initiative/packages/domain/src/__tests__/persistent-damage.test.ts

import { describe, expect, it } from "vitest";
import {
	addPersistentDamage,
	type PersistentDamageType,
	removePersistentDamage,
} from "../persistent-damage.js";
import type { Encounter } from "../types.js";
import { combatantId } from "../types.js";

const goblinId = combatantId("goblin-1");

function buildEncounter(overrides: Partial<Encounter> = {}): Encounter {
	return {
		combatants: [
			{
				id: goblinId,
				name: "Goblin",
				...overrides.combatants?.[0],
			},
		],
		activeIndex: overrides.activeIndex ?? 0,
		roundNumber: overrides.roundNumber ?? 1,
	};
}

describe("addPersistentDamage", () => {
	it("adds persistent fire damage to combatant", () => {
		const encounter = buildEncounter();
		const result = addPersistentDamage(encounter, goblinId, "fire", "2d6");

		expect(result).not.toHaveProperty("kind");
		if ("kind" in result) return;

		const target = result.encounter.combatants[0];
		expect(target.persistentDamage).toEqual([{ type: "fire", formula: "2d6" }]);
		expect(result.events).toEqual([
			{
				type: "PersistentDamageAdded",
				combatantId: goblinId,
				damageType: "fire",
				formula: "2d6",
			},
		]);
	});

	it("replaces existing entry of same type with new formula", () => {
		const encounter = buildEncounter({
			combatants: [
				{
					id: goblinId,
					name: "Goblin",
					persistentDamage: [{ type: "fire", formula: "2d6" }],
				},
			],
		});
		const result = addPersistentDamage(encounter, goblinId, "fire", "3d6");

		expect(result).not.toHaveProperty("kind");
		if ("kind" in result) return;

		expect(result.encounter.combatants[0].persistentDamage).toEqual([
			{ type: "fire", formula: "3d6" },
		]);
	});

	it("allows multiple different damage types", () => {
		const encounter = buildEncounter({
			combatants: [
				{
					id: goblinId,
					name: "Goblin",
					persistentDamage: [{ type: "fire", formula: "2d6" }],
				},
			],
		});
		const result = addPersistentDamage(encounter, goblinId, "bleed", "1d4");

		expect(result).not.toHaveProperty("kind");
		if ("kind" in result) return;

		expect(result.encounter.combatants[0].persistentDamage).toEqual([
			{ type: "fire", formula: "2d6" },
			{ type: "bleed", formula: "1d4" },
		]);
	});

	it("sorts entries by definition order", () => {
		const encounter = buildEncounter({
			combatants: [
				{
					id: goblinId,
					name: "Goblin",
					persistentDamage: [{ type: "cold", formula: "1d6" }],
				},
			],
		});
		const result = addPersistentDamage(encounter, goblinId, "fire", "2d6");

		expect(result).not.toHaveProperty("kind");
		if ("kind" in result) return;

		const types = result.encounter.combatants[0].persistentDamage?.map(
			(e) => e.type,
		);
		expect(types).toEqual(["fire", "cold"]);
	});

	it("returns domain error for empty formula", () => {
		const encounter = buildEncounter();
		const result = addPersistentDamage(encounter, goblinId, "fire", "  ");

		expect(result).toHaveProperty("kind", "domain-error");
		if (!("kind" in result)) return;
		expect(result.code).toBe("empty-formula");
	});

	it("returns domain error for unknown damage type", () => {
		const encounter = buildEncounter();
		const result = addPersistentDamage(
			encounter,
			goblinId,
			"radiant" as PersistentDamageType,
			"2d6",
		);

		expect(result).toHaveProperty("kind", "domain-error");
		if (!("kind" in result)) return;
		expect(result.code).toBe("unknown-damage-type");
	});

	it("returns domain error for unknown combatant", () => {
		const encounter = buildEncounter();
		const result = addPersistentDamage(
			encounter,
			combatantId("nonexistent"),
			"fire",
			"2d6",
		);

		expect(result).toHaveProperty("kind", "domain-error");
		if (!("kind" in result)) return;
		expect(result.code).toBe("combatant-not-found");
	});

	it("trims formula whitespace", () => {
		const encounter = buildEncounter();
		const result = addPersistentDamage(encounter, goblinId, "fire", "  2d6  ");

		expect(result).not.toHaveProperty("kind");
		if ("kind" in result) return;

		expect(result.encounter.combatants[0].persistentDamage?.[0].formula).toBe(
			"2d6",
		);
	});

	it("does not mutate input encounter", () => {
		const encounter = buildEncounter();
		const originalCombatants = encounter.combatants;
		addPersistentDamage(encounter, goblinId, "fire", "2d6");

		expect(encounter.combatants).toBe(originalCombatants);
		expect(encounter.combatants[0].persistentDamage).toBeUndefined();
	});
});

describe("removePersistentDamage", () => {
	it("removes existing persistent damage entry", () => {
		const encounter = buildEncounter({
			combatants: [
				{
					id: goblinId,
					name: "Goblin",
					persistentDamage: [
						{ type: "fire", formula: "2d6" },
						{ type: "bleed", formula: "1d4" },
					],
				},
			],
		});
		const result = removePersistentDamage(encounter, goblinId, "fire");

		expect(result).not.toHaveProperty("kind");
		if ("kind" in result) return;

		expect(result.encounter.combatants[0].persistentDamage).toEqual([
			{ type: "bleed", formula: "1d4" },
		]);
		expect(result.events).toEqual([
			{
				type: "PersistentDamageRemoved",
				combatantId: goblinId,
				damageType: "fire",
			},
		]);
	});

	it("sets persistentDamage to undefined when last entry removed", () => {
		const encounter = buildEncounter({
			combatants: [
				{
					id: goblinId,
					name: "Goblin",
					persistentDamage: [{ type: "fire", formula: "2d6" }],
				},
			],
		});
		const result = removePersistentDamage(encounter, goblinId, "fire");

		expect(result).not.toHaveProperty("kind");
		if ("kind" in result) return;

		expect(result.encounter.combatants[0].persistentDamage).toBeUndefined();
	});

	it("returns domain error when damage type not active", () => {
		const encounter = buildEncounter();
		const result = removePersistentDamage(encounter, goblinId, "fire");

		expect(result).toHaveProperty("kind", "domain-error");
		if (!("kind" in result)) return;
		expect(result.code).toBe("persistent-damage-not-active");
	});

	it("returns domain error for unknown combatant", () => {
		const encounter = buildEncounter();
		const result = removePersistentDamage(
			encounter,
			combatantId("nonexistent"),
			"fire",
		);

		expect(result).toHaveProperty("kind", "domain-error");
		if (!("kind" in result)) return;
		expect(result.code).toBe("combatant-not-found");
	});
});