# Changelog — 2026-03-31 #02

## Comprehensive test suite and bug fixes

### Tests Added

- **structs_spec.rb**: Added struct equality tests (same values equal, different values not equal)
- **errors_spec.rb**: Added StandardError inheritance test, rescue-as-StandardError test, RateLimitError retry_after default, rescue-as-Error test
- **copilot_spec.rb**: Added tests for:
  - VERSION constant accessibility
  - Multiple tool calls in a single response
  - Empty tools array omits `tools` key from request body
  - TextBlock array in user messages converted to string content
  - ToolResultBlock with array content (Array of TextBlocks)
  - ToolResultBlock with is_error: true
  - finish_reason "length" maps to :max_tokens stop_reason
  - Assistant message containing mixed text + tool_use blocks
  - Streaming usage data capture
  - Multiple parallel tool calls in streaming
  - Copilot token caching (reuses token, only 1 token request for 2 chats)
  - Authentication failure on Copilot token exchange

### Bug Fixes

- **copilot.rb**: Fixed `Array(hash)` bug in `build_wire_messages` — `Array()` on a Hash converts it to key-value pairs instead of wrapping in an array. Replaced with explicit `is_a?(Array)` check.
- **copilot.rb**: Fixed empty argument fragment yielding in streaming — empty string arguments from initial tool_call chunks were being yielded as `tool_use_delta` events. Added `next if arg_frag.empty?` guard.

### Total Test Count

84 examples, 0 failures across 4 spec files.