Read Header Test

1import { describe, expect, it } from "vitest";
2import { query } from "./clickhouse.js";
3import { Cursor } from "../src/readers/core.js";
4import { readHeader } from "../src/readers/header.js";
5
6/** Fetch a `RowBinaryWithNamesAndTypes` response (header + rows) as a cursor. */
7async function withNamesAndTypes(select: string): Promise<Cursor> {
8  return new Cursor(await query(`${select} FORMAT RowBinaryWithNamesAndTypes`));
9}
10
11describe("readHeader", () => {
12  it("reads column count, names, then types and stops at the first row", async () => {
13    const s = await withNamesAndTypes("SELECT toUInt32(7) AS id, 'x' AS name");
14
15    expect(readHeader(s)).toEqual({
16      names: ["id", "name"],
17      types: ["UInt32", "String"],
18    });
19    // Cursor now points at the row payload (the first column's UInt32).
20    expect(s.buf.readUInt32LE(s.pos)).toBe(7);
21  });
22});