/**
* Tests for pagination utilities
*/
import {
encodeCursor,
decodeCursor,
paginate,
DEFAULT_PAGE_SIZE,
} from "../../src/utils/pagination.js";
describe("Pagination", () => {
describe("encodeCursor", () => {
it("should encode a cursor", () => {
const cursor = encodeCursor(0);
expect(typeof cursor).toBe("string");
expect(cursor.length).toBeGreaterThan(0);
});
it("should encode different offsets differently", () => {
const cursor1 = encodeCursor(0);
const cursor2 = encodeCursor(50);
expect(cursor1).not.toBe(cursor2);
});
it("should be base64 encoded", () => {
const cursor = encodeCursor(100);
// Base64 regex
expect(cursor).toMatch(/^[A-Za-z0-9+/]*={0,2}$/);
});
});
describe("decodeCursor", () => {
it("should decode a valid cursor", () => {
const cursor = encodeCursor(42);
const offset = decodeCursor(cursor);
expect(offset).toBe(42);
});
it("should return 0 for undefined cursor", () => {
const offset = decodeCursor(undefined);
expect(offset).toBe(0);
});
it("should return 0 for invalid cursor", () => {
const offset = decodeCursor("invalid-base64");
expect(offset).toBe(0);
});
it("should return 0 for negative offsets", () => {
const cursor = Buffer.from(JSON.stringify({ offset: -10 })).toString("base64");
const offset = decodeCursor(cursor);
expect(offset).toBe(0);
});
it("should round-trip correctly", () => {
const original = 123;
const cursor = encodeCursor(original);
const decoded = decodeCursor(cursor);
expect(decoded).toBe(original);
});
});
describe("paginate", () => {
const items = Array.from({ length: 100 }, (_, i) => i);
it("should return first page when no cursor provided", () => {
const result = paginate(items, undefined, 10);
expect(result.items).toHaveLength(10);
expect(result.items[0]).toBe(0);
expect(result.items[9]).toBe(9);
expect(result.nextCursor).toBeDefined();
});
it("should return correct page with cursor", () => {
const cursor = encodeCursor(10);
const result = paginate(items, cursor, 10);
expect(result.items).toHaveLength(10);
expect(result.items[0]).toBe(10);
expect(result.items[9]).toBe(19);
});
it("should return nextCursor when there are more items", () => {
const result = paginate(items, undefined, 10);
expect(result.nextCursor).toBeDefined();
const nextCursor = result.nextCursor;
if (nextCursor) {
const nextOffset = decodeCursor(nextCursor);
expect(nextOffset).toBe(10);
}
});
it("should not return nextCursor on last page", () => {
const cursor = encodeCursor(90);
const result = paginate(items, cursor, 10);
expect(result.items).toHaveLength(10);
expect(result.nextCursor).toBeUndefined();
});
it("should handle partial last page", () => {
const cursor = encodeCursor(95);
const result = paginate(items, cursor, 10);
expect(result.items).toHaveLength(5);
expect(result.items[0]).toBe(95);
expect(result.items[4]).toBe(99);
expect(result.nextCursor).toBeUndefined();
});
it("should use default page size", () => {
const result = paginate(items, undefined);
expect(result.items).toHaveLength(Math.min(DEFAULT_PAGE_SIZE, items.length));
});
it("should handle empty array", () => {
const result = paginate([], undefined, 10);
expect(result.items).toHaveLength(0);
expect(result.nextCursor).toBeUndefined();
});
it("should handle array smaller than page size", () => {
const smallArray = [1, 2, 3];
const result = paginate(smallArray, undefined, 10);
expect(result.items).toHaveLength(3);
expect(result.nextCursor).toBeUndefined();
});
it("should handle cursor beyond array length", () => {
const cursor = encodeCursor(200);
const result = paginate(items, cursor, 10);
expect(result.items).toHaveLength(0);
expect(result.nextCursor).toBeUndefined();
});
it("should support iterating through all pages", () => {
const pageSize = 10;
const allItems: number[] = [];
let cursor: string | undefined = undefined;
while (true) {
const result: { items: number[]; nextCursor?: string } = paginate(
items,
cursor,
pageSize
);
allItems.push(...result.items);
if (!result.nextCursor) {
break;
}
cursor = result.nextCursor;
}
expect(allItems).toEqual(items);
});
});
});
