Added support for string-content attachments & fixed HTTParty encoding issues. (#530)

* fix(http-client): replace Tempfile with StringIO for multipart uploads

- Replace Tempfile with StringIO in prepare_multipart_payload to eliminate filesystem dependencies
- Add enhanced StringIO compatibility methods for HTTParty multipart handling
- Update test expectations from Tempfile to StringIO
- Add defensive file closing in messages.rb
- Resolves issues with read-only containers and AWS Lambda environments

Fixes #528

* fix(http-client): resolve HTTParty encoding compatibility issue with multipart requests

Fixes #528

- Resolves 'incompatible character encodings: ASCII-8BIT and UTF-8' error when sending multipart requests
- Normalizes all multipart payload strings to consistent ASCII-8BIT encoding for HTTParty compatibility
- Maintains backward compatibility while preventing encoding conflicts during multipart body generation
- Updates test expectations to reflect new encoding behavior

* Fix UTF-8 encoding issue with binary attachment content in JSON serialization

- Add normalize_json_encodings! method to handle binary attachment content
- Automatically base64 encode binary strings before JSON serialization
- Fixes 'source sequence is illegal/malformed utf-8' error when sending
  attachments with raw binary content via JSON (non-multipart) requests
- Preserves backward compatibility with both symbol and string keys
- Resolves issue #528

Author: AaronDDM

.gitignore

@@ -2,6 +2,9 @@
 **/*/.env
 # Example test files
 examples/messages/large_test_file.txt
+examples/messages/small_pdf_test_file.pdf
+examples/messages/large_pdf_test_file.pdf
+examples/messages/large_jpg_test_file.jpg
 *.gem
 *.rbc
 .bundle

CHANGELOG.md

@@ -3,6 +3,8 @@
 ### [Unreleased]
 * Added support for `single_level` query parameter in Folders API for Microsoft accounts
 * Added support for `include_hidden_folders` query parameter in folders list endpoint for Microsoft accounts to control whether hidden folders are included in the response
+* Added support for passing in string contents for multipart and base64 (<3MB) attachments (#528) 
+* Fixed HTTParty encoding compatibility issue with multipart requests (#528)
 
 ### 6.5.0 / 2025-06-13
 * Replaced `rest-client` dependency with `httparty` for improved maintainability and security