Maintenance: Fix object stringification and test loop issues in kafka package

[dreamorosi]

Summary

The packages/kafka package contains 4 code quality issues identified by SonarQube that affect debugging experience and test reliability:

1. Object Stringification Issues (2 MINOR issues): messageType objects in error messages will display [object Object] instead of meaningful content

   • packages/kafka/src/deserializer/protobuf.ts (lines 43, 67)

2. Invalid Test Loop Logic (2 MAJOR issues): Test loops that only execute one iteration due to early returns

   • packages/kafka/tests/unit/consumer.test.ts (lines 144-150, 244-251)

These issues impact error message clarity and test reliability in the Kafka consumer functionality.

Why is this needed?

1. Better Debugging Experience: Proper object stringification provides meaningful error messages instead of [object Object]
2. SonarQube Compliance: Resolves 4 code quality issues (typescript:S6551, typescript:S1751)
3. Test Reliability: Ensures test loops execute as intended and test the correct behavior
4. Code Clarity: Makes test logic more explicit and easier to understand
5. Maintainability: Improves long-term code quality and developer experience

Solution

Important

The following changes are included as reference to help you understand the refactoring. Before implementing, please make sure to check the codebase and ensure that they make sense and they are exhaustive.

1. Fix Object Stringification in protobuf.ts (2 issues)

Current code (line 43):

throw new KafkaConsumerDeserializationError(
  `Failed to deserialize Protobuf message: ${error}, message: ${data}, messageType: ${messageType}`
);

Current code (line 67):

throw new KafkaConsumerDeserializationError(
  `Failed to deserialize Protobuf message: ${error}, message: ${data}, messageType: ${messageType}`
);

Improved code:

// Use JSON.stringify for better object representation
throw new KafkaConsumerDeserializationError(
  `Failed to deserialize Protobuf message: ${error}, message: ${data}, messageType: ${JSON.stringify(messageType)}`
);

2. Fix Test Loop Logic in consumer.test.ts (2 issues)

Current code (lines 144-150):

async (event) => {
  for (const record of event.records) {
    try {
      return record.value; // This causes the loop to exit after first iteration
    } catch (error) {
      return error;
    }
  }
}

Current code (lines 244-251):

async (event) => {
  for (const record of event.records) {
    try {
      const { value, key } = record;
      return [value, key]; // This causes the loop to exit after first iteration
    } catch (error) {
      return error;
    }
  }
}

Improved code:

// process all records, collect results
async (event) => {
  const results = [];
  for (const record of event.records) {
    try {
      results.push(record.value);
    } catch (error) {
      results.push(error);
    }
  }
  return results;
}

These changes:

• Provide meaningful error messages with proper object representation
• Fix test logic to match the intended behavior
• Improve debugging experience for developers
• Ensure tests actually test what they're supposed to test

Implementation Details

1. Files to modify:

   • packages/kafka/src/deserializer/protobuf.ts (lines 43, 67)
   • packages/kafka/tests/unit/consumer.test.ts (lines 144-150, 244-251)

2. Testing:

   • Ensure all existing tests continue to pass
   • Verify that error messages now show meaningful object information
   • Confirm that test loops behave as intended
   • Run type checking to verify no TypeScript errors are introduced

3. Validation:

   • Run npm run test:unit -w packages/kafka to ensure no regressions
   • Run npm run lint -w packages/kafka to verify code style compliance
   • Run npm run build -ws to verify TypeScript compilation
   • Run SonarQube analysis to confirm issues are resolved
   • Test error scenarios to verify improved error messages

Additional Context

This issue was identified as part of a SonarQube code quality review. The Kafka package is essential for processing Kafka events in AWS Lambda functions, making code quality improvements here particularly valuable for debugging and reliability.

The object stringification fixes will significantly improve the debugging experience when Protobuf deserialization fails, while the test loop fixes ensure that tests accurately reflect the intended behavior.

SonarQube Issue Keys:

• AZf420AbavFQG5gpn4yg - protobuf.ts line 43 object stringification
• AZf420AbavFQG5gpn4yh - protobuf.ts line 67 object stringification
• AZhgV3Vsuzyb-Brr5pXz - consumer.test.ts lines 144-150 invalid loop
• AZhgV3Vsuzyb-Brr5pX0 - consumer.test.ts lines 244-251 invalid loop

Acknowledgment

• This request meets Powertools for AWS Lambda (TypeScript) Tenets
• Should this be considered in other Powertools for AWS Lambda languages? i.e. Python, Java, and .NET

Future readers

Please react with 👍 and your use case to help us understand customer demand.

[dreamorosi]

Taking this since it's making our CI fail and reporting SonarCloud as failed when merging to main.

[powertools-for-aws-oss-automation]

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