ts-prime/src/deepMerge.test.ts

A utility library for JavaScript and Typescript.

import { deepMergeLeft, deepMergeRight } from './deepMerge';

describe('mergeDeepLeft and mergeRight tests', () => {
  test('basic', () => {
    interface Item {
      a: number; // C1
      b?: number; // C2
      d: {
        e: {
          a?: number; // C3 nested object
        };
        d?: () => void; // C4 function
      };
      y?: {
        a: number;
      };
    }
    const data1: Item = {
      a: 1,
      d: {
        e: {
          a: 5,
        },
      },
    };
    const fn = () => {
      return;
    };
    const data2: Item = {
      a: 2,
      b: 3,
      d: {
        d: fn,
        e: {
          a: 4,
        },
      },
    };
    expect(deepMergeLeft(data1, data2)).toEqual({
      a: 1, // From data1
      d: {
        d: fn, // From data 2
        e: {
          a: 5, // From data1
        },
      },
      b: 3, // From data2
    });

    expect(deepMergeRight(data1, data2)).toEqual({
      a: 2, // From data2
      d: {
        d: fn, // From data 2
        e: {
          a: 4, // From data2
        },
      },
      b: 3, // From data2
    });
  });

  interface Data {
    a: (number | { a: number })[];
  }
  const d1: Data = {
    a: [1, 2, 3, { a: 1 }],
  };
  const d2: Data = {
    a: [7, 2, 3, { a: 1 }, { a: 2 }],
  };
  test('Expecting correctly merged arrays', () => {
    expect(deepMergeLeft(d1, d2)).toEqual({
      a: [1, 2, 3, { a: 1 }, 7, { a: 1 }, { a: 2 }],
    });

    expect(deepMergeRight(d1, d2)).toEqual({
      a: [7, 2, 3, { a: 1 }, { a: 2 }, 1, { a: 1 }],
    });
  });

  test('Testing cycle objects', () => {
    interface Data {
      a: Data | null | number;
    }

    let data1: Data = {
      a: null,
    };
    data1.a = data1; // Creating cycle

    let data2: Data = {
      a: 5,
    };

    expect(deepMergeLeft(data1, data2)).toEqual({
      a: data1,
    });

    expect(deepMergeRight(data1, data2)).toEqual({
      a: 5,
    });
  });

  test('Testing cycle arrays', () => {
    interface Data {
      a: ReadonlyArray<Data | null | number>;
    }

    let data1: Data = {
      a: [],
    };
    data1.a = [data1]; // Creating cycle

    let data2: Data = {
      a: [5],
    };

    expect(deepMergeLeft(data1, data2)).toEqual({
      a: [data1],
    });

    expect(deepMergeRight(data1, data2)).toEqual({
      a: [5, data1],
    });
  });

  test('Complicated example', () => {
    const source1: any = {
      propS1: 'str1',
      propS2: 'str2',
      propN1: 1,
      propN2: 2,
      propA1: [1, 2, 3],
      propA2: [],
      propB1: true,
      propB2: false,
      propU1: null,
      propU2: null,
      propD1: undefined,
      propD2: undefined,
      propO1: {
        subS1: 'sub11',
        subS2: 'sub12',
        subN1: 11,
        subN2: 12,
        subA1: [11, 12, 13],
        subA2: [],
        subB1: false,
        subB2: true,
        subU1: null,
        subU2: null,
        subD1: undefined,
        subD2: undefined,
        propX1Deep: {
          a: {
            subS1: 'sub11',
            subS2: 'sub12',
            subN1: 11,
            subN2: 12,
            subA1: [11, 12, 13],
            subA2: [],
            subB1: false,
            subB2: true,
            subU1: null,
            subU2: null,
            subD1: undefined,
            subD2: undefined,
          },
        },
      },
      propO2: {
        subS1: 'sub21',
        subS2: 'sub22',
        subN1: 21,
        subN2: 22,
        subA1: [21, 22, 23],
        subA2: [],
        subB1: false,
        subB2: true,
        subU1: null,
        subU2: null,
        subD1: undefined,
        subD2: undefined,
      },
    };
    const clone = { ...source1 };
    const source2: any = {
      propS2: 'str2',
      propS3: 'str3',
      propN2: -2,
      propN3: 3,
      propA2: [2, 2],
      propA3: [3, 2, 1],
      propB2: true,
      propB3: false,
      propU2: 'not null',
      propU3: null,
      propD2: 'defined',
      propD3: undefined,
      propO2: {
        subS2: 'inv22',
        subS3: 'sub23',
        subN2: -22,
        subN3: 23,
        subA2: [5, 5, 5],
        subA3: [31, 32, 33],
        subB2: false,
        subB3: true,
        subU2: 'not null --- ',
        subU3: null,
        subD2: ' not undefined ----',
        subD3: undefined,
      },
      propO3: {
        subS1: 'sub31',
        subS2: 'sub32',
        subN1: 31,
        subN2: 32,
        subA1: [31, 32, 33],
        subA2: [],
        subB1: false,
        subB2: true,
        subU1: null,
        subU2: null,
        subD1: undefined,
        subD2: undefined,
      },
    };
    expect(deepMergeLeft(source1, source2)).toEqual({
      propA1: [1, 2, 3],
      propA2: [2],
      propA3: [3, 2, 1],
      propB1: true,
      propB2: false,
      propB3: false,
      propD1: undefined,
      propD2: 'defined',
      propD3: undefined,
      propN1: 1,
      propN2: 2,
      propN3: 3,
      propO1: {
        propX1Deep: {
          a: {
            subA1: [11, 12, 13],
            subA2: [],
            subB1: false,
            subB2: true,
            subD1: undefined,
            subD2: undefined,
            subN1: 11,
            subN2: 12,
            subS1: 'sub11',
            subS2: 'sub12',
            subU1: null,
            subU2: null,
          },
        },
        subA1: [11, 12, 13],
        subA2: [],
        subB1: false,
        subB2: true,
        subD1: undefined,
        subD2: undefined,
        subN1: 11,
        subN2: 12,
        subS1: 'sub11',
        subS2: 'sub12',
        subU1: null,
        subU2: null,
      },
      propO2: {
        subA1: [21, 22, 23],
        subA2: [5],
        subA3: [31, 32, 33],
        subB1: false,
        subB2: true,
        subB3: true,
        subD1: undefined,
        subD2: ' not undefined ----',
        subD3: undefined,
        subN1: 21,
        subN2: 22,
        subN3: 23,
        subS1: 'sub21',
        subS2: 'sub22',
        subS3: 'sub23',
        subU1: undefined,
        subU2: 'not null --- ',
        subU3: null,
      },
      propO3: {
        subA1: [31, 32, 33],
        subA2: [],
        subB1: false,
        subB2: true,
        subD1: undefined,
        subD2: undefined,
        subN1: 31,
        subN2: 32,
        subS1: 'sub31',
        subS2: 'sub32',
        subU1: null,
        subU2: null,
      },
      propS1: 'str1',
      propS2: 'str2',
      propS3: 'str3',
      propU1: undefined,
      propU2: 'not null',
      propU3: null,
    });
    expect(source1).toEqual(clone);
  });
});