A Jasmine test util that uses a TypeScript class or an instance of a class to create a mock instance of that class.
import { SomeClass } from 'some-library';
import { MockFactory} from 'jasmine-mock-factory';
it('should pass', () => {
const mockInstance = MockFactory.create(SomeClass);
/* arrange */
mockInstance._spy.doSomething._func.and.returnValue('awesome!');
/* act */
mockInstance.doSomething(); // returns 'awesome!'
/* assert */
expect(mockInstance.doSomething).toHaveBeenCalled();
} /* create a mock from a class*/
const mockInstance1 = MockFactory.create(RealClass);
/* create a mock from an instance*/
const mockInstance2 = MockFactory.create(realInstance);
/* access a function spy */
const spy1 = mockInstance._spy.functionName._func
/* access a getter spy */
const spy2 = mockInstance._spy.propertyName._get
/* access a setter spy */
const spy3 = mockInstance._spy.propertyName._set- This util is built with and for Jasmine test framework. Basic understanding of Jasmine is assumed.
- This util requires ES6 Proxy.
npm install jasmine-mock-factory --save-devImport the library with ES6 Module Syntax:
import { MockFactory } from 'jasmine-mock-factory'class RealClass {
// This is a typescript class
}
...
const mockInstance = MockFactory.create(RealClass);const realInstance: RealInterface = new RealClass();
...
const mockInstance = MockFactory.create(realInstance);/* make sure you have included dom types from the TypeScript library */
const mockWindow = MockFactory.create(window);
const mockDocument = MockFactory.create(document);
const mockLocation = MockFactory.create(location);MockFactory.create()will return an object with the same interface as the real object. You can invoke functions and access properties on this object.- In addition, the mock object provides a
_spyfacade, where you can access and config spies on functions and properties.
const mockInstance = MockFactory.create(location);
mockInstance.reload(); // use it as if it were the real window.location
let temp = mockInstance.search; // use it as if it were the real window.search
mockInstance.hash = 'myHash'; // use it as if it were the real window.hash
mockInstance._spy.reload._func; // returns the spy behind location.reload
mockInstance._spy.search._get; // returns the spy behind the getter for location.search
mockInstance._spy.hash._set; // returns the spy behind the setter for location.hash- All functions will have a
jasmine.Spyas the initial value. The spy cannot be overwritten and returnsundefinedby default. - To access protected and private functions, cast the mockInstance
as anyor use bracket notation.
mockInstance.publicFunction(42); // the spy behind it is invoked with 42
(mockInstance as any).privateFunction(42);
mockInstance['privateFunction'](42); // equivalent- You can change return values of functions or assert their calls by accessing them directly or through the
_spyfacade. - Access a function spy on
mockInstance._spy.functionName._func.
/* stubbing a public function */
mockInstance._spy.publicFunction._func.and.returnValue(42);
(mockInstance.publicFunction as jasmine.Spy).and.returnValue(42); // equivalent, but not recommented because it requires casting
/* stubbing a private function */
mockInstance._spy.privateFunction._func.and.returnValue(42);
((mockInstance as any).privateFunction as jasmine.Spy).and.returnValue(42); // equivalent, but not recommented because it requires casting twice- All properties have
undefinedas the initial value. The value can be overwritten with anything. - You have read and write access to any property, even if they were readonly in the real object.
- To read or write a protected or private property, cast the mockInstance
as anyor use bracket notation. - To write a readonly property, cast the mockInstance
as any. The bracket notation won't work. - By default, modification to the properties will persist, even if a getter or setter exists in the real object.
/* persist modification */
mockInstance.publicProperty = 42;
let temp = mockInstance.publicProperty; // temp = 42;
/* access readonly property */
mockInstance.readonlyProperty = 42; // typescript compiler error
(mockInstance as any).readonlyProperty = 42; // no problem
mockInstance['readonlyProperty'] = 42; // typescript compiler error
/* access private property */
(mockInstance as any).privateProperty = 'foo';
mockInstance['privateProperty'] = 'foo'; // equivalent- All properties have spies on the getter and setter, even if the getter and setter don't exist in the real object.
- Access a getter spy on
mockInstance._spy.propertyName._get. - Access a setter spy on
mockInstance._spy.propertyName._set. - NOTE: modification to the properties will not persist after getter or setter spies are customized
- NOTE:
expect(mockInstance.someProperty).toBe(...)will triggermockInstance._spy.someProperty._get. Design the sequence of your assertions carefully to avoid shooting yourself in the foot.
/* assert getter calls */
let temp = mockInstance.publicProperty;
expect(mockInstance._spy.publicProperty._get).toHaveBeenCalled();
/* assert setter calls on a public property */
mockInstance.publicProperty = 42;
expect(mockInstance._spy.publicProperty._set).toHaveBeenCalledWith(42);
/* customize setter */
expect(mockInstance.publicProperty).toBe(42); // pass. setter hasn't been customized
mockInstance._spy.publicProperty._set.and.callFake(() => { /* noop */});
mockInstance.publicProperty = 100;
expect(mockInstance.publicProperty).toBe(100); // fail. expect 42 to be 100. setter was customized
/* assert setter calls on a private property */
mockInstance['privateProperty'] = 42;
expect(mockInstance._spy.privateProperty._set).toHaveBeenCalledWith(42);
/* customize getter */
expect(mockInstance['privateProperty']).toBe(42); // pass. getter hasn't been customized
mockInstance._spy.privateProperty._get.and.returnValue(100);
mockInstance['privateProperty'] = 42;
expect(mockInstance['privateProperty']).toBe(42); // fail, expect 100 to be 42. getter was customziednpm installto install dev dependenciesnpm run buildto build the librarynpm run testto test the library
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