Design a Comprehensive Test Plan and TDD Workflow for Word-Search Functions

Context and Assumptions

We are testing two grid-based word search functions that operate on a 2D character grid. To make the task self-contained, assume the following interfaces and semantics:

• Function A: existsFixedDirection(grid, word) -> bool
  • Returns true if the word appears contiguously in a straight line along any of the 8 compass directions (N, NE, E, SE, S, SW, W, NW) without wrapping and without reusing cells beyond the contiguous straight-line traversal.
• Function B: existsPathAnyDirection(grid, word) -> bool (or -> path if your design returns coordinates)
  • Returns true if there exists a path spelling the word by moving step-by-step to any of the 8 neighboring cells per letter. Direction can change between steps. A cell cannot be reused within the same word instance (no revisits in one path). No wrapping beyond edges.
• Inputs:
  • grid: non-jagged 2D array/list of single-character strings.
  • word: string (possibly empty or with repeated letters); normalization rules to be specified.

Task

Design a thorough test plan and a test-driven development workflow for both functions. Enumerate concrete test cases covering:

• Empty grid
• Empty word
• Single-letter grid/word matches and mismatches
• Straight-line matches in all eight directions
• Attempts requiring direction changes (should fail under fixed-direction)
• Diagonal-only matches
• Boundary-crossing attempts
• Words with repeated letters that tempt revisits
• Multiple valid starting positions
• Grids with no occurrence
• Large inputs for performance and stack-depth concerns
• Invalid/normalization inputs (if applicable)

Describe how you would structure unit, property-based, and stress tests, and define pass/fail criteria.