How do you mock process.platform in jasmine tests?

Question

How do you mock process.platform using jasmine specs?

Answer 1

You can use Object.defineProperty() to set value of process.platform in beforeAll and then reset it to original in afterAll after tests are finished.

If you print of Object.getOwnPropertyDescriptor(process, "platform") to get descriptor configuration of platform.process in node.js console then you will get following:

{ value: 'darwin',
  writable: false,
  enumerable: true,
  configurable: true }

As you can see, value of process.platform is not writable (see docs for more information) so you can't set it using assignment operator. but you can override it using Object.defineProperty.

Jasmine Example

describe('test process platform', function(){
    beforeAll(function(){
       this.originalPlatform = process.platform;
       Object.defineProperty(process, 'platform', {  
         value: 'MockOS'
       });
    });

    it(/*test*/);

    ....

    it(/*test*/);

    afterAll(function(){
       Object.defineProperty(process, 'platform', {  
         value: this.originalPlatform
       });
    });
});

Object.defineProperty() Docs