it-tools/src/tools/json-to-csv/json-to-csv.service.test.ts

import { describe, expect, it } from 'vitest';
import { convertArrayToCsv, getHeaders } from './json-to-csv.service';

describe('json-to-csv service', () => {
  describe('getHeaders', () => {
    it('extracts all the keys from the array of nested objects', () => {
      expect(getHeaders({ array: [{ a: { c: 1, d: 1 }, b: 2 }, { a: 3, c: 4 }] })).toEqual(['a.c', 'a.d', 'b', 'a', 'c']);
    });

    it('extracts all the keys from the array of objects', () => {
      expect(getHeaders({ array: [{ a: 1, b: 2 }, { a: 3, c: 4 }] })).toEqual(['a', 'b', 'c']);
    });

    it('returns an empty array if the array is empty', () => {
      expect(getHeaders({ array: [] })).toEqual([]);
    });
  });

  describe('convertArrayToCsv', () => {
    it('converts an array of objects to a CSV string', () => {
      const array = [
        { a: 1, b: 2 },
        { a: 3, b: 4 },

      ];

      expect(convertArrayToCsv({ arrayOrObject: array })).toMatchInlineSnapshot(`
        "a,b
        1,2
        3,4"
      `);
    });

    it('converts an array of objects with different keys to a CSV string', () => {
      const array = [
        { a: 1, b: 2 },
        { a: 3, c: 4 },
      ];

      expect(convertArrayToCsv({ arrayOrObject: array })).toMatchInlineSnapshot(`
        "a,b,c
        1,2,
        3,,4"
      `);
    });

    it('when a value is null, it is converted to the string "null"', () => {
      const array = [
        { a: null, b: 2 },
      ];

      expect(convertArrayToCsv({ arrayOrObject: array })).toMatchInlineSnapshot(`
        "a,b
        null,2"
      `);
    });

    it('when a value is undefined, it is converted to an empty string', () => {
      const array = [
        { a: undefined, b: 2 },
        { b: 3 },
      ];

      expect(convertArrayToCsv({ arrayOrObject: array })).toMatchInlineSnapshot(`
        "a,b
        ,2
        ,3"
      `);
    });

    it('when a value contains a comma, it is wrapped in double quotes', () => {
      const array = [
        { a: 'hello, world', b: 2 },
      ];

      expect(convertArrayToCsv({ arrayOrObject: array })).toMatchInlineSnapshot(`
        "a,b
        \\"hello, world\\",2"
      `);
    });

    it('when a value contains a double quote, it is escaped with another double quote', () => {
      const array = [
        { a: 'hello "world"', b: 2 },
      ];

      expect(convertArrayToCsv({ arrayOrObject: array })).toMatchInlineSnapshot(`
        "a,b
        hello \\\\\\"world\\\\\\",2"
      `);
    });

    it('converts an array of nested objects to a CSV string', () => {
      const array = [
        { a: { c: 1, d: 1 }, b: 2 },
        { a: 3, c: 4 },
      ];

      expect(convertArrayToCsv({ arrayOrObject: array })).toMatchInlineSnapshot(`
        "a.c,a.d,b,a,c
        1,1,2,,
        ,,,3,4"
      `);
    });

    it('converts an object to a CSV string', () => {
      const obj = { a: { c: 1, d: 1 }, b: 2 };

      expect(convertArrayToCsv({ arrayOrObject: obj })).toMatchInlineSnapshot(`
        "a.c,a.d,b
        1,1,2"
      `);
    });
  });
});