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This is my function,

downloadPdf(event: any) {
    if (event.url) {
      const file = new Blob([event.url], {type: 'text/plain'});
      FileSaver.saveAs(file,'receipt.pdf');
    } else {
      this.alertService.showAlert(AlertType.ERROR, "Receipt URL not Found!");
      throw new Error();
    }
  }

This is the HTML code for the button,

<ng-template pTemplate="body" let-record>
              <tr>
                <td *ngFor="let column of  tableColumns">
                  <div>
                    <button pButton
                            type="button"
                            label="Download"
                            class="p-button-raised p-button-success"
                            (click)="downloadPdf(record)"
                    >
                    </button>
                  </div>
                </td>
              </tr>
            </ng-template>

The record contains the byte array and some other details. This is the unit test I have written,

it('downloadPdf when no url present', () => {
    const event = {
      url: null
    }
    component.downloadPdf(event);
    expect(alertServiceMock.showAlert).toHaveBeenCalled();
  });

I receive a byte array in the URL attribute and the code is working fine. When I run the unit test for the else condition it fails.

Error thrown
    Error: 
        at BalanceReportComponent../src/app/widgets/balance-report/balancereport.component.ts.BalanceReportComponent.downloadPdf (http://localhost:9876/_karma_webpack_/src/app/widgets/balance-report/balance-report.component.ts:174:13)
        at UserContext.<anonymous> (http://localhost:9876/_karma_webpack_/src/app/widgets/balance-report/balance-report.component.spec.ts:205:15)
        at ZoneDelegate../node_modules/zone.js/dist/zone.js.ZoneDelegate.invoke (http://localhost:9876/_karma_webpack_/node_modules/zone.js/dist/zone.js:386:1)
        at ProxyZoneSpec.push../node_modules/zone.js/dist/zone-testing.js.ProxyZoneSpec.onInvoke (http://localhost:9876/_karma_webpack_/node_modules/zone.js/dist/zone-testing.js:292:1)
        at ZoneDelegate../node_modules/zone.js/dist/zone.js.ZoneDelegate.invoke (http://localhost:9876/_karma_webpack_/node_modules/zone.js/dist/zone.js:385:1)
        at Zone../node_modules/zone.js/dist/zone.js.Zone.run (http://localhost:9876/_karma_webpack_/node_modules/zone.js/dist/zone.js:143:1)
        at runInTestZone (http://localhost:9876/_karma_webpack_/node_modules/zone.js/dist/zone-testing.js:545:1)
        at UserContext.<anonymous> (http://localhost:9876/_karma_webpack_/node_modules/zone.js/dist/zone-testing.js:560:1)
        at <Jasmine>

How should I write a proper unit test for the second condition in my function?

Giannis
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Akila Ekanayake
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  • Does this answer your question? [How to write a test which expects an Error to be thrown in Jasmine?](https://stackoverflow.com/questions/4144686/how-to-write-a-test-which-expects-an-error-to-be-thrown-in-jasmine) – Julien Jun 28 '21 at 07:13
  • Sorry no. But thanks anyway. Actually, my concern is why the null value is not recognized and jump into else part? or if jumped why is there an error. Previous tests work fine. This is the first only time I've used FileSaver. – Akila Ekanayake Jun 30 '21 at 09:40

0 Answers0