Refactored integration test infrastructure

#391 in iced-rs/iced_aw — merged 2025-12-31

Refactored integration test infrastructure to eliminate code duplication

Summary of Key Changes

• Created tests/common/mod.rs with test_helpers! macro to generate type-safe test utilities
• Refactored integration test files to use common helpers
• Added testing guide in tests/README.md

Impact

• Reduced test boilerplate by about 25%. Future test files can reuse the macro for consistent testing patterns.

cargo test --lib --bins --tests