Add test suite for snippet.lua module

Overview

The snippet.lua module (~47 lines) handles snippet insertion with variable expansion. No tests currently exist.

Functions Needing Tests

Public Functions

• insert_snippet() - Main entry point
  • Test: displays snippet picker
  • Test: handles snippet selection
  • Test: handles no snippets found
  • Test: handles .zk directory not found
  • Test: handles user cancellation

Internal Functions

• insert_snippet(zk_dir, notebook_dir, snippet_name) - Insert snippet with expansion
  • Test: reads snippet file correctly
  • Test: expands template variables
  • Test: inserts at cursor position
  • Test: handles multi-line snippets
  • Test: handles snippet file not found
  • Test: handles file read errors
  • Test: preserves cursor position after insertion

Integration Tests

• Test: snippet with {{date}} variable
• Test: snippet with {{input:prompt}} variable
• Test: snippet with {{clipboard}} variable
• Test: snippet with custom variables
• Test: snippet insertion doesn't affect other buffer content
• Test: undo works correctly after snippet insertion

Edge Cases

• Empty snippet file
• Snippet with no variables
• Very large snippet file
• Binary file instead of text
• Unicode content in snippet

Test File Location

tests/zk-extras/snippet_spec.lua

Priority

Medium - Important feature but smaller module