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mattphillipsmattphillips
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Add array diff
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‎src/arrayDiff/index.js

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import { isDate, isEmpty, isObject, properObject } from '../utils';
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const diff = (lhs, rhs) => {
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if (lhs === rhs) return {}; // equal return no diff
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if (!isObject(lhs) || !isObject(rhs)) return rhs; // return updated rhs
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const l = properObject(lhs);
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const r = properObject(rhs);
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const deletedValues = Object.keys(l).reduce((acc, key) => {
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return r.hasOwnProperty(key) ? acc : { ...acc, [key]: undefined };
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}, {});
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if (isDate(l) || isDate(r)) {
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if (l.valueOf() == r.valueOf()) return {};
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return r;
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}
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if (Array.isArray(r) && Array.isArray(l)) {
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const deletedValues = l.reduce((acc, item, index) => {
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return r.hasOwnProperty(index) ? acc.concat(item) : acc.concat(undefined);
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}, []);
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return r.reduce((acc, rightItem, index) => {
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if (!deletedValues.hasOwnProperty(index)) {
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return acc.concat(rightItem);
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}
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const leftItem = l[index];
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const difference = diff(rightItem, leftItem);
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if (isObject(difference) && isEmpty(difference) && !isDate(difference)) {
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delete acc[index];
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return acc; // return no diff
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}
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return acc.slice(0, index).concat(rightItem).concat(acc.slice(index + 1)); // return updated key
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}, deletedValues);
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}
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return Object.keys(r).reduce((acc, key) => {
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if (!l.hasOwnProperty(key)) return { ...acc, [key]: r[key] }; // return added r key
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const difference = diff(l[key], r[key]);
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if (isObject(difference) && isEmpty(difference) && !isDate(difference)) return acc; // return no diff
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return { ...acc, [key]: difference }; // return updated key
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}, deletedValues);
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};
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export default diff;

‎src/arrayDiff/index.test.js

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import forEach from 'jest-each';
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import diff from './';
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describe('.arrayDiff', () => {
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describe('base case', () => {
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describe('equal', () => {
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forEach([
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['int', 1],
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['string', 'a'],
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['boolean', true],
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['null', null],
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['undefined', undefined],
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['object', { a: 1 }],
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['array', [1]],
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['function', () => ({})],
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['date', new Date()],
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['date with milliseconds', new Date('2017-01-01T00:00:00.637Z')],
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]).test('returns empty object when given values of type %s are equal', (type, value) => {
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expect(diff(value, value)).toEqual({});
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});
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});
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describe('not equal and not object', () => {
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forEach([
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[1, 2],
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['a', 'b'],
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[true, false],
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['hello', null],
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['hello', undefined],
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[null, undefined],
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[undefined, null],
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[null, { a: 1 }],
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['872983', { areaCode: '+44', number: '872983' }],
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[100, () => ({})],
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[() => ({}), 100],
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[new Date('2017-01-01'), new Date('2017-01-02')],
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[new Date('2017-01-01T00:00:00.636Z'), new Date('2017-01-01T00:00:00.637Z')],
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]).test('returns right hand side value when different to left hand side value (%s, %s)', (lhs, rhs) => {
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expect(diff(lhs, rhs)).toEqual(rhs);
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});
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});
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});
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describe('recursive case', () => {
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describe('object', () => {
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test('returns right hand side value when given objects are different', () => {
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expect(diff({ a: 1 }, { a: 2 })).toEqual({ a: 2 });
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});
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test('returns right hand side value when right hand side value is null', () => {
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expect(diff({ a: 1 }, { a: null })).toEqual({ a: null });
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});
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test('returns subset of right hand side value when sibling objects differ', () => {
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expect(diff({ a: { b: 1 }, c: 2 }, { a: { b: 1 }, c: 3 })).toEqual({ c: 3 });
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});
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test('returns subset of right hand side value when nested values differ', () => {
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expect(diff({ a: { b: 1, c: 2} }, { a: { b: 1, c: 3 } })).toEqual({ a: { c: 3 } });
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});
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test('returns subset of right hand side value when nested values differ at multiple paths', () => {
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expect(diff({ a: { b: 1 }, c: 2, d: { e: 100 } }, { a: { b: 99 }, c: 3, d: { e: 100 } })).toEqual({ a: { b: 99 }, c: 3 });
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});
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test('returns subset of right hand side value when a key value has been deleted', () => {
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expect(diff({ a: { b: 1 }, c: 2, d: { e: 100 } }, { a: { b: 1 }, c: 2, d: {} })).toEqual({ d: { e: undefined } });
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});
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test('returns subset of right hand side value when a key value has been added', () => {
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expect(diff({ a: 1 }, { a: 1, b: 2 })).toEqual({ b: 2 });
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});
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test('returns keys as undefined when deleted from right hand side', () => {
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expect(diff({ a: 1, b: { c: 2 }}, { a: 1 })).toEqual({ b: undefined });
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});
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});
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describe('arrays', () => {
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test('returns right hand side value as object of indices to value when arrays are different', () => {
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expect(diff([1], [2])).toEqual([2]);
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});
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test('returns subset of right hand side array as object of indices to value when arrays differs at multiple indicies', () => {
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const expected = [9, 8, 3];
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delete expected['2'];
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expect(diff([1, 2, 3], [9, 8, 3])).toEqual(expected);
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});
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test('returns subset of right hand side array as object of indices to value when right hand side array has deletions', () => {
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const expected = [1, 3, undefined];
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delete expected['0'];
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expect(diff([1, 2, 3], [1, 3])).toEqual(expected);
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});
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test('returns subset of right hand side array as object of indices to value when right hand side array has additions', () => {
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const expected = [1, 2, 3, 9];
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delete expected['0'];
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delete expected['1'];
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delete expected['2'];
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// expected.forEach(console.log)
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expect(diff([1, 2, 3], [1, 2, 3, 9])).toEqual(expected);
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});
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});
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describe('date', () => {
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const lhs = new Date('2016');
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const rhs = new Date('2017');
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test('returns empty object when dates are equal', () => {
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expect(diff(new Date('2016'), new Date('2016'))).toEqual({});
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});
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test('returns right hand side date when updated', () => {
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expect(diff({ date: lhs }, { date: rhs })).toEqual({ date: rhs });
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expect(diff([lhs], [rhs])).toEqual([rhs]);
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});
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test('returns undefined when date deleted', () => {
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expect(diff({ date: lhs }, {})).toEqual({ date: undefined });
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expect(diff([lhs], [])).toEqual([undefined]);
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});
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test('returns right hand side when date is added', () => {
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expect(diff({}, { date: rhs })).toEqual({ date: rhs });
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expect(diff([], [rhs])).toEqual([rhs]);
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});
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});
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describe('object create null', () => {
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test('returns right hand side value when given objects are different', () => {
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const lhs = Object.create(null);
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lhs.a = 1;
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const rhs = Object.create(null);
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rhs.a = 2;
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expect(diff(lhs, rhs)).toEqual({ a: 2 });
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});
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test('returns subset of right hand side value when sibling objects differ', () => {
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const lhs = Object.create(null);
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lhs.a = { b: 1 };
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lhs.c = 2;
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const rhs = Object.create(null);
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rhs.a = { b: 1 };
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rhs.c = 3;
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expect(diff(lhs, rhs)).toEqual({ c: 3 });
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});
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test('returns subset of right hand side value when nested values differ', () => {
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const lhs = Object.create(null);
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lhs.a = { b: 1, c: 2};
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const rhs = Object.create(null);
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rhs.a = { b: 1, c: 3 };
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expect(diff(lhs, rhs)).toEqual({ a: { c: 3 } });
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});
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test('returns subset of right hand side value when nested values differ at multiple paths', () => {
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const lhs = Object.create(null);
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lhs.a = { b: 1 };
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lhs.c = 2;
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const rhs = Object.create(null);
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rhs.a = { b: 99 };
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rhs.c = 3;
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expect(diff(lhs, rhs)).toEqual({ a: { b: 99 }, c: 3 });
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});
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test('returns subset of right hand side value when a key value has been deleted', () => {
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const lhs = Object.create(null);
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lhs.a = { b: 1 };
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lhs.c = 2;
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const rhs = Object.create(null);
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rhs.a = { b: 1 };
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expect(diff(lhs, rhs)).toEqual({ c: undefined });
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});
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test('returns subset of right hand side value when a key value has been added', () => {
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const lhs = Object.create(null);
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lhs.a = 1;
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const rhs = Object.create(null);
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rhs.a = 1;
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rhs.b = 2;
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expect(diff(lhs, rhs)).toEqual({ b: 2 });
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});
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});
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});
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});

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