@dash0/sdk-web/dist/modules/utils/pick_test.js

Dash0's Web SDK to collect telemetry from end-users' web browsers

import { describe, it, expect } from "vitest";
import { pick } from "./pick";
describe("pick", () => {
    it("should pick specified properties from an object", () => {
        const source = {
            name: "John",
            age: 30,
            email: "john@example.com",
            city: "New York",
        };
        const result = pick(source, ["name", "age"]);
        expect(result).toEqual({
            name: "John",
            age: 30,
        });
    });
    it("should return empty object when picking from empty object", () => {
        const source = {};
        const result = pick(source, ["name", "age"]);
        expect(result).toEqual({});
    });
    it("should handle picking non-existent properties", () => {
        const source = {
            name: "John",
            age: 30,
        };
        const result = pick(source, ["name", "nonExistent"]);
        expect(result).toEqual({
            name: "John",
        });
    });
    it("should pick all properties when all keys are specified", () => {
        const source = {
            a: 1,
            b: 2,
            c: 3,
        };
        const result = pick(source, ["a", "b", "c"]);
        expect(result).toEqual(source);
        expect(result).not.toBe(source); // Should be a new object
    });
    it("should return empty object when no keys are specified", () => {
        const source = {
            name: "John",
            age: 30,
        };
        const result = pick(source, []);
        expect(result).toEqual({});
    });
    it("should preserve property values including falsy ones", () => {
        const source = {
            name: "",
            age: 0,
            active: false,
            data: null,
            info: undefined,
        };
        const result = pick(source, ["name", "age", "active", "data", "info"]);
        expect(result).toEqual({
            name: "",
            age: 0,
            active: false,
            data: null,
            info: undefined,
        });
    });
    it("should work with nested objects", () => {
        const source = {
            user: {
                name: "John",
                age: 30,
            },
            settings: {
                theme: "dark",
            },
            isActive: true,
        };
        const result = pick(source, ["user", "isActive"]);
        expect(result).toEqual({
            user: {
                name: "John",
                age: 30,
            },
            isActive: true,
        });
        expect(result.user).toBe(source.user); // Should reference the same nested object
    });
    it("should maintain type safety", () => {
        const user = {
            id: 1,
            name: "John",
            email: "john@example.com",
            isActive: true,
        };
        const result = pick(user, ["id", "name"]);
        // TypeScript should infer the type as Pick<User, 'id' | 'name'>
        expect(result.id).toBe(1);
        expect(result.name).toBe("John");
        expect(result).toEqual({
            id: 1,
            name: "John",
        });
    });
});