Forms array error while unit test using jasmine and karma

Question

I'am writing unit test case for angular application version 9. but im getting below error.

TypeError: Cannot read property 'get' of undefined

how to spy getFormControls methos or else i have to use spyonproperty, i have tried to set spyonproperty but getting different error.

iam new to jasmine unit test getting struck in most of place,

ts:

  get getFormControls() {
    const control = this.relTable.get('tableRows') as FormArray;
    return control;
  }

submit() {
    this.messageService.clear();

/*     const formGroup = this.getFormControls.controls[this.isEdit.length - 1] as FormGroup;
    const rNameValue = formGroup.controls['rName'].value;
    const pEntityValue = formGroup.controls['pEntity'].value;
    const cEntityValue = formGroup.controls['cEntity'].value;


    this.new_rel_Data.push({
      'rName': rNameValue,
      'pEntity': pEntityValue,
      'cEntity': cEntityValue
    });  */



     this.new_rel_Data.push({
      'rName': this.getFormControls.controls[this.isEdit.length - 1].get('rName').value,
      'pEntity': this.getFormControls.controls[this.isEdit.length - 1].get('pEntity').value,
      'cEntity': this.getFormControls.controls[this.isEdit.length - 1].get('cEntity').value
    }); 

    this.relTemp.addReldata(this.new_rel_Data).subscribe(
      (res) => {
        console.log(res);
        this.loadRelTemp();
        this.messageService.add({ severity: 'success', summary: 'New value inserted successfully', sticky: true });
      },
      (err) => {
        this.messageService.add({ severity: 'error', summary: err.message, detail: 'Please contact Admin', sticky: true });
      },
      () => {
        const control = this.relTable.get('tableRows') as FormArray;
        control.clear();
        this.enableSubmit = false;
      }
    );

  }

spec:

 // submit for insert new value
  fit('Submit() Relational data', () => {

    let data = [ 'foo' ];
    component.new_rel_Data = data;

  fixture.detectChanges();
    spyOn(component, 'submit').and.callThrough();
    

    spyOn(relTemplateUpdateService, 'addReldata').and.returnValue(
      of({ result: { status: 200 } })
    );
    component.submit();
    fixture.detectChanges();
    expect(component.submit).toHaveBeenCalled();
    expect(relTemplateUpdateService.addReldata).toHaveBeenCalledWith(data);
  });

Gynteniuxas · Accepted Answer · 2020-10-04 10:05:57Z

1

When you have errors like these: TypeError: Cannot read property 'get' of undefined, usually that means you forgot to add/mock something in your tests (although this could happen anywhere in real code as well).

In this particular case, you missed to mock either relTable or the result of getFormControls getter.

In any case, I would probably mock the getter like this:

spyOnProperty(relTemplateUpdateService, 'getFormControls').and.returnValue(new FormArray([
    new FormGroup({
      rName: new FormControl('rName'),
      pEntity: new FormControl('pEntity'),
      cEntity: new FormControl('cEntity'),
    }),
  ]));

Since TypeScript doesn't allow assigning to a getter, you would probably need to use spyOnProperty method instead of something like relTemplateUpdateService.getFormControls = .... If it wasn't a getter, then you could have also mocked this.relTable with the same return value but I personally didn't find this working with getter.

Also you should check (probably better in real code; unless you're sure you don't need to) that this.isEdit is always greater than 0, otherwise, you'll get another error with undefined.

answered Oct 4, 2020 at 10:05

Gynteniuxas

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2 Comments

Gopinath Vedagiri Over a year ago

still getting same error and i have change relTemplateUpadteService to component like below because getFormControls is a method which inside component. spyOnProperty(component, 'getFormControls').and.returnValue(new FormArray([ new FormGroup({ rName: new FormControl('rName'), pEntity: new FormControl('pEntity'),

Gynteniuxas Over a year ago

You might need to share more details (code) since for me it looks to be working. It could be a totally different area.

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