pixi-demo/tests/chase/chaseGenerator.test.ts

import { describe, expect, it } from "vitest";
import { shortestPathLength } from "../../src/game/chase/hexGraph";
import { generateChaseRound } from "../../src/game/chase/generator";
import type { Difficulty } from "../../src/game/chase/types";

describe("chase round generator", () => {
  it("is deterministic for same seed and difficulty", () => {
    const options = { seed: 20260426, difficulty: "normal" as Difficulty };
    const roundA = generateChaseRound(options);
    const roundB = generateChaseRound(options);

    expect(roundA).toEqual(roundB);
  });

  it("matches golden snapshot for fixed seed", () => {
    const round = generateChaseRound({ seed: 424242, difficulty: "easy" });

    expect({
      seed: round.snapshot.seed,
      difficulty: round.snapshot.difficulty,
      thiefStartNodeId: round.snapshot.thiefStartNodeId,
      guardStartNodeId: round.snapshot.guardStartNodeId,
      thiefNodeId: round.snapshot.thiefNodeId,
      guardNodeId: round.snapshot.guardNodeId,
      exitNodeId: round.snapshot.exitNodeId,
      status: round.snapshot.status,
      hasEscapePath: round.meta.hasEscapePath,
      nodeCount: Object.keys(round.snapshot.graph.nodes).length,
      edgeCount: round.snapshot.graph.edgeList.length,
      firstFiveNodeIds: Object.keys(round.snapshot.graph.nodes).slice(0, 5),
    }).toMatchInlineSnapshot(`
      {
        "difficulty": "easy",
        "edgeCount": 19,
        "exitNodeId": "0,-1",
        "firstFiveNodeIds": [
          "0,0",
          "1,-1",
          "2,-2",
          "2,-1",
          "1,-2",
        ],
        "guardNodeId": "0,0",
        "guardStartNodeId": "0,0",
        "hasEscapePath": true,
        "nodeCount": 20,
        "seed": 424242,
        "status": "playing",
        "thiefNodeId": "4,-5",
        "thiefStartNodeId": "4,-5",
      }
    `);
  });

  it("generates graph node count between 20 and 30", () => {
    const round = generateChaseRound({ seed: 11, difficulty: "normal" });
    const nodeCount = Object.keys(round.snapshot.graph.nodes).length;
    expect(nodeCount).toBeGreaterThanOrEqual(20);
    expect(nodeCount).toBeLessThanOrEqual(30);
  });

  it("ensures an escape path exists", () => {
    const round = generateChaseRound({ seed: 99, difficulty: "hard" });
    const pathLength = shortestPathLength(
      round.snapshot.graph,
      round.snapshot.thiefNodeId,
      round.snapshot.exitNodeId,
    );

    expect(round.meta.hasEscapePath).toBe(true);
    expect(pathLength).toBeGreaterThan(0);
    expect(pathLength).toBeLessThan(Infinity);
  });

  it("ensures thief and guard do not start on the same node", () => {
    const round = generateChaseRound({ seed: 123456, difficulty: "normal" });
    expect(round.snapshot.thiefStartNodeId).not.toBe(round.snapshot.guardStartNodeId);
  });

  it("stays playable and stable across many seeds", () => {
    for (let seed = 1; seed <= 60; seed += 1) {
      const round = generateChaseRound({ seed, difficulty: "normal" });
      const nodeCount = Object.keys(round.snapshot.graph.nodes).length;

      expect(nodeCount).toBeGreaterThanOrEqual(20);
      expect(nodeCount).toBeLessThanOrEqual(30);
      expect(round.meta.hasEscapePath).toBe(true);
      expect(round.snapshot.thiefStartNodeId).not.toBe(
        round.snapshot.guardStartNodeId,
      );
    }
  });

  it("throws after retry limit when all attempts are unplayable", () => {
    let attemptCount = 0;
    const unplayableStrategy = (seed: number, difficulty: Difficulty) => {
      attemptCount += 1;
      return {
        snapshot: {
          seed,
          difficulty,
          graph: { nodes: {}, edgeList: [] },
          thiefStartNodeId: "A",
          guardStartNodeId: "A",
          thiefNodeId: "A",
          guardNodeId: "A",
          exitNodeId: "A",
          status: "playing" as const,
        },
        meta: {
          hasEscapePath: false,
          pathLength: 0,
          attemptsUsed: 1,
        },
      };
    };

    expect(() =>
      generateChaseRound(
        { seed: 7, difficulty: "normal" },
        { generateAttempt: unplayableStrategy },
      ),
    ).toThrow("Unable to generate playable chase round within retry limit");
    expect(attemptCount).toBe(40);
  });
});