javascript - Trying to use Jasmine spies and getting "is not a function" errors -

here class:

class clock {    // runs callback while continues   // returns truthy values    constructor(callback, delay) {     this.callback = callback;     this.delay = delay;     this.timerid = null;   }    start() {     this.timerid = settimeout(() => {       if (this.callback.call()) this.start();     }, this.delay);   }    // want kill time?    kill() {     cleartimeout(this.timerid);   }  }  export default clock; 

and relevant tests:

import clock '../../src/js/lib/clock.js';  describe("clock", function() {    it("has callback , delay", function() {     let clock = clockfactory();     expect(clock.callback).tobedefined();     expect(clock.delay).tobedefined();   });    describe("is clock", function() {     let observer,     clock;      beforeeach(function() {       jasmine.clock().install();        observer = { callback: function() {} };       spyon(observer, 'callback')       console.log(observer)        clock = clockfactory({callback: observer});     });      aftereach(function() {       jasmine.clock().uninstall();       clock.kill()     });      it("it periodically executes callback", function() {       clock.start()       expect(observer.callback).not.tohavebeencalled();        jasmine.clock().tick(5001);       expect(observer.callback.calls.count()).toequal(1);        jasmine.clock().tick(2500);       expect(observer.callback.calls.count()).toequal(1);        jasmine.clock().tick(2500);       expect(observer.callback.calls.count()).toequal(2);     });      it("it can stop ticking", function() {       clock.start()       expect(observer.callback).not.tohavebeencalled();        jasmine.clock().tick(5001);       expect(observer.callback.calls.count()).toequal(1);        clock.kill()        jasmine.clock().tick(5000);       expect(observer.callback.calls.count()).toequal(1);     });    });    function clockfactory(options = {}) {     return new clock(       (options.callback || function() {}),       options.delay || 5000       );   }  }); 

now when run tests, following failures:

failures: 1) clock clock periodically executes callback   message:     typeerror: _this.callback.call not function   stack:     typeerror: _this.callback.call not function         @ clock.js:14:25         @ object.<anonymous> (clock_spec.js:34:23)  2) clock clock can stop ticking   message:     typeerror: _this.callback.call not function   stack:     typeerror: _this.callback.call not function         @ clock.js:14:25         @ object.<anonymous> (clock_spec.js:48:23) 

i think i'm using spies correctly based on examples, evidently there problem! suggestions?

your clock constructor expects function (or @ least object call() method) first argument. in tests, invoking clockfactory like

observer = { callback: function () {} }; spyon(observer, 'callback'); clock = clockfactory({ callback: observer }); 

i.e. first argument being passed clockfactory is

{ callback: { callback: function () {} } } 

this not intended (unless clockfactory signature not match clock constructor signature). try doing like

observer = jasmine.createspy('observer'); clock = clockfactory(observer); 

---

alternatively, can use "options object" pattern in clock constructor , write like

constructor({callback, delay}) {   this.callback = callback;   this.delay = delay;   ... } 

then, can pass single object callback , delay properties, like

observer = { callback: function () {} }; spyon(observer, 'callback'); clock = clockfactory(observer);