Array Test

1import { describe, expect, it } from "vitest";
2import { query } from "./clickhouse.js";
3import { readArray, readNullable } from "../src/readers/composite.js";
4import { NeedMoreData, Cursor } from "../src/readers/core.js";
5import { readUInt32, readUInt8 } from "../src/readers/integers.js";
6import { readString } from "../src/readers/strings.js";
7
8async function reader(expr: string): Promise<Cursor> {
9  return new Cursor(await query(`SELECT ${expr} FORMAT RowBinary`));
10}
11
12describe("readArray", () => {
13  it("decodes a fixed-width element array", async () => {
14    const r = await reader("CAST([1, 2, 3] AS Array(UInt32))");
15    expect(readArray(readUInt32)(r)).toEqual([1, 2, 3]);
16    expect(r.pos).toBe(13); // 1 count + 3 * 4
17  });
18
19  it("decodes the empty array (just the count byte)", async () => {
20    const r = await reader("CAST([] AS Array(UInt32))");
21    expect(readArray(readUInt32)(r)).toEqual([]);
22    expect(r.pos).toBe(1);
23  });
24
25  it("decodes a variable-length element array", async () => {
26    const r = await reader("CAST(['a', 'bb'] AS Array(String))");
27    expect(readArray(readString)(r)).toEqual(["a", "bb"]);
28  });
29
30  // Nesting composes by nesting the element reader.
31  it("decodes Array(Array(UInt8))", async () => {
32    const r = await reader("CAST([[1], [2, 3]] AS Array(Array(UInt8)))");
33    expect(readArray(readArray(readUInt8))(r)).toEqual([[1], [2, 3]]);
34  });
35
36  // Composes with Nullable: the NULL element is just its flag byte.
37  it("decodes Array(Nullable(UInt8)) with a NULL element", async () => {
38    const r = await reader("CAST([1, NULL, 3] AS Array(Nullable(UInt8)))");
39    expect(readArray(readNullable(readUInt8))(r)).toEqual([1, null, 3]);
40  });
41
42  describe("advance() edge cases", () => {
43    it("throws NeedMoreData for every incomplete prefix (0 .. full.length-1)", async () => {
44      const full = await query(
45        "SELECT CAST([1, 2, 3] AS Array(UInt32)) FORMAT RowBinary",
46      );
47      for (let len = 0; len < full.length; len++) {
48        const r = new Cursor(full.subarray(0, len));
49        let thrown: unknown;
50        try {
51          readArray(readUInt32)(r);
52        } catch (e) {
53          thrown = e;
54        }
55        expect(thrown, `prefix length ${len} of ${full.length}`).toBe(
56          NeedMoreData,
57        );
58      }
59    });
60  });
61});