Cache Class Helper Unit Test Example

Cache.test.js

import Cache from '~/helper/Cache'

describe('Cache class', ()=>{
    test('get method retrieves items from the cache', ()=>{
        const cache = new Cache()
        cache.put('hello', 'world')
        expect(cache.get('hello')).toBe('world')
    })
    test('put method adds items to the cache', ()=>{
        (new Cache).put('hello', 'world')
        expect((new Cache).get('hello')).toBe('world')
    })

    test('forget method removes items from the cache', ()=>{
        const cache = new Cache
        cache.put('hello', 'world')
        cache.forget('hello')

        expect(cache.get('hello')).toBeNull()
    })

    test('pull method return and removes', ()=>{
        const cache = new Cache
        cache.put('hello', 'world')
        const fromCache = cache.pull('hello')
        // retrieved first
        expect(fromCache).toBe('world')
        // then removed from cache
        expect(cache.get('hello')).toBeNull()
    })

    test('flush method completely eliminates all items from cache', ()=>{
        const cache = new Cache()
        cache.put('hello', 'world')
        cache.put('hola', 'spanish for world')
        cache.put('something else', 'im in the cache')

        cache.flush()
        // expect the default group to be empty
        expect( JSON.stringify(cache.all().default) ).toBe('{}')
        // and not other group to exist
        expect( Object.keys(cache.all()).length ).toBe(1)
    })

    test('expired items do not return from cache', (done)=>{
        const cache = new Cache()
        cache.expires(100).put('hello', 'world')
        // can still get before expires
        expect(cache.get('hello')).toBe('world')

        setTimeout(()=>{
            //null after expires
            expect(cache.get('hello')).toBeNull()
            done()
        }, 101)
    })

    test('group method adds items to named group', ()=>{
        const cache = new Cache()
        cache.group('cats')
        .put('fluffy', 'calico')
        .put('coco', 'siamese')

        expect( JSON.stringify(cache.getGroup('default'))).toBe('{}')
        expect( cache.group('cats').get('fluffy') ).toBe('calico')
    })

    test('method flushGroup flushes one group without altering other groups', ()=>{
        const cache = new Cache()
        cache.group('group 1').put('hello', 'world').put('another item', 'here i am ')
        cache.group('group 2').put('group 2 hello', 'world group 2').put('group 2 another item', 'here i am group 2')

        cache.flushGroup('group 2')

        expect( JSON.stringify(cache.getGroup('group 1')) ).not.toBe('{}')
        expect( JSON.stringify(cache.getGroup('group 2')) ).toBe('{}')
    })

    test('default value used if item not found in cache', ()=>{
        const cache = new Cache()
        const dude = cache.get('noexist', 'dude')
        expect(dude).toBe('dude')
    })

    test('default value can be callback functions', ()=>{
        const cache = new Cache()
        const dude = cache.get('noexist', ()=>{
            return 'dude'
        })
        expect(dude).toBe('dude')
    })
})

afterEach(() => {
    (new Cache).flush()
});