Jasmine is raising an error: "TypeError: Unable to access the property 'client' of an undefined object"

While running test cases for the EditFlag component in Angular, I encountered an error stating TypeError: Cannot read property 'client' of undefined. Additionally, I am looking to add a test case for a switch case function. Can someone assist me with this particular test case?

editflag.component.ts

constructor(private flagService: FlagService,
private editFlagDialog: MatDialogRef<EditFlagComponent>),
@Inject(MAT_DIALOG_DATA) public data: any,
private dialog: MatDialog){}

ngOnInit: void {
    switch(this.data.action) {
        case 'create':
            this.flagClone = this.initializeFlagClone();
            break;
        case 'edit':
            this.flagEdit();
            break;
        default:
            console.log('No action');
    }
}

public flagEdit(){
    const res = {...this.data};
    this.flagVar = { ...res.flag};
    if(this.data.flag.client == null ) {
        this.isSearch = false;
        this.initializeClient();
    }
}

editflag.spec.ts

const testData = {
    "flag":{
        id: null, //string
        description: null,  //string
        url: null,      //string
        client: null
    },
    "action": "edit"
};

beforeEach(async(() => {
    TestBed.configureTestingModule({
      imports: [
        RouterTestingModule
      ],
      declarations: [
        EditFlagComponent
      ],
      providers: [
        HttpClient,
        HttpHandler,
        {provide: MatDialog, useValue: {} },
        {provide: MatDialogRef, useValue: {} },
        {provide: MAT_DIALOG_DATA, useValue: {testData} },
      ]
    }).compileComponents();
  }));

  beforeEach(() => {
    fixture = TestBed.createComponent(EditFlagComponent);
    component = fixture.componentInstance;
    fixture.detectChanges();
  });
  
it('should call flagEdit',() => {
    component.flag.client = testData.flag.client;
    component.flagEdit();
    fixture.detectChanges();
    expect(component.isSearch).tobeFalsy();
});

I also hope that the transition block mentioned below will be covered in the summary:

switch(this.data.action) {
        case 'create':
            this.flagClone = this.initializeFlagClone();
            break;
        case 'edit':
            this.flagEdit();
            break;
        default:
            console.log('No action');
    }

Answer №1

It seems like there is a mistake in your usage of useValue.

Please update this line:

{provide: MAT_DIALOG_DATA, useValue: {testData} },

to the following:

{provide: MAT_DIALOG_DATA, useValue: testData },

Additionally, make sure to remove the line

component.flag.client = testData.flag.client;

from your unit test.

Answer №2

An issue has arisen with the message TypeError: Cannot read property 'client' of undefined. This error occurs at the line this.data.flag.client == null

You have specified

@Inject(MAT_DIALOG_DATA) public data: any,
and in your test, you are using
{provide: MAT_DIALOG_DATA, useValue: {testData} },
This is similar to having {provide: MAT_DIALOG_DATA, useValue: {testData: testData} },` i.e

this.data = { testData: {
    "flag":{
        id: null, //string
        description: null,  //string
        url: null,      //string
        client: null
    },
    "action": "edit"
}}

The issue lies in the fact that you haven't assigned a value to this.data.flag

To rectify this, simply change

{provide: MAT_DIALOG_DATA, useValue: {testData} },
to
{provide: MAT_DIALOG_DATA, useValue: testData },
and then you will be supplying the value correctly

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