fix: Fixed default charset behavior for various non-text/plain content types

[dazuma]

No description provided.

[Copilot]

Pull request overview

This pull request fixes the default charset behavior for various content types. Previously, us-ascii was the default charset for all content types without an explicit charset parameter. The fix introduces smarter defaults: text/plain defaults to us-ascii, text-based and JSON-based content types default to utf-8, and binary content types (like images) have no default charset.

Changes:

• Updated ContentType class to intelligently select default charsets based on media type and subtype
• Modified test fixtures to reflect the new behavior with proper JSON objects containing UTF-8 characters
• Added comprehensive test coverage for the new charset defaulting logic

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
lib/cloud_events/content_type.rb	Implements intelligent charset selection logic via choose_default_charset method; changes initialization to set all instance variables to nil initially and apply defaults in ensure block
test/test_content_type.rb	Adds test cases for different content types and their expected charset defaults (text/plain → us-ascii, application/json → utf-8, text/html → utf-8, image/png → nil)
test/test_http_binding.rb	Updates test fixtures: changes JSON test data from simple string to object with UTF-8 characters, removes charset from JSON content type string, converts all let : syntax to let(:) for consistency

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.