) {
-    case 'PING': {
+    case 'KEEPALIVE_REQUEST': {
       sendToClient(client, {
-        type: 'PONG',
+        type: 'KEEPALIVE_RESPONSE',
         payload: new Date(),
       })
       break

src/setupWorker/glossary.ts

@@ -11,7 +11,7 @@ export interface SetupWorkerInternalContext {
   worker: ServiceWorker | null
   registration: ServiceWorkerRegistration | null
   requestHandlers: RequestHandler<any, any>[]
-  keepAliveInterval?: ReturnType<typeof setInterval> | number
+  keepAliveInterval?: number
   events: {
     /**
      * Adds an event listener on the given target.
@@ -66,6 +66,12 @@ export type StartOptions = SharedOptions & {
    * of all registered Service Workers on the page.
    */
   findWorker?: FindWorker
+
+  /**
+   * Disable the keep alive or use a custom interval.
+   * Defaults to 10000 (ms)
+   */
+  keepAlive?: false | number
 }
 
 export type RequestHandlersList = RequestHandler<any, any>[]

src/setupWorker/start/createStart.ts

@@ -17,6 +17,7 @@ const DEFAULT_START_OPTIONS: DeepRequired<StartOptions> = {
     options: null as any,
   },
   quiet: false,
+  keepAlive: 10000,
   waitUntilReady: true,
   onUnhandledRequest: 'bypass',
   findWorker: (scriptURL, mockServiceWorkerUrl) =>
@@ -94,6 +95,9 @@ Please consider using a custom "serviceWorker.url" option to point to the actual
           // the Service Worker when there are no open clients.
           worker.postMessage('CLIENT_CLOSED')
         }
+        // Make sure we're always clearing the interval - there are reports that not doing this can
+        // cause memory leaks in headless browser environments.
+        window.clearInterval(context.keepAliveInterval)
       })
 
       // Check if the active Service Worker is the latest published one
@@ -124,10 +128,12 @@ If this message still persists after updating, please report an issue: https://g
         return null
       }
 
-      context.keepAliveInterval = setInterval(
-        () => worker.postMessage('PING'),
-        5000,
-      )
+      if (resolvedOptions.keepAlive) {
+        context.keepAliveInterval = window.setInterval(
+          () => worker.postMessage('KEEPALIVE_REQUEST'),
+          resolvedOptions.keepAlive,
+        )
+      }
 
       return registration
     }

src/setupWorker/stop/createStop.ts

@@ -9,6 +9,6 @@ export const createStop = (context: SetupWorkerInternalContext) => {
   return function stop() {
     context.worker?.postMessage('MOCK_DEACTIVATE')
     context.events.removeAllListeners()
-    clearInterval(context.keepAliveInterval as any)
+    window.clearInterval(context.keepAliveInterval)
   }
 }

src/utils/handleRequestWith.ts

@@ -57,6 +57,12 @@ export const handleRequestWith = (
 
       // Ignore irrelevant worker message types
       if (type !== 'REQUEST') {
+        if (type === 'KEEPALIVE_RESPONSE' && !options.quiet) {
+          console.info(
+            `[MSW] Received Keep Alive response from the mockServiceWorker`,
+          )
+        }
+
         return null
       }