style(batch): apply stricter linting

packages/batch/src/BasePartialProcessor.ts

@@ -239,9 +239,7 @@ abstract class BasePartialProcessor {
   /**
    * Processes records in parallel using `Promise.all`.
    */
-  async #processRecordsInParallel(): Promise<
-    (SuccessResponse | FailureResponse)[]
-  > {
+  #processRecordsInParallel(): Promise<(SuccessResponse | FailureResponse)[]> {
     return Promise.all(
       this.records.map((record) => this.processRecord(record))
     );

packages/batch/src/BatchProcessorSync.ts

@@ -88,7 +88,7 @@ import type { BaseRecord, FailureResponse, SuccessResponse } from './types.js';
    *
    * @param _record The record to be processed
    */
-  public async processRecord(
+  public processRecord(
     _record: BaseRecord
   ): Promise<SuccessResponse | FailureResponse> {
     throw new BatchProcessingError('Not implemented. Use process() instead.');

packages/batch/tests/helpers/handlers.ts

@@ -1,4 +1,6 @@
+import { setTimeout } from 'node:timers/promises';
 import type {
+  AttributeValue,
   Context,
   DynamoDBRecord,
   KinesisStreamRecord,
@@ -8,50 +10,70 @@ import type {
 const sqsRecordHandler = (record: SQSRecord): string => {
   const body = record.body;
   if (body.includes('fail')) {
-    throw Error('Failed to process record.');
+    throw new Error('Failed to process record.');
   }
 
   return body;
 };
 
-const asyncSqsRecordHandler = async (record: SQSRecord): Promise<string> =>
-  Promise.resolve(sqsRecordHandler(record));
+const asyncSqsRecordHandler = async (record: SQSRecord): Promise<string> => {
+  const body = record.body;
+  if (body.includes('fail')) {
+    throw new Error('Failed to process record.');
+  }
+  await setTimeout(1); // simulate some processing time
+  return body;
+};
 
 const kinesisRecordHandler = (record: KinesisStreamRecord): string => {
   const body = record.kinesis.data;
   if (body.includes('fail')) {
-    throw Error('Failed to process record.');
+    throw new Error('Failed to process record.');
   }
 
   return body;
 };
 
 const asyncKinesisRecordHandler = async (
   record: KinesisStreamRecord
-): Promise<string> => Promise.resolve(kinesisRecordHandler(record));
+): Promise<string> => {
+  const body = record.kinesis.data;
+  if (body.includes('fail')) {
+    throw new Error('Failed to process record.');
+  }
+  await setTimeout(1); // simulate some processing time
+  return body;
+};
 
-const dynamodbRecordHandler = (record: DynamoDBRecord): object => {
+const dynamodbRecordHandler = (record: DynamoDBRecord): AttributeValue => {
   const body = record.dynamodb?.NewImage?.Message || { S: 'fail' };
   if (body.S?.includes('fail')) {
-    throw Error('Failed to process record.');
+    throw new Error('Failed to process record.');
   }
 
   return body;
 };
 
 const asyncDynamodbRecordHandler = async (
   record: DynamoDBRecord
-): Promise<object> => {
-  return Promise.resolve(dynamodbRecordHandler(record));
+): Promise<AttributeValue> => {
+  const body = record.dynamodb?.NewImage?.Message || { S: 'fail' };
+  if (body.S?.includes('fail')) {
+    throw new Error('Failed to process record.');
+  }
+  await setTimeout(1); // simulate some processing time
+  return body;
 };
 
 const handlerWithContext = (record: SQSRecord, context: Context): string => {
   try {
     if (context.getRemainingTimeInMillis() === 0) {
-      throw Error('No time remaining.');
+      throw new Error('No time remaining.');
     }
   } catch {
-    throw Error(`Context possibly malformed. Displaying context:\n${context}`);
+    throw new Error(
+      `Context possibly malformed. Displaying context:\n${context}`
+    );
   }
 
   return record.body;
@@ -61,7 +83,17 @@ const asyncHandlerWithContext = async (
   record: SQSRecord,
   context: Context
 ): Promise<string> => {
-  return Promise.resolve(handlerWithContext(record, context));
+  try {
+    if (context.getRemainingTimeInMillis() === 0) {
+      throw new Error('No time remaining.');
+    }
+  } catch {
+    throw new Error(
+      `Context possibly malformed. Displaying context:\n${context}`
+    );
+  }
+  await setTimeout(1); // simulate some processing time
+  return record.body;
 };
 
 export {

packages/batch/tests/unit/BasePartialProcessor.test.ts

@@ -25,7 +25,7 @@ describe('Class: BasePartialBatchProcessor', () => {
       super(EventType.SQS);
     }
 
-    public async processRecord(
+    public processRecord(
       _record: BaseRecord
     ): Promise<SuccessResponse | FailureResponse> {
       throw new Error('Not implemented');

packages/batch/tests/unit/SqsFifoPartialProcessor.test.ts

@@ -186,7 +186,7 @@ describe('SQS FIFO Processors', () => {
     });
   }
 
-  it('continues processing and moves to the next group when `skipGroupOnError` is true', async () => {
+  it('continues processing and moves to the next group when `skipGroupOnError` is true', () => {
     // Prepare
     const firstRecord = sqsRecordFactory('fail', '1');
     const secondRecord = sqsRecordFactory('success', '2');

packages/batch/tests/unit/processPartialResponse.test.ts

@@ -36,10 +36,10 @@ describe('Function: processPartialResponse()', () => {
     context,
   };
 
-  const handlerWithSqsEvent = async (
+  const handlerWithSqsEvent = (
     event: SQSEvent,
     options: BatchProcessingOptions
-  ) => {
+  ): Promise<PartialItemFailureResponse> => {
     const processor = new BatchProcessor(EventType.SQS);
 
     const handler = async (
@@ -51,10 +51,10 @@ describe('Function: processPartialResponse()', () => {
     return handler(event, context);
   };
 
-  const handlerWithKinesisEvent = async (
+  const handlerWithKinesisEvent = (
     event: KinesisStreamEvent,
     options: BatchProcessingOptions
-  ) => {
+  ): Promise<PartialItemFailureResponse> => {
     const processor = new BatchProcessor(EventType.KinesisDataStreams);
 
     const handler = async (
@@ -71,10 +71,10 @@ describe('Function: processPartialResponse()', () => {
     return handler(event, context);
   };
 
-  const handlerWithDynamoDBEvent = async (
+  const handlerWithDynamoDBEvent = (
     event: DynamoDBStreamEvent,
     options: BatchProcessingOptions
-  ) => {
+  ): Promise<PartialItemFailureResponse> => {
     const processor = new BatchProcessor(EventType.DynamoDBStreams);
 
     const handler = async (