Mouse-Maze Controller: Design a Comprehensive Unit Test Suite

Context (assumptions to make the task self-contained)

Assume we are testing a controller that navigates a grid-based maze to find cheese. The controller drives an abstract Maze API and must return the first cheese it finds according to a deterministic neighbor-order policy. Multiple cheeses may exist; some may be unreachable.

• Grid representation: rectangular grid with walls and open cells.
• Start position: a single cell where the mouse begins.
• Cheese: one or more target cells; reaching any one ends the search successfully.
• Deterministic neighbor exploration order: Up, Right, Down, Left (URDL), unless otherwise specified.
• The Maze API can signal walls/valid moves and may throw errors on move attempts.
• Controller output: either a path (sequence of directions) to a found cheese, or a NotFound/Failure result.

You may minimally adjust the exact API shape but keep behavior semantically equivalent to the above.

Task

Propose a comprehensive set of unit tests for the mouse-maze controller. Include tests for:

1. Single-cell maze
2. Unreachable cheese
3. Narrow corridors and cul-de-sacs
4. Loops/cycles
5. Large open spaces
6. Obstacle directly ahead
7. Repeated visits and backtracking correctness
8. Multiple cheeses (ensure the first found is returned)
9. Performance and stack-depth limits
10. API error behavior (e.g., move() throwing)

Also describe how to stub/simulate the Maze API deterministically to support these tests.