Feature/s3 unit tests

[Sujeev-Uthayakumar]

📌 Description

Implemented tests for the s3.go file, using unit tests mock as defined by the AWS documentation: https://docs.aws.amazon.com/sdk-for-go/v2/developer-guide/unit-testing.html. This methodology decouples the dependency on the AWS api, allowing you to interchange dependencies for mocking.

• Closes [TASK] Add Unit Tests for S3BlobStorage #212

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🔍 Changes Made

• Added a new S3Api interface to allow for mocking the S3Client in the s3.go file
• Implemented S3Client mocking inside the s3_blob_storage_test.go file
• Wrote tests for NewS3BlobStorage, IsEnabled, Store, Retrieve, Delete, Exists.
• Added helper functions to provide simple test utilities.

✅ Checklist (Email System)

• Core IMAP commands tested (LOGIN, CAPABILITY, LIST, SELECT, FETCH, LOGOUT).
• Authentication is tested.
• Docker build & run validated.
• Configuration loading verified for default and custom paths.
• Persistent storage with Docker volume verified.
• Error handling and logging verified
• Documentation updated (README, config samples).

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🧪 Testing Instructions

To test the server, use the instructions in the README in the test directory.

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📷 Screenshots / Logs (if applicable)

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⚠️ Notes for Reviewers

[CLAassistant]

All committers have signed the CLA.

[gemini-code-assist]

Summary of Changes

Hello @Sujeev-Uthayakumar, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly enhances the testability and reliability of the S3 blob storage module by introducing a mocking strategy for the AWS S3 client. This approach allows for isolated and efficient unit testing of the storage operations, ensuring their correctness and robustness without relying on external AWS services.

Highlights

• S3 API Interface: A new "S3Api" interface has been introduced in "s3.go" to abstract S3 operations, enabling easier mocking for testing.
• S3 Client Mocking: A "mockS3Client" implementation has been added in "s3_blob_storage_test.go" to simulate S3 service behavior without actual AWS API calls.
• Comprehensive Unit Tests: Unit tests have been written for all key "S3BlobStorage" methods, including "NewS3BlobStorage", "IsEnabled", "Store", "Retrieve", "Delete", and "Exists", covering various scenarios like success, failure, and edge cases.
• Test Utilities: Several helper functions ("newMockS3BlobStorage", "contains", "bytesContains", "bytesEqual", "errorReader") were added to facilitate robust and clear testing.

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[gemini-code-assist]

Code Review

This pull request introduces unit tests for the S3 blob storage functionality, which is a great step towards improving code quality and reliability. The introduction of the S3Api interface to enable mocking is an excellent application of dependency injection. My review focuses on improving the test accuracy, robustness of the error handling in the underlying implementation that the new tests cover, and general code hygiene in the test file. I've identified a few areas for improvement: a logic bug in the test setup, incomplete error handling in the Store and Exists methods that the new tests should catch, and replacement of custom helper functions with standard library equivalents.

[Aravinda-HWK]

I went through the PR, and the implementation of the unit test cases for the blob storage follows best practices for testing SDK-based integrations.

Thank you for your interest in our project and for the contribution. Please keep an eye on the repository, we’ll continue to update the Issues section with good first issues for future contributions.