import { describe, expect, it } from "vitest";
import { asArray, asNumber, asRecord, asString } from "./projection";

describe("projection guards", () => {
  it("asRecord accepts plain objects only", () => {
    expect(asRecord({ a: 1 })).toEqual({ a: 1 });
    expect(asRecord([1])).toBeNull();
    expect(asRecord("x")).toBeNull();
    expect(asRecord(null)).toBeNull();
  });

  it("asString / asNumber narrow primitives", () => {
    expect(asString("s")).toBe("s");
    expect(asString(1)).toBeNull();
    expect(asNumber(4)).toBe(4);
    expect(asNumber("4")).toBeNull();
    expect(asNumber(NaN)).toBeNull();
  });

  it("asArray defaults to empty", () => {
    expect(asArray([1, 2])).toEqual([1, 2]);
    expect(asArray(undefined)).toEqual([]);
    expect(asArray({})).toEqual([]);
  });
});