A guide to simulating ngControl in a Custom Form Control for effective unit testing in Angular

Question

A guide to simulating ngControl in a Custom Form Control for effective unit testing in Angular

I need some guidance on creating unit tests for a Custom Form Control in Angular 9. The issue arises with this line of code:

constructor(@Self() private ngControl: NgControl)

, which triggers an error:

Error: NodeInjector: NOT_FOUND [NgControl]

. It seems that I must set a value accessor somehow.

I have injected ngControl in the constructor because I will be using it later in my component. This is why I did not opt for the typical implementation with provide: NG_VALUE_ACCESSOR.

I attempted to mock it like so:

beforeEach(async(() => {
    TestBed.configureTestingModule({
        providers: [
            { provide: NgControl, useValue: new FormControlDirective([], [], [], null) }
        ],
        imports: [FormsModule, ReactiveFormsModule]
    }).compileComponents();

However, I encountered the following error:

No valid value accessor for form control with unspecified name attribute

since I am unsure of what should go under the 3rd parameter of the function FormControlDirective, which is:

valueAccessors: ControlValueAccessor[]

Can anyone offer insights on how to properly mock this scenario?

angular typescript mocha.js angular-test

Answer 1

Answer №1

One way to mock it is by following this example:

let ngControlMock: any;

beforeEach(async(() => {
    ngControlMock = jasmine.createSpyObj('ngControl', ['value', /* add other necessary methods here */]);
    TestBed.configureTestingModule({
        providers: [
            { provide: NgControl, useValue: ngControlMock }
        ],
        imports: [FormsModule, ReactiveFormsModule]
    }).compileComponents();

Answer 2

One way to mock it is by following this example:

let ngControlMock: any;

beforeEach(async(() => {
    ngControlMock = jasmine.createSpyObj('ngControl', ['value', /* add other necessary methods here */]);
    TestBed.configureTestingModule({
        providers: [
            { provide: NgControl, useValue: ngControlMock }
        ],
        imports: [FormsModule, ReactiveFormsModule]
    }).compileComponents();

Answer 3

Answer №2

I encountered an issue where my Module with CustomFormControl was not functioning properly due to my failure to include it in the Imports array. By rectifying this oversight, I was able to resolve the problem. Perhaps this solution can benefit someone else facing a similar issue.

Answer 4

I encountered an issue where my Module with CustomFormControl was not functioning properly due to my failure to include it in the Imports array. By rectifying this oversight, I was able to resolve the problem. Perhaps this solution can benefit someone else facing a similar issue.

A guide to simulating ngControl in a Custom Form Control for effective unit testing in Angular

Answer №1

Answer №2

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