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Last active October 22, 2023 12:22
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Mock localStorage for jasmine tests in TypeScript. This is the testing script. Copy the parts between snip and snap to mock your localStorage
/// <reference path="../../library.test.d.ts"/>
import * as angular from "angular"; angular;
import * as mocks from "angular-mocks/ngMock"; mocks;
describe('feat(localStorage Mock): ', function() {
beforeAll(() => {
angular.module('mock-module',[])
});
// --- snip ---
// Mock localStorage
beforeEach(() => {
var store = {};
spyOn(localStorage, 'getItem').and.callFake( (key:string):String => {
return store[key] || null;
});
spyOn(localStorage, 'removeItem').and.callFake((key:string):void => {
delete store[key];
});
spyOn(localStorage, 'setItem').and.callFake((key:string, value:string):string => {
return store[key] = <string>value;
});
spyOn(localStorage, 'clear').and.callFake(() => {
store = {};
});
});
// --- snap ---
beforeEach(()=> {
angular.mock.module('mock-module');
});
it('should set an Item', () => {
expect(localStorage.setItem('foo', 'bar')).toBe('bar'); // bar
expect(localStorage.getItem('foo')).toBe('bar'); // bar
});
it('should return null for non existing items', () => {
expect(localStorage.getItem('foo')).toBeNull(); // null
});
it('should set and remove Item', () => {
expect(localStorage.setItem('foo', 'bar')).toBe('bar'); // bar
expect(localStorage.removeItem('foo')).toBeUndefined(); // undefined
expect(localStorage.getItem('foo')).toBeNull(); // null
});
it('should clear the storage', () => {
expect(localStorage.setItem('foo', 'bar')).toBe('bar'); // bar
expect(localStorage.setItem('bar', 'foo')).toBe('foo'); // foo
expect(localStorage.clear()).toBeUndefined(); // undefined
expect(localStorage.getItem('foo')).toBeNull(); // null
expect(localStorage.getItem('bar')).toBeNull(); // null
});
});
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ghost commented Sep 16, 2019

Good Lord, I just saw this response, sorry.
I have have too many accounts. :)
my thought was import a JSON full of values into the mocked storage, instead of adding 1 at a time , then simply verify they exist in the storage. Like if you added lots of information from a API call.

That was my thought anyways :)

@ayarushin
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For sessionStorage

Using spyOn(sessionStorage, 'getItem') not worked for me.
This approach works well with Angular 7

beforeEach(() => {
    ...

    let store = {};
    const mockSessionStorage = {
      getItem: (key: string): string => key in store ? store[key] : null,
      setItem: (key: string, value: string) => store[key] = `${value}`,
      removeItem: (key: string) => delete store[key],
      clear: () => store = {}
    };

    spyOn(Storage.prototype, 'getItem').and.callFake(mockSessionStorage.getItem);
    spyOn(Storage.prototype, 'setItem').and.callFake(mockSessionStorage.setItem);
    spyOn(Storage.prototype, 'removeItem').and.callFake(mockSessionStorage.removeItem);
    spyOn(Storage.prototype, 'clear').and.callFake(mockSessionStorage.clear);
});

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