ts-prime/src/clone.test.ts

A utility library for JavaScript and Typescript.

import * as assert from 'assert';
import { clone } from './clone';

const eq = (a: any, b: any) => {
  expect(a).toEqual(b);
};

describe('deep clone integers, strings and booleans', () => {
  it('clones integers', () => {
    eq(clone(-4), -4);
    eq(clone(9007199254740991), 9007199254740991);
  });

  it('clones floats', () => {
    eq(clone(-4.5), -4.5);
    eq(clone(0.0), 0.0);
  });

  it('clones strings', () => {
    eq(clone('foo'), 'foo');
  });

  it('clones booleans', () => {
    eq(clone(true), true);
  });
});

describe('deep clone objects', () => {
  it('clones shallow object', () => {
    const obj = { a: 1, b: 'foo', c: true, d: new Date(2013, 11, 25) };
    const cloned = clone(obj);
    obj.c = false;
    obj.d.setDate(31);
    assert.notStrictEqual(cloned, { a: 1, b: 'foo', c: true, d: new Date(2013, 11, 25) });
  });

  it('clones deep object', () => {
    const obj = { a: { b: { c: 'foo' } } };
    const cloned = clone(obj);
    obj.a.b.c = 'bar';
    eq(cloned, { a: { b: { c: 'foo' } } });
  });

  it('clones objects with circular references', () => {
    const x: any = { c: null };
    const y = { a: x };
    const z = { b: y };
    x.c = z;
    const cloned = clone(x);
    assert.notStrictEqual(x, cloned);
    assert.notStrictEqual(x.c, cloned.c);
    assert.notStrictEqual(x.c.b, cloned.c.b);
    assert.notStrictEqual(x.c.b.a, cloned.c.b.a);
    assert.notStrictEqual(x.c.b.a.c, cloned.c.b.a.c);
    eq(Object.keys(cloned), Object.keys(x));
    eq(Object.keys(cloned.c), Object.keys(x.c));
    eq(Object.keys(cloned.c.b), Object.keys(x.c.b));
    eq(Object.keys(cloned.c.b.a), Object.keys(x.c.b.a));
    eq(Object.keys(cloned.c.b.a.c), Object.keys(x.c.b.a.c));

    x.c.b = 1;
    assert.notDeepEqual(cloned.c.b, x.c.b);
  });

  // it('clone instances', () => {
  //   const Obj = function(x) {
  //     this.x = x;
  //   };
  //   Obj.prototype.get = () => {
  //     return this.x;
  //   };
  //   Obj.prototype.set = function(x) {
  //     this.x = x;
  //   };

  //   const obj = new Obj(10);
  //   eq(obj.get(), 10);

  //   const cloned = clone(obj);
  //   eq(cloned.get(), 10);

  //   assert.notStrictEqual(obj, cloned);

  //   obj.set(11);
  //   eq(obj.get(), 11);
  //   eq(cloned.get(), 10);
  // });
});

describe('deep clone arrays', () => {
  it('clones shallow arrays', () => {
    const list = [1, 2, 3];
    const cloned = clone(list);
    list.pop();
    eq(cloned, [1, 2, 3]);
  });

  it('clones deep arrays', () => {
    const list: any = [1, [1, 2, 3], [[[5]]]];
    const cloned = clone(list);

    assert.notStrictEqual(list, cloned);
    assert.notStrictEqual(list[2], cloned[2]);
    assert.notStrictEqual(list[2][0], cloned[2][0]);

    eq(cloned, [1, [1, 2, 3], [[[5]]]]);
  });
});

describe('deep clone functions', () => {
  it('keep reference to function', () => {
    const fn = (x: any) => {
      return x + x;
    };
    const list = [{ a: fn }];

    const cloned = clone(list);

    eq(cloned[0].a(10), 20);
    eq(list[0].a, cloned[0].a);
  });
});

describe('built-in types', () => {
  it('clones Date object', () => {
    const date = new Date(2014, 10, 14, 23, 59, 59, 999);

    const cloned = clone(date);

    eq(date, cloned);
    eq(cloned, new Date(2014, 10, 14, 23, 59, 59, 999));

    eq(cloned.getDay(), 5); // friday
  });

  it('clones RegExp object', () => {
    [/x/, /x/g, /x/i, /x/m, /x/gi, /x/gm, /x/im, /x/gim].forEach(pattern => {
      const cloned = clone(pattern);
      assert.notStrictEqual(cloned, pattern);
      eq(cloned.constructor, RegExp);
      eq(cloned.source, pattern.source);
      eq(cloned.global, pattern.global);
      eq(cloned.ignoreCase, pattern.ignoreCase);
      eq(cloned.multiline, pattern.multiline);
    });
  });
});

describe('deep clone deep nested mixed objects', () => {
  it('clones array with objects', () => {
    const list: any = [{ a: { b: 1 } }, [{ c: { d: 1 } }]];
    const cloned = clone(list);
    list[1][0] = null;
    eq(cloned, [{ a: { b: 1 } }, [{ c: { d: 1 } }]]);
  });

  it('clones array with arrays', () => {
    const list: any[][] = [[1], [[3]]];
    const cloned = clone(list);
    list[1][0] = null;
    eq(cloned, [[1], [[3]]]);
  });

  it('clones array with mutual ref object', () => {
    const obj = { a: 1 };
    const list = [{ b: obj }, { b: obj }];
    const cloned = clone(list);

    assert.strictEqual(list[0].b, list[1].b);
    assert.strictEqual(cloned[0].b, cloned[1].b);
    assert.notStrictEqual(cloned[0].b, list[0].b);
    assert.notStrictEqual(cloned[1].b, list[1].b);

    eq(cloned[0].b, { a: 1 });
    eq(cloned[1].b, { a: 1 });

    obj.a = 2;
    eq(cloned[0].b, { a: 1 });
    eq(cloned[1].b, { a: 1 });
  });
});

describe('deep clone edge cases', () => {
  it('nulls, undefineds and empty objects and arrays', () => {
    eq(clone(null), null);
    eq(clone(undefined), undefined);
    assert.notStrictEqual(clone(undefined), null);

    const obj = {};
    assert.notStrictEqual(clone(obj), obj);

    const list: any = [];
    assert.notStrictEqual(clone(list), list);
  });
});

// describe('Let `clone` use an arbitrary user defined `clone` method', () => {
//   it('dispatches to `clone` method if present', () => {
//     function ArbitraryClone(x: any) {
//       this.value = x;
//     }
//     ArbitraryClone.prototype.clone = () => {
//       return new ArbitraryClone(this.value);
//     };

//     const obj = new ArbitraryClone(42);
//     const arbitraryClonedObj = clone(obj);
//     eq(arbitraryClonedObj, new ArbitraryClone(42));
//     eq(arbitraryClonedObj instanceof ArbitraryClone, true);
//   });
// });