[23/N] Add unit tests for algo util helpers (PriorityQueue, SkipListHeads, GraphValues)

[karkir0003]

🥞 Stack

1. ⬅️ [1/N] Update CI to run frontend unit tests #91 (Update CI to run frontend unit tests)
2. ⬅️ [2/N] Configure React Testing Library and Setup Tests #92 (Configure React Testing Library and Setup Tests)
3. ⬅️ [3/N] Add unit tests for SideButton component #94 (Add unit tests for SideButton component)
4. ⬅️ [4/N] Add unit tests for SearchFilter component #95 (Add unit tests for SearchFilter component)
5. ⬅️ [5/N] Add unit tests for Header and Footer components #96 (Add unit tests for Header and Footer components)
6. ⬅️ [6/N] Add unit tests for Blob mascot component #97 (Add unit tests for Blob mascot component)
7. ⬅️ [7/N] Add unit tests for AboutScreen screen #98 (Add unit tests for AboutScreen screen)
8. ⬅️ [8/N] Add integration tests for HomeScreen screen #99 (Add integration tests for HomeScreen screen)
9. ⬅️ [9/N] Add unit tests for AlgorithmNotFound404 component #100 (Add unit tests for AlgorithmNotFound404 component)
10. ⬅️ [10/N] Add integration tests for AlgoScreen screen #101 (Add integration tests for AlgoScreen screen)
11. ⬅️ [11/N] Add unit tests for ModalSidebarSectionTab component #102 (Add unit tests for ModalSidebarSectionTab component)
12. ⬅️ [12/N] Add unit tests for BigOModal component #103 (Add unit tests for BigOModal component)
13. ⬅️ [13/N] Add unit tests for Pseudocode component #104 (Add unit tests for Pseudocode component)
14. ⬅️ [14/N] Add unit and integration tests for AlgoSection component #105 (Add unit and integration tests for AlgoSection component)
15. ⬅️ [15/N] Add unit and integration tests for root App component #106 (Add unit and integration tests for root App component)
16. ⬅️ [16/N] Add unit tests for animation events and undo functions #107 (Add unit tests for animation events and undo functions)
17. ⬅️ [17/N] Add unit tests for AnimatedObject, AnimatedCircle, and AnimatedHighlightCircle #108 (Add unit tests for AnimatedObject, AnimatedCircle, and AnimatedHighlightCircle)
18. ⬅️ [18/N] Add unit tests for AnimatedRectangle, AnimatedLabel, and AnimatedLine #109 (Add unit tests for AnimatedRectangle, AnimatedLabel, and AnimatedLine)
19. ⬅️ [19/N] Add unit tests for AnimatedLinkedListNode, AnimatedDoublyLinkedListNode, and AnimatedCircularlyLinkedListNode #110 (Add unit tests for AnimatedLinkedListNode, AnimatedDoublyLinkedListNode, and AnimatedCircularlyLinkedListNode)
20. ⬅️ [20/N] Add unit tests for AnimatedBTreeNode and AnimatedSkipListNode #111 (Add unit tests for AnimatedBTreeNode and AnimatedSkipListNode)
21. ⬅️ [21/N] Add unit tests for ObjectManager #112 (Add unit tests for ObjectManager)
22. ⬅️ [22/N] Add unit tests for AnimationMain #113 (Add unit tests for AnimationMain)
23. 👉 #CURRENT — Add unit tests for algo util helpers (PriorityQueue, SkipListHeads, GraphValues) (this PR)
24. ➡️ [24/N] Add unit tests for base Algorithm class and control bar helpers #115 (Add unit tests for base Algorithm class and control bar helpers)

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Addresses #93

Context

Adds unit test coverage for the standalone utility modules located in src/algo/util/, which power data structures and graph algorithms throughout the visualizer:

• PriorityQueue.js: Min-priority queue implementation used in Dijkstra's, Prim's, and Huffman coding animations.
• SkipListHeads.js: Seed head-count sequence used for reproducible SkipList tower animations.
• GraphValues.js: Graph topology definitions, logical coordinates, curve layouts, color palettes, and adjacency matrices for BFS/DFS, Dijkstra's, Floyd-Warshall, Prim's, and Kruskal's algorithms.

Changes Made

• Introduced src/algo/util/__tests__/PriorityQueue.test.js covering:
• Queue initialization (backingArray, size(), getIDs()).
• Priority sorting ascending (lower priority dequeued first).
• Tie-breaking logic:
• Scalar data comparison.
• Array-based data comparison on first index (a[0][0] - b[0][0]).
• Array-based data comparison on secondary index (a[0][1] - b[0][1]).
• Dequeue payload formatting ([data, id]) and dynamic size tracking.
• Introduced src/algo/util/__tests__/SkipListHeads.test.js covering:
• Array structure and length validation (1000 items).
• Value bounding ([0, 4] range validation).
• Introduced src/algo/util/__tests__/GraphValues.test.js covering:
• Small graph (8 vertices) and large graph (18 vertices) logical coordinate arrays (SMALL_X_POS_LOGICAL, SMALL_Y_POS_LOGICAL, LARGE_X_POS_LOGICAL, LARGE_Y_POS_LOGICAL).
• Allowance boolean matrices and curve matrices (SMALL_ALLLOWED, LARGE_ALLOWED, SMALL_CURVE, LARGE_CURVE).
• Adjacency list matrices (BFS_DFS_ADJ_LIST, DIJKSTRAS_ADJ_LIST, FLOYD_ADJ_LIST, PRIMS_KRUSKALS_ADJ_LIST, LARGE_ADJ_LIST).
• Disjoint set color palette verification (KRUSKALS_DS_COLORS).

Test Plan

• Ran npm test -- --watchAll=false (all 32 test suites pass).
• Ran npm run lint and npm run prettier.
• Verified 100% statement, function, and branch coverage on all files in src/algo/util/.