import { Queue } from '../queue';

type QueueConstructor = new <T>() => Queue<T>
export function testQueue(Queue: QueueConstructor) {
	it("enqueue should add a new element to the queue", () => {
		const queue = new Queue<number>();
		queue.enqueue(1);
		expect(queue.length()).toBe(1);
	});

	it("isEmpty should return true on empty queue", () => {
		const queue = new Queue<number>();
		expect(queue.isEmpty()).toBeTruthy();
	});

	it("isEmpty should return false on not empty queue", () => {
		const queue = new Queue<number>();
		queue.enqueue(1);
		expect(queue.isEmpty()).toBeFalsy();
	});

	it("front should return the first value", () => {
		const queue = new Queue<number>();
		queue.enqueue(1);
		expect(queue.peek()).toBe(1);
	});

	it("front should return null when the queue is empty", () => {
		const queue = new Queue<number>();
		expect(queue.peek()).toBe(null);
	});

	it("length should return the number of elements in the queue", () => {
		const queue = new Queue<number>();
		queue.enqueue(1);
		queue.enqueue(1);
		queue.enqueue(1);
		expect(queue.length()).toBe(3);
	});

	it("dequeue should remove the first element", () => {
		const queue = new Queue<number>();
		queue.enqueue(1);
		queue.enqueue(2);
		queue.enqueue(3);
		queue.dequeue();
		expect(queue.length()).toBe(2);
	});

	it("dequeue should throw error on empty queue", () => {
		const queue = new Queue<number>();
		expect(() => queue.dequeue()).toThrow("Queue Underflow");
	});
}