import { describe, expect, test } from "bun:test";
import { difference, every, intersects, union } from "../set";

describe("difference", () => {
	test("returns elements in a but not in b", () => {
		const result = difference(new Set([1, 2, 3]), new Set([2, 3, 4]));
		expect(result).toEqual(new Set([1]));
	});

	test("returns empty set when a is subset of b", () => {
		expect(difference(new Set([1, 2]), new Set([1, 2, 3]))).toEqual(new Set());
	});

	test("returns a when b is empty", () => {
		expect(difference(new Set([1, 2]), new Set())).toEqual(new Set([1, 2]));
	});
});

describe("intersects", () => {
	test("returns true when sets share elements", () => {
		expect(intersects(new Set([1, 2]), new Set([2, 3]))).toBe(true);
	});

	test("returns false when sets are disjoint", () => {
		expect(intersects(new Set([1, 2]), new Set([3, 4]))).toBe(false);
	});

	test("returns false for empty sets", () => {
		expect(intersects(new Set(), new Set([1]))).toBe(false);
		expect(intersects(new Set([1]), new Set())).toBe(false);
	});
});

describe("every", () => {
	test("returns true when a is subset of b", () => {
		expect(every(new Set([1, 2]), new Set([1, 2, 3]))).toBe(true);
	});

	test("returns false when a has elements not in b", () => {
		expect(every(new Set([1, 4]), new Set([1, 2, 3]))).toBe(false);
	});

	test("returns true for empty a", () => {
		expect(every(new Set(), new Set([1, 2]))).toBe(true);
	});
});

describe("union", () => {
	test("combines both sets", () => {
		const result = union(new Set([1, 2]), new Set([3, 4]));
		expect(result).toEqual(new Set([1, 2, 3, 4]));
	});

	test("deduplicates shared elements", () => {
		const result = union(new Set([1, 2]), new Set([2, 3]));
		expect(result).toEqual(new Set([1, 2, 3]));
	});

	test("handles empty sets", () => {
		expect(union(new Set(), new Set([1]))).toEqual(new Set([1]));
		expect(union(new Set([1]), new Set())).toEqual(new Set([1]));
	});
});