Fixed String Bytes Test

1import { describe, expect, it } from "vitest";
2import { query } from "./clickhouse.js";
3import { NeedMoreData, Cursor } from "../src/readers/core.js";
4import { readFixedStringBytes } from "../src/readers/strings.js";
5
6async function reader(expr: string): Promise<Cursor> {
7  return new Cursor(await query(`SELECT ${expr} FORMAT RowBinary`));
8}
9
10describe("readFixedStringBytes", () => {
11  it("returns the raw bytes, padding included", async () => {
12    const r = await reader("toFixedString('ab', 4)");
13    expect(readFixedStringBytes(4)(r)).toEqual(Buffer.from([0x61, 0x62, 0, 0]));
14    expect(r.pos).toBe(4);
15  });
16
17  // The default is a zero-copy view, so it shares memory with the source.
18  it("returns a zero-copy view sharing memory", async () => {
19    const r = await reader("toFixedString('ab', 4)");
20    const bytes = readFixedStringBytes(4)(r);
21    r.buf[0] = 0xff;
22    expect(bytes[0]).toBe(0xff);
23  });
24
25  describe("advance() edge cases", () => {
26    it("throws NeedMoreData for every incomplete prefix (0 .. full.length-1)", async () => {
27      const full = await query(
28        "SELECT toFixedString('ab', 4) FORMAT RowBinary",
29      );
30      for (let len = 0; len < full.length; len++) {
31        const r = new Cursor(full.subarray(0, len));
32        let thrown: unknown;
33        try {
34          readFixedStringBytes(4)(r);
35        } catch (e) {
36          thrown = e;
37        }
38        expect(thrown, `prefix length ${len} of ${full.length}`).toBe(
39          NeedMoreData,
40        );
41      }
42    });
43  });
44});