d2/src/logger/__tests__/Logger.spec.js

Javascript library for DHIS2

import Logger from '../Logger'

describe('Logger', () => {
    let logger
    let consoleMock

    beforeEach(() => {
        consoleMock = {
            log: jest.fn(),
            debug: jest.fn(),
            error: jest.fn(),
            warn: jest.fn(),
        }

        logger = new Logger(consoleMock)
    })

    it('should not be allowed to be called without new', () => {
        expect(() => Logger()).toThrowErrorMatchingSnapshot()
    })

    it('should get the correct Logger instance from the namespace', () => {
        expect(logger).toBeInstanceOf(Logger)
    })

    it('should have a log function', () => {
        expect(logger.log).toBeDefined()
        expect(logger.log).toBeInstanceOf(Function)
    })

    it('should log to the console', () => {
        logger.log('my message')

        expect(consoleMock.log).toBeCalledWith('my message')
    })

    it('should return true after successful logging', () => {
        expect(logger.log('my message')).toBe(true)
    })

    it('should not log when it does not exist', () => {
        delete consoleMock.log

        expect(logger.log('my message')).toBe(false)
    })

    it('should not log if the method does not exist', () => {
        delete consoleMock.warn

        expect(logger.warn('my message')).toBe(false)
    })

    it('should log a warning', () => {
        expect(logger.warn('my message')).toBe(true)
        expect(consoleMock.warn).toBeCalledWith('my message')
    })

    it('should log a debug request', () => {
        expect(logger.debug('my message')).toBe(true)
        expect(consoleMock.debug).toBeCalledWith('my message')
    })

    it('should not log when it does not exist', () => {
        delete consoleMock.debug

        expect(logger.debug('my message')).toBe(false)
    })

    it('should log an error request', () => {
        expect(logger.error('my message')).toBe(true)
        expect(consoleMock.error).toBeCalledWith('my message')
    })

    it('should not log when error does not exist', () => {
        delete consoleMock.error

        expect(logger.error('my message')).toBe(false)
    })

    describe('getLogger', () => {
        it('should return a logger', () => {
            expect(Logger.getLogger()).toBeInstanceOf(Logger)
        })

        it('should create a singleton and return that', () => {
            expect(Logger.getLogger()).toBe(Logger.getLogger())
        })
    })
})