project-inter-server/test/types/CircularQueue.test.ts

import { describe, expect, it } from "@jest/globals";
import { CircularQueue } from "../../src/types/CircularQueue";

interface TestItem {
  id: number;
  value: string;
}

describe("CircularQueue", () => {
  const testItems = {
    first: { id: 1, value: "first" },
    second: { id: 2, value: "second" },
    third: { id: 3, value: "third" },
    fourth: { id: 4, value: "fourth" },
    test: { id: 1, value: "test" },
    apple: { id: 1, value: "apple" },
    banana: { id: 2, value: "banana" },
    cherry: { id: 3, value: "cherry" },
    grape: { id: 5, value: "grape" },
    orange: { id: 7, value: "orange" },
    a: { id: 1, value: "a" },
    b: { id: 2, value: "b" },
    c: { id: 3, value: "c" },
    d: { id: 4, value: "d" }
  };

  const sortingCallbacks = {
    byId: (a: TestItem, b: TestItem) => a.id - b.id,
    byValue: (a: TestItem, b: TestItem) => a.value.localeCompare(b.value)
  };

  const keyExtractors = {
    id: (item: TestItem) => item.id,
    value: (item: TestItem) => item.value
  };

  const createQueueWithItems = (size: number, items: TestItem[], sortingCallback: (a: TestItem, b: TestItem) => number) => {
    const queue = new CircularQueue<TestItem>(size);
    items.forEach(item => queue.appendWithSorting(item, sortingCallback));
    return queue;
  };

  describe("constructor", () => {
    it("creates queue with specified size", () => {
      const queue = new CircularQueue<TestItem>(5);
      expect(queue).toBeDefined();
    });
  });

  describe("appendWithSorting", () => {
    it("adds items to the queue with sorting callback", () => {
      const queue = createQueueWithItems(3, [testItems.third, testItems.first, testItems.second], sortingCallbacks.byId);

      expect(queue.size()).toBe(3);
      expect(queue.get(0)).toEqual(testItems.first);
      expect(queue.get(1)).toEqual(testItems.second);
      expect(queue.get(2)).toEqual(testItems.third);
    });

    it("overwrites oldest items when queue is full", () => {
      const queue = createQueueWithItems(2, [testItems.first, testItems.second, testItems.third], sortingCallbacks.byId);

      expect(queue.size()).toBe(2);
    });

    it("handles appending to empty queue", () => {
      const queue = createQueueWithItems(3, [testItems.test], sortingCallbacks.byId);

      expect(queue.size()).toBe(1);
      expect(queue.get(0)).toEqual(testItems.test);
    });

    it("optimizes append when items are already in order", () => {
      const queue = new CircularQueue<TestItem>(5);
      let sortCallCount = 0;

      const trackingSortCallback = (a: TestItem, b: TestItem) => {
        sortCallCount++;
        return a.id - b.id;
      };

      queue.appendWithSorting(testItems.first, trackingSortCallback);
      expect(sortCallCount).toBe(0);

      queue.appendWithSorting(testItems.second, trackingSortCallback);
      expect(sortCallCount).toBe(1);

      queue.appendWithSorting(testItems.third, trackingSortCallback);
      expect(sortCallCount).toBe(2);

      queue.appendWithSorting({ id: 0, value: "zero" }, trackingSortCallback);
      expect(sortCallCount).toBeGreaterThan(3);

      expect(queue.get(0)).toEqual({ id: 0, value: "zero" });
      expect(queue.get(1)).toEqual(testItems.first);
    });
  });

  describe("popFront", () => {
    it("removes the oldest item from queue", () => {
      const queue = createQueueWithItems(3, [testItems.first, testItems.second], sortingCallbacks.byId);

      expect(queue.size()).toBe(2);
      queue.popFront();
      expect(queue.size()).toBe(1);
      expect(queue.get(0)).toEqual(testItems.second);
    });

    it("handles popping from empty queue", () => {
      const queue = new CircularQueue<TestItem>(3);

      expect(() => queue.popFront()).not.toThrow();
      expect(queue.size()).toBe(0);
    });

    it("handles popping until empty", () => {
      const queue = createQueueWithItems(2, [testItems.first, testItems.second], sortingCallbacks.byId);

      queue.popFront();
      expect(queue.size()).toBe(1);
      queue.popFront();
      expect(queue.size()).toBe(0);
      queue.popFront();
      expect(queue.size()).toBe(0);
    });
  });

  describe("binarySearch", () => {
    it("finds item using key extractor function", () => {
      const queue = createQueueWithItems(5, [testItems.apple, testItems.cherry, testItems.grape, testItems.orange], sortingCallbacks.byId);

      const result = queue.binarySearch(5, keyExtractors.id);

      expect(result).toEqual(testItems.grape);
    });

    it("returns undefined when item not found", () => {
      const queue = createQueueWithItems(5, [testItems.apple, testItems.cherry, testItems.orange], sortingCallbacks.byId);

      const result = queue.binarySearch(5, keyExtractors.id);

      expect(result).toBeUndefined();
    });

    it("finds first item", () => {
      const queue = createQueueWithItems(5, [testItems.apple, testItems.cherry, testItems.orange], sortingCallbacks.byId);

      const result = queue.binarySearch(1, keyExtractors.id);

      expect(result).toEqual(testItems.apple);
    });

    it("finds last item", () => {
      const queue = createQueueWithItems(5, [testItems.apple, testItems.cherry, testItems.orange], sortingCallbacks.byId);

      const result = queue.binarySearch(7, keyExtractors.id);

      expect(result).toEqual(testItems.orange);
    });

    it("returns undefined for empty queue", () => {
      const queue = new CircularQueue<TestItem>(5);
      const result = queue.binarySearch(1, keyExtractors.id);

      expect(result).toBeUndefined();
    });

    it("works with string keys", () => {
      const queue = createQueueWithItems(5, [testItems.apple, testItems.banana, testItems.cherry], sortingCallbacks.byValue);

      const result = queue.binarySearch("banana", keyExtractors.value);

      expect(result).toEqual(testItems.banana);
    });

    it("maintains sorted order assumption", () => {
      const queue = createQueueWithItems(5, [testItems.d, testItems.a, testItems.c, testItems.b], sortingCallbacks.byValue);

      expect(queue.binarySearch("a", keyExtractors.value)).toEqual(testItems.a);
      expect(queue.binarySearch("b", keyExtractors.value)).toEqual(testItems.b);
      expect(queue.binarySearch("c", keyExtractors.value)).toEqual(testItems.c);
      expect(queue.binarySearch("d", keyExtractors.value)).toEqual(testItems.d);
      expect(queue.binarySearch("z", keyExtractors.value)).toBeUndefined();
    });
  });

  describe("integration", () => {
    it("handles appendWithSorting, popFront, and binarySearch together", () => {
      const queue = createQueueWithItems(3, [testItems.third, testItems.first, testItems.second], sortingCallbacks.byId);

      expect(queue.binarySearch(2, keyExtractors.id)).toEqual(testItems.second);

      queue.popFront();
      expect(queue.binarySearch(1, keyExtractors.id)).toBeUndefined();
      expect(queue.binarySearch(2, keyExtractors.id)).toEqual(testItems.second);

      queue.appendWithSorting(testItems.fourth, sortingCallbacks.byId);
      expect(queue.binarySearch(4, keyExtractors.id)).toEqual(testItems.fourth);
    });
  });
});