(fix): timeouts for sync handlers returning non-undefined values; fix ESM return values (#665)

nhulston · web-flow · commit ef07049f3823 · 2025-07-07T11:01:48.000-04:00
* fix: handle sync handlers returning values to prevent timeout issues

* fix: sync handlers with callbacks

* unit tests

* update snapshots
diff --git a/integration_tests/snapshots/logs/esm_node18.log b/integration_tests/snapshots/logs/esm_node18.log
diff --git a/integration_tests/snapshots/logs/esm_node20.log b/integration_tests/snapshots/logs/esm_node20.log
diff --git a/integration_tests/snapshots/logs/esm_node22.log b/integration_tests/snapshots/logs/esm_node22.log
diff --git a/integration_tests/snapshots/return_values/esm_node18_api-gateway-get.json b/integration_tests/snapshots/return_values/esm_node18_api-gateway-get.json
@@ -1 +1,3 @@
-null
+{
+    "message": "hello, dog!"
+}
diff --git a/integration_tests/snapshots/return_values/esm_node18_dynamodb-one-key-table.json b/integration_tests/snapshots/return_values/esm_node18_dynamodb-one-key-table.json
@@ -1 +1,3 @@
-null
+{
+    "message": "hello, dog!"
+}
diff --git a/integration_tests/snapshots/return_values/esm_node18_dynamodb-remove.json b/integration_tests/snapshots/return_values/esm_node18_dynamodb-remove.json
@@ -1 +1,3 @@
-null
+{
+    "message": "hello, dog!"
+}
diff --git a/integration_tests/snapshots/return_values/esm_node18_dynamodb-two-key-table.json b/integration_tests/snapshots/return_values/esm_node18_dynamodb-two-key-table.json
@@ -1 +1,3 @@
-null
+{
+    "message": "hello, dog!"
+}
diff --git a/integration_tests/snapshots/return_values/esm_node18_s3-completemultipartupload.json b/integration_tests/snapshots/return_values/esm_node18_s3-completemultipartupload.json
@@ -1 +1,3 @@
-null
+{
+    "message": "hello, dog!"
+}
diff --git a/integration_tests/snapshots/return_values/esm_node18_s3-copyobject.json b/integration_tests/snapshots/return_values/esm_node18_s3-copyobject.json
@@ -1 +1,3 @@
-null
+{
+    "message": "hello, dog!"
+}
diff --git a/integration_tests/snapshots/return_values/esm_node18_s3-putobject.json b/integration_tests/snapshots/return_values/esm_node18_s3-putobject.json
@@ -1 +1,3 @@
-null
+{
+    "message": "hello, dog!"
+}
diff --git a/integration_tests/snapshots/return_values/esm_node18_sns.json b/integration_tests/snapshots/return_values/esm_node18_sns.json
@@ -1 +1,3 @@
-null
+{
+    "message": "hello, dog!"
+}
diff --git a/integration_tests/snapshots/return_values/esm_node18_sqs.json b/integration_tests/snapshots/return_values/esm_node18_sqs.json
@@ -1 +1,3 @@
-null
+{
+    "message": "hello, dog!"
+}
diff --git a/integration_tests/snapshots/return_values/esm_node20_api-gateway-get.json b/integration_tests/snapshots/return_values/esm_node20_api-gateway-get.json
@@ -1 +1,3 @@
-null
+{
+    "message": "hello, dog!"
+}
diff --git a/integration_tests/snapshots/return_values/esm_node20_dynamodb-one-key-table.json b/integration_tests/snapshots/return_values/esm_node20_dynamodb-one-key-table.json
@@ -1 +1,3 @@
-null
+{
+    "message": "hello, dog!"
+}
diff --git a/integration_tests/snapshots/return_values/esm_node20_dynamodb-remove.json b/integration_tests/snapshots/return_values/esm_node20_dynamodb-remove.json
@@ -1 +1,3 @@
-null
+{
+    "message": "hello, dog!"
+}
diff --git a/integration_tests/snapshots/return_values/esm_node20_dynamodb-two-key-table.json b/integration_tests/snapshots/return_values/esm_node20_dynamodb-two-key-table.json
@@ -1 +1,3 @@
-null
+{
+    "message": "hello, dog!"
+}
diff --git a/integration_tests/snapshots/return_values/esm_node20_s3-completemultipartupload.json b/integration_tests/snapshots/return_values/esm_node20_s3-completemultipartupload.json
@@ -1 +1,3 @@
-null
+{
+    "message": "hello, dog!"
+}
diff --git a/integration_tests/snapshots/return_values/esm_node20_s3-copyobject.json b/integration_tests/snapshots/return_values/esm_node20_s3-copyobject.json
@@ -1 +1,3 @@
-null
+{
+    "message": "hello, dog!"
+}
diff --git a/integration_tests/snapshots/return_values/esm_node20_s3-putobject.json b/integration_tests/snapshots/return_values/esm_node20_s3-putobject.json
@@ -1 +1,3 @@
-null
+{
+    "message": "hello, dog!"
+}
diff --git a/integration_tests/snapshots/return_values/esm_node20_sns.json b/integration_tests/snapshots/return_values/esm_node20_sns.json
@@ -1 +1,3 @@
-null
+{
+    "message": "hello, dog!"
+}
diff --git a/integration_tests/snapshots/return_values/esm_node20_sqs.json b/integration_tests/snapshots/return_values/esm_node20_sqs.json
@@ -1 +1,3 @@
-null
+{
+    "message": "hello, dog!"
+}
diff --git a/integration_tests/snapshots/return_values/esm_node22_api-gateway-get.json b/integration_tests/snapshots/return_values/esm_node22_api-gateway-get.json
@@ -1 +1,3 @@
-null
+{
+    "message": "hello, dog!"
+}
diff --git a/integration_tests/snapshots/return_values/esm_node22_dynamodb-one-key-table.json b/integration_tests/snapshots/return_values/esm_node22_dynamodb-one-key-table.json
@@ -1 +1,3 @@
-null
+{
+    "message": "hello, dog!"
+}
diff --git a/integration_tests/snapshots/return_values/esm_node22_dynamodb-remove.json b/integration_tests/snapshots/return_values/esm_node22_dynamodb-remove.json
@@ -1 +1,3 @@
-null
+{
+    "message": "hello, dog!"
+}
diff --git a/integration_tests/snapshots/return_values/esm_node22_dynamodb-two-key-table.json b/integration_tests/snapshots/return_values/esm_node22_dynamodb-two-key-table.json
@@ -1 +1,3 @@
-null
+{
+    "message": "hello, dog!"
+}
diff --git a/integration_tests/snapshots/return_values/esm_node22_s3-completemultipartupload.json b/integration_tests/snapshots/return_values/esm_node22_s3-completemultipartupload.json
@@ -1 +1,3 @@
-null
+{
+    "message": "hello, dog!"
+}
diff --git a/integration_tests/snapshots/return_values/esm_node22_s3-copyobject.json b/integration_tests/snapshots/return_values/esm_node22_s3-copyobject.json
@@ -1 +1,3 @@
-null
+{
+    "message": "hello, dog!"
+}
diff --git a/integration_tests/snapshots/return_values/esm_node22_s3-putobject.json b/integration_tests/snapshots/return_values/esm_node22_s3-putobject.json
@@ -1 +1,3 @@
-null
+{
+    "message": "hello, dog!"
+}
diff --git a/integration_tests/snapshots/return_values/esm_node22_sns.json b/integration_tests/snapshots/return_values/esm_node22_sns.json
@@ -1 +1,3 @@
-null
+{
+    "message": "hello, dog!"
+}
diff --git a/integration_tests/snapshots/return_values/esm_node22_sqs.json b/integration_tests/snapshots/return_values/esm_node22_sqs.json
@@ -1 +1,3 @@
-null
+{
+    "message": "hello, dog!"
+}
diff --git a/src/utils/handler.spec.ts b/src/utils/handler.spec.ts
@@ -325,4 +325,34 @@ describe("wrap", () => {
     expect(calledComplete).toBeTruthy();
     expect(calledOriginalHandler).toBeFalsy();
   });
+
+  it("completes when handler returns a value directly (sync handler)", async () => {
+    const handler = (event: any, context: Context) => {
+      // Return a value directly without using callback or promise
+      return { statusCode: 200, body: "Sync response" };
+    };
+
+    let calledStart = false;
+    let calledComplete = false;
+    let calledOriginalHandler = false;
+
+    const wrappedHandler = wrap(
+      handler as any,
+      async () => {
+        calledStart = true;
+      },
+      async () => {
+        calledComplete = true;
+      },
+    );
+
+    const result = await wrappedHandler({}, mockContext, () => {
+      calledOriginalHandler = true;
+    });
+
+    expect(result).toEqual({ statusCode: 200, body: "Sync response" });
+    expect(calledStart).toBeTruthy();
+    expect(calledComplete).toBeTruthy();
+    expect(calledOriginalHandler).toBeFalsy();
+  });
 });
diff --git a/src/utils/handler.ts b/src/utils/handler.ts
@@ -124,6 +124,12 @@ export function promisifiedHandler<TEvent, TResult>(handler: Handler<TEvent, TRe
     } else if (asyncProm === undefined && handler.length < 3) {
       // Handler returned undefined and doesn't take a callback parameter, resolve immediately
       promise = Promise.resolve(undefined);
+    } else if (handler.length >= 3) {
+      // Handler takes a callback, wait for the callback to be called
+      promise = callbackProm;
+    } else {
+      // Handler returned a value directly (sync handler with return value), resolve with that value
+      promise = Promise.resolve(asyncProm);
     }
     return promise;
   };

-Original file line number
+Diff line change
@@ @@ -1 +1,3 @@ @@
 -null
 +{
 +    "message": "hello, dog!"
 +}