What is the best way to simulate global variables that are declared in a separate file?

Question

What is the best way to simulate global variables that are declared in a separate file?

dataConfiguration.js

var userData = {
    URIs: {
        APIURI: "C" 
    },
    EncryptedToken: "D"
};

configSetup.js

config.set({
    basePath: '',
    files:['dataConfiguration.js' ],
    .....

UserComponentDetails:

.....some imports
import { UserDetailsService } from '../user-details.service';
declare var userData: any;
@Component({
    .....more code

    userFilter() {     
        return userData.URIs.APIURI;
    }
}

Testing:

describe('UserComponentDetails', () => {
    let subject:any;
    let fixture: ComponentFixture<UserComponentDetails>; 

    beforeEach(() => {
        TestBed.configureTestingModule({
            declarations: [ UserComponentDetails ],
            providers: [{ provide: UserDetailsService, useClass: 
            UserDetailsServiceStub }],
        });
        fixture = TestBed.createComponent(UserComponentDetails);
        subject = fixture.componentInstance;          
    });

    it('should return Z', () => {
        subject.userData = {
            URIs: {
                APIURI: "Z"
            },
            EncryptedToken: "W"
        };
        let result = subject.userFilter();
        expect(result).toBe("Z");
    });   
});

Result:

ReferenceError: userData is not defined

To resolve this issue, a method has been implemented inside the component to retrieve the userData global variable.

getUserData():any{
    return userData;
}

Additionally, mocking this method in the test suite:

let n = {
    URIs: {
        APIURI: "mockedValueAPIURI",
    },
    EncryptedToken: "mockedEncryptedToken",
};
let spy = spyOn(subject, 'getUserData').and.returnValue(n);

Is there a way to mock global variables like this without needing to wrap them in methods and then mock the method instead of the variable? The goal is to keep the original application code intact if written by someone else.

javascript angular typescript unit-testing jasmine

Answer 1

Answer №1

When working with files, it's important to note that you cannot access variables from other files or mock imports. Dependency injection (DI) becomes your best ally in these situations, allowing you to provide a mock class for testing purposes.

In order to test services that retrieve data, you'll need to create mocks instead of relying on separate files. One approach is to export JSON or objects and utilize the exported data.

TestBed.configureTestingModule({
    imports: [
    ],
    declarations: [
        ComponentDetailsComponent,
    ],
    providers: [
        {
            provide: RealService,
            useExisting: StubService,
        },
    ],
}).compileComponents();

To implement the stub, follow this example:

class StubService implements Partial<RealService> {
    getuserInfo() {
        return { ...mockedData };
    }
}

Additionally, when dealing with mocking HTTP calls, make sure to use HttpTestingController.

Answer 2

When working with files, it's important to note that you cannot access variables from other files or mock imports. Dependency injection (DI) becomes your best ally in these situations, allowing you to provide a mock class for testing purposes.

In order to test services that retrieve data, you'll need to create mocks instead of relying on separate files. One approach is to export JSON or objects and utilize the exported data.

TestBed.configureTestingModule({
    imports: [
    ],
    declarations: [
        ComponentDetailsComponent,
    ],
    providers: [
        {
            provide: RealService,
            useExisting: StubService,
        },
    ],
}).compileComponents();

To implement the stub, follow this example:

class StubService implements Partial<RealService> {
    getuserInfo() {
        return { ...mockedData };
    }
}

Additionally, when dealing with mocking HTTP calls, make sure to use HttpTestingController.

What is the best way to simulate global variables that are declared in a separate file?

Answer №1

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