Decimal32 Test

1import { describe, expect, it } from "vitest";
2import { query } from "./clickhouse.js";
3import { NeedMoreData, Cursor } from "../src/readers/core.js";
4import { formatDecimal, readDecimal32 } 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("readDecimal32", () => {
11  it("decodes 1.5 at scale 4 as [unscaled, scale]", async () => {
12    const r = await reader("toDecimal32(1.5, 4)");
13    const dec = readDecimal32(4)(r);
14    expect(dec).toEqual([15000n, 4]);
15    expect(r.pos).toBe(4);
16    // formatDecimal keeps the trailing zeros (CH text would show "1.5").
17    expect(formatDecimal(dec)).toBe("1.5000");
18  });
19
20  it("keeps a pure fraction lossless", async () => {
21    const dec = readDecimal32(3)(await reader("toDecimal32(0.005, 3)"));
22    expect(dec).toEqual([5n, 3]);
23    expect(formatDecimal(dec)).toBe("0.005");
24  });
25
26  it("decodes a negative value", async () => {
27    const dec = readDecimal32(4)(await reader("toDecimal32(-1.5, 4)"));
28    expect(dec).toEqual([-15000n, 4]);
29    expect(formatDecimal(dec)).toBe("-1.5000");
30  });
31
32  it("decodes scale 0 (formats with no decimal point)", async () => {
33    const dec = readDecimal32(0)(await reader("toDecimal32(42, 0)"));
34    expect(dec).toEqual([42n, 0]);
35    expect(formatDecimal(dec)).toBe("42");
36  });
37
38  describe("advance() edge cases", () => {
39    it("throws NeedMoreData for every incomplete prefix (0 .. full.length-1)", async () => {
40      const full = await query("SELECT toDecimal32(1.5, 4) FORMAT RowBinary");
41      for (let len = 0; len < full.length; len++) {
42        const r = new Cursor(full.subarray(0, len));
43        let thrown: unknown;
44        try {
45          readDecimal32(4)(r);
46        } catch (e) {
47          thrown = e;
48        }
49        expect(thrown, `prefix length ${len} of ${full.length}`).toBe(
50          NeedMoreData,
51        );
52      }
53    });
54  });
55});