Angular 5 Unit testing throwing error for "components should create " test case

Question

I am trying Angular 5 unit testing for the first time. While I already created the app then decided to run testing in it. But I am getting these errors:

AppComponent should create the app
AppComponent should have as title 'app'
AppComponent should render title in a h1 tag
GalleryComponent should create
UploadComponent should create

and error details like :

Failed: Template parse errors:
'app-upload' is not a known element:
1. If 'app-upload' is an Angular component, then verify that it is part of this module.
2. If 'app-upload' is a Web Component then add 'CUSTOM_ELEMENTS_SCHEMA' to the '@NgModule.schemas' of this component to suppress this message. (" class="row">
        <div class="col-md-3" style="padding:5%; box-sizing: border-box">
            [ERROR ->]<app-upload></app-upload>
        </div>
        <div class="col-md-9">
"): ng:///DynamicTestModule/AppComponent.html@3:12

My package.json dev dependencies :

devDependencies": {
    "@angular/compiler-cli": "^6.0.2",
    "@angular-devkit/build-angular": "~0.6.3",
    "typescript": "~2.7.2",
    "@angular/cli": "~6.0.3",
    "@angular/language-service": "^6.0.2",
    "@types/jasmine": "2.8.6",
    "@types/jasminewd2": "~2.0.3",
    "@types/node": "~8.9.4",
    "codelyzer": "~4.2.1",
    "jasmine-core": "~2.99.1",
    "jasmine-spec-reporter": "~4.2.1",
    "karma": "~1.7.1",
    "karma-chrome-launcher": "~2.2.0",
    "karma-coverage-istanbul-reporter": "~1.4.2",
    "karma-jasmine": "~1.1.1",
    "karma-jasmine-html-reporter": "^0.2.2",
    "protractor": "~5.3.0",
    "ts-node": "~5.0.1",
    "tslint": "~5.9.1"
  } 

Test file app.component.spec.ts

import { TestBed, async } from '@angular/core/testing';
import { AppComponent } from './app.component';
describe('AppComponent', () => {
  beforeEach(async(() => {
    TestBed.configureTestingModule({
      declarations: [
        AppComponent
      ],
    }).compileComponents();
  }));
  it('should create the app', async(() => {
    const fixture = TestBed.createComponent(AppComponent);
    const app = fixture.debugElement.componentInstance;
    expect(app).toBeTruthy();
  }));
  it(`should have as title 'app'`, async(() => {
    const fixture = TestBed.createComponent(AppComponent);
    const app = fixture.debugElement.componentInstance;
    expect(app.title).toEqual('app');
  }));
  it('should render title in a h1 tag', async(() => {
    const fixture = TestBed.createComponent(AppComponent);
    fixture.detectChanges();
    const compiled = fixture.debugElement.nativeElement;
    expect(compiled.querySelector('h1').textContent).toContain('Welcome to Typito-photo-app!');
  }));
});

I couldn't figure out how to solve these. I haven't made any changes in spec files nor did I wrote any test cases. Shouldn't all these be running as expected according to what is described in angular documentation?

Answer 1

The component that you want to test has one or more child components. A good practice is to ignore these component and test these separate.

A way to archieve this is to tell your angular Testbed to skip these during the component building using NO_ERRORS_SCHEMA inside your Testbed.

import { NO_ERRORS_SCHEMA } from '@angular/core';

Then your Testbed should look like this:

TestBed.configureTestingModule({
            declarations: [
                AppComponent
            ],
            schemas: [
                NO_ERRORS_SCHEMA
            ]
        }).compileComponents();

And it should ignore all custom elements(tags) that appears in your component.html.

Another way is to mock your child components. e.g like this

Answer 2

You should verify component to be available:

 beforeEach(() => {
    fixture = TestBed.createComponent(AppComponent);
    component = fixture.componentInstance;
});

it('should be created', () => {
    fixture.detectChanges();
    expect(component)
        .toBeTruthy();
});

Also you should inject any dependencies in the test Module while writing tests.