```ts
import { assertEquals } from "assert";

function chunk<T>(items: readonly T[], size: number): T[][] {
  if (size < 1) {
    throw new Error("Chunk size must be a positive integer");
  }

  const result: T[][] = [];
  for (let i = 0; i < items.length; i += size) {
    result.push(items.slice(i, Math.min(i + size, items.length)));
  }
  return result;
}

function testChunk() {
  // Test cases
  assertEquals(chunk([], 1), []);
  assertEquals(chunk([1], 2), [[1]]);
  assertEquals(chunk([1, 2, 3, 4, 5], 2), [[1, 2], [3, 4], [5]]);
}

testChunk();
```