Decimal64 Test

1import { describe, expect, it } from "vitest";
2import { query } from "./clickhouse.js";
3import { NeedMoreData, Cursor } from "../src/readers/core.js";
4import { formatDecimal, readDecimal64 } from "../src/readers/decimals.js";
5
6async function reader(expr: string): Promise<Cursor> {
7  return new Cursor(await query(`SELECT ${expr} FORMAT RowBinary`));
8}
9
10describe("readDecimal64", () => {
11  it("decodes -12.34 at scale 2", async () => {
12    const r = await reader("toDecimal64(-12.34, 2)");
13    const dec = readDecimal64(2)(r);
14    expect(dec).toEqual([-1234n, 2]);
15    expect(r.pos).toBe(8);
16    expect(formatDecimal(dec)).toBe("-12.34");
17  });
18
19  it("keeps the declared scale's trailing zero in the raw value", async () => {
20    const dec = readDecimal64(2)(await reader("toDecimal64(1.20, 2)"));
21    expect(dec).toEqual([120n, 2]);
22    // CH text would show "1.2"; formatDecimal keeps the scale: "1.20".
23    expect(formatDecimal(dec)).toBe("1.20");
24  });
25
26  describe("advance() edge cases", () => {
27    it("throws NeedMoreData for every incomplete prefix (0 .. full.length-1)", async () => {
28      const full = await query(
29        "SELECT toDecimal64(-12.34, 2) FORMAT RowBinary",
30      );
31      for (let len = 0; len < full.length; len++) {
32        const r = new Cursor(full.subarray(0, len));
33        let thrown: unknown;
34        try {
35          readDecimal64(2)(r);
36        } catch (e) {
37          thrown = e;
38        }
39        expect(thrown, `prefix length ${len} of ${full.length}`).toBe(
40          NeedMoreData,
41        );
42      }
43    });
44  });
45});