What is causing the reluctance of my Angular test to accept my custom form validation function?

Question

What is causing the reluctance of my Angular test to accept my custom form validation function?

I'm currently facing an issue with testing an angular component called "FooComponent" using Karma/Jasmine.

Snippet of code from foo.component.spec.ts file:

describe('FooComponent', () => {
    let component: FooComponent
    let fixture: ComponentFixture<FooComponent>
    let componentElement: DebugElement
    let bar: FormControl

...

beforeEach(() => {
    fixture = TestBed.createComponent(FooComponent)
    component = fixture.componentInstance
    fixture.detectChanges()
    component.ngOnInit()
    componentElement = fixture.debugElement
    bar = component.bar
  })

it('should create the FooComponent', () => {
    expect(component).toBeTruthy()
})

Encountering this error while running ng test:

Chrome 63.0.3239 (Windows 10 0.0.0) FooComponent should create the 
FooComponent FAILED

    TypeError: Cannot read property 'validate' of undefined
        at normalizeValidator .../node_modules/@angular/forms/esm5/forms.js:1059:23)
        at Array.map (<anonymous>)
        at composeValidators .../node_modules/@angular/forms/esm5/forms.js:2422:1)
        at coerceToValidator .../node_modules/@angular/forms/esm5/forms.js:2826:1)
        at new FormControl .../node_modules/@angular/forms/esm5/forms.js:3881:1)
        at FooComponent.webpackJsonp.../../../../../src/app/foo/foo.component.ts.FooComponent.createFormControls ....../src/app/foo/foo.component.ts:43:16)
        at FooComponent.webpackJsonp.../../../../../src/app/foo/foo.component.ts.FooComponent.ngOnInit ....../src/app/foo/foo.component.ts:37:10)
        at checkAndUpdateDirectiveInline .../node_modules/@angular/core/esm5/core.js:12400:1)
        at checkAndUpdateNodeInline .../node_modules/@angular/core/esm5/core.js:13927:1)
        at checkAndUpdateNode .../node_modules/@angular/core/esm5/core.js:13870:1)

The issue seems to be related to lines 37 and 43 in foo.component.ts:

ngOnInit() {
    //this is line 37
    this.createFormControls()
    this.createForm()
}

createFormControls() {
    //this is line 43
    this.bar = new FormControl('', [Validators.required, this.fooService.validateBar])
}

createForm() {
    this.fooForm = new FormGroup({
        bar: this.bar
    })
}

It appears that there might be a problem with the custom validation function implemented in FooService (which is injected into FooComponent). Below is the validation function defined in foo.service.ts:

validateBar(bar: FormControl) {
    return bar.value.length == 10 ? null : { invalidBar: true }
}

Any suggestions on how to resolve this?

javascript angular typescript jasmine karma-runner

Answer 1

Answer №1

It appears that in your beforeEach function, you are calling component.ngOnInit() directly.

beforeEach(() => {
    ...
    component.ngOnInit()
    ...
});

Instead of directly invoking ngOnInit(), the method is meant to be called by the test runner using:

fixture.detectChanges()

For more information on this behavior, please check out the documentation: https://angular.io/guide/testing

Answer 2

It appears that in your beforeEach function, you are calling component.ngOnInit() directly.

beforeEach(() => {
    ...
    component.ngOnInit()
    ...
});

Instead of directly invoking ngOnInit(), the method is meant to be called by the test runner using:

fixture.detectChanges()

For more information on this behavior, please check out the documentation: https://angular.io/guide/testing

Answer 3

Answer №2

Encountering "cannot read property 'validate' of undefined" errors can be quite frustrating, especially when there is limited information available on how to resolve them.

The issue typically arises when the formGroup is undefined, but the HTML code is attempting to render and validate formGroup.valid (such as enabling a submit button).

Usually, creating a mock FormBuilder(), defining the FormGroup, constructing a data object that the reusable component requires, and then supplying it to the component solves the problem. However, there are instances where this approach may not work.

To address this, consider adding an ngIf statement to ensure that the controls are initialized before the component renders:

<form class="form-popup" *ngIf="formGroup && formGroup.controls.length" [formGroup]="formGroup"></form"

This issue commonly occurs when a component utilizes a reusable component for aesthetics and injects the formGroup data during ngOnInit. In such cases, the data might not be readily available, leading to rendering issues.

<ng-template *ngComponentOutlet="component;injector:injector"></ng-template">

In scenarios like these, simply calling fixture.detectChanges() may not be sufficient for rendering the component correctly.

Answer 4

Encountering "cannot read property 'validate' of undefined" errors can be quite frustrating, especially when there is limited information available on how to resolve them.

The issue typically arises when the formGroup is undefined, but the HTML code is attempting to render and validate formGroup.valid (such as enabling a submit button).

Usually, creating a mock FormBuilder(), defining the FormGroup, constructing a data object that the reusable component requires, and then supplying it to the component solves the problem. However, there are instances where this approach may not work.

To address this, consider adding an ngIf statement to ensure that the controls are initialized before the component renders:

<form class="form-popup" *ngIf="formGroup && formGroup.controls.length" [formGroup]="formGroup"></form"

This issue commonly occurs when a component utilizes a reusable component for aesthetics and injects the formGroup data during ngOnInit. In such cases, the data might not be readily available, leading to rendering issues.

<ng-template *ngComponentOutlet="component;injector:injector"></ng-template">

In scenarios like these, simply calling fixture.detectChanges() may not be sufficient for rendering the component correctly.

What is causing the reluctance of my Angular test to accept my custom form validation function?

Answer №1

Answer №2

Similar questions

Remove a file using Mongoose and Express by simply pressing a button

Pass an image into an input field with the attribute type="filename" using JavaScript directly

Puppeteer throwing an error when querying selectors cannot be done (TypeError: selector.startsWith is not a supported function)

Direct user to an external webpage with Vue 3

Is it possible to employ variable data outside the function?

The WebView.HitTestResult method is currently only receiving <img src> elements and not <a href> elements

Having trouble with localstorage.setitem function in Angular?

What is the best way to create a selection input using buttons and save the chosen option in the state?

Navigating through hidden input fields in Angular by utilizing the tab key

What is the best way to prevent the body from scrolling when scrolling on a fixed div without making the body's scroll bar disappear?

Dynamic shopping cart with Vue.js

Opening an external link from the Side Menu in Ionic4: A step-by-step guide

Ways to transfer a function as attributes from one functional element to another?

Toggle visibility of div based on current business hours, incorporating UTC time

Mouse click failing to trigger CSS property update

I'm new to Angular, so could you please explain this to me? I'm trying to understand the concept of `private todoItems: TodoItem[] = []`. I know `TodoItem` is an array that

"Troubleshooting: NuxtJs vue-flip feature stuck on front side, not rotating to

Tips on adjusting the hover color in the data grid

Setting up Spectron

Using Vue.js, execute a function when there is input, but with a slight delay