fix: keep promise chains intact (#4558)

Author: Uzlopak

lib/core/util.js

@@ -615,14 +615,14 @@ function ReadableStreamFrom (iterable) {
       pull (controller) {
         return iterator.next().then(({ done, value }) => {
           if (done) {
-            queueMicrotask(() => {
+            return queueMicrotask(() => {
               controller.close()
               controller.byobRequest?.respond(0)
             })
           } else {
             const buf = Buffer.isBuffer(value) ? value : Buffer.from(value)
             if (buf.byteLength) {
-              controller.enqueue(new Uint8Array(buf))
+              return controller.enqueue(new Uint8Array(buf))
             } else {
               return this.pull(controller)
             }

lib/dispatcher/dispatcher-base.js

@@ -78,9 +78,7 @@ class DispatcherBase extends Dispatcher {
     // Should not error.
     this[kClose]()
       .then(() => this.destroy())
-      .then(() => {
-        queueMicrotask(onClosed)
-      })
+      .then(() => queueMicrotask(onClosed))
   }
 
   destroy (err, callback) {
@@ -127,9 +125,8 @@ class DispatcherBase extends Dispatcher {
     }
 
     // Should not error.
-    this[kDestroy](err).then(() => {
-      queueMicrotask(onDestroyed)
-    })
+    this[kDestroy](err)
+      .then(() => queueMicrotask(onDestroyed))
   }
 
   dispatch (opts, handler) {

lib/dispatcher/pool-base.js

@@ -52,7 +52,7 @@ class PoolBase extends DispatcherBase {
       for (let i = 0; i < this[kClients].length; i++) {
         closeAll[i] = this[kClients][i].close()
       }
-      Promise.all(closeAll)
+      return Promise.all(closeAll)
         .then(this[kClosedResolve])
     }
   }

lib/interceptor/cache.js

@@ -9,6 +9,8 @@ const CacheRevalidationHandler = require('../handler/cache-revalidation-handler'
 const { assertCacheStore, assertCacheMethods, makeCacheKey, normalizeHeaders, parseCacheControlHeader } = require('../util/cache.js')
 const { AbortError } = require('../core/errors.js')
 
+const nop = () => {}
+
 /**
  * @typedef {(options: import('../../types/dispatcher.d.ts').default.DispatchOptions, handler: import('../../types/dispatcher.d.ts').default.DispatchHandler) => void} DispatchFn
  */
@@ -102,7 +104,7 @@ function handleUncachedResponse (
       }
 
       if (typeof handler.onHeaders === 'function') {
-        handler.onHeaders(504, [], () => {}, 'Gateway Timeout')
+        handler.onHeaders(504, [], nop, 'Gateway Timeout')
         if (aborted) {
           return
         }
@@ -325,7 +327,7 @@ function handleResult (
           if (success) {
             sendCachedValue(handler, opts, result, age, context, true)
           } else if (util.isStream(result.body)) {
-            result.body.on('error', () => {}).destroy()
+            result.body.on('error', nop).destroy()
           }
         },
         new CacheHandler(globalOpts, cacheKey, handler),
@@ -336,7 +338,7 @@ function handleResult (
 
   // Dump request body.
   if (util.isStream(opts.body)) {
-    opts.body.on('error', () => {}).destroy()
+    opts.body.on('error', nop).destroy()
   }
 
   sendCachedValue(handler, opts, result, age, null, false)
@@ -405,18 +407,17 @@ module.exports = (opts = {}) => {
       const result = store.get(cacheKey)
 
       if (result && typeof result.then === 'function') {
-        result.then(result => {
-          handleResult(dispatch,
+        return result
+          .then(result => handleResult(dispatch,
             globalOpts,
             cacheKey,
             handler,
             opts,
             reqCacheControl,
             result
-          )
-        })
+          ))
       } else {
-        handleResult(
+        return handleResult(
           dispatch,
           globalOpts,
           cacheKey,
@@ -426,8 +427,6 @@ module.exports = (opts = {}) => {
           result
         )
       }
-
-      return true
     }
   }
 }

lib/mock/mock-utils.js

@@ -337,8 +337,7 @@ function mockDispatch (opts, handler) {
       // synchronously throw the error, which breaks some tests.
       // Rather, we wait for the callback to resolve if it is a
       // promise, and then re-run handleReply with the new body.
-      body.then((newData) => handleReply(mockDispatches, newData))
-      return
+      return body.then((newData) => handleReply(mockDispatches, newData))
     }
 
     const responseData = getResponseData(body)

lib/mock/snapshot-agent.js

@@ -162,11 +162,9 @@ class SnapshotAgent extends MockAgent {
           headers: responseData.headers,
           body: responseBody,
           trailers: responseData.trailers
-        }).then(() => {
-          handler.onResponseEnd(controller, trailers)
-        }).catch((error) => {
-          handler.onResponseError(controller, error)
         })
+          .then(() => handler.onResponseEnd(controller, trailers))
+          .catch((error) => handler.onResponseError(controller, error))
       }
     }