Angular 7 Test: NullInjectorError: No provider for ActivatedRoute

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05-09-2024

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Debugging the "NullInjectorError: No provider for ActivatedRoute" in Angular 7 Tests

This article addresses a common error encountered while testing Angular 7 components: "NullInjectorError: No provider for ActivatedRoute". We'll analyze the error, explore solutions based on Stack Overflow insights, and provide practical examples for robust testing.

Understanding the Error

The NullInjectorError: No provider for ActivatedRoute indicates that your Angular test environment cannot find a provider for the ActivatedRoute service, a crucial component for routing in Angular applications. This usually occurs because the ActivatedRoute is typically provided by the Angular Router, and it's not automatically available in your unit tests.

Stack Overflow Insights

Here's how we can leverage insights from Stack Overflow to address this:

1. Importing RouterTestingModule:

Stack Overflow Source: https://stackoverflow.com/questions/48716419/angular-4-routertesingmodule-doesnt-provide-activatedroute-in-tests

The RouterTestingModule is a testing module specifically designed to provide mocked routing services, including ActivatedRoute, making it essential for your tests.

Example:

import { RouterTestingModule } from '@angular/router/testing';

TestBed.configureTestingModule({
  imports: [
    RouterTestingModule,
    HttpClientTestingModule // existing imports
  ],
  declarations: [ BeerDetailsComponent ]
});

2. Providing ActivatedRoute in the Test Module:

Stack Overflow Source: https://stackoverflow.com/questions/53030456/angular-testing-with-routertesingmodule-gives-nullinjectorerror

If you need more granular control, you can explicitly provide a mock ActivatedRoute within your test module.

Example:

import { ActivatedRoute } from '@angular/router';

TestBed.configureTestingModule({
  // ... other imports
  providers: [
    { provide: ActivatedRoute, useValue: { snapshot: { data: { } } } },
  ]
});

3. Mocked Route Configuration:

Stack Overflow Source: https://stackoverflow.com/questions/49988055/angular-unit-testing-error-nullinjectorerror-no-provider-for-activatedroute

Ensure your RouterTestingModule is correctly configured to handle routes relevant to your component.

Example:

import { RouterTestingModule } from '@angular/router/testing';

TestBed.configureTestingModule({
  imports: [
    RouterTestingModule.withRoutes([
      // Define your component's route path here, e.g.,
      { path: 'beer/:id', component: BeerDetailsComponent }
    ]),
    HttpClientTestingModule // existing imports
  ],
  declarations: [ BeerDetailsComponent ]
});

Practical Application:

To demonstrate the solution, let's take your original BeerDetailsComponent example and apply the corrections:

import { async, ComponentFixture, TestBed, inject } from '@angular/core/testing';
import { BeerDetailsComponent } from './beer-details.component';
import { HttpClientTestingModule } from '@angular/common/http/testing';
import { RouterTestingModule } from '@angular/router/testing'; // Import RouterTestingModule

describe('BeerDetailsComponent', () => {
  let component: BeerDetailsComponent;
  let fixture: ComponentFixture<BeerDetailsComponent>;

  beforeEach(async(() => {
    TestBed.configureTestingModule({
      imports: [
        HttpClientTestingModule, 
        RouterTestingModule.withRoutes([ // Configure routes
          { path: 'beer/:id', component: BeerDetailsComponent }
        ])
      ],
      declarations: [ BeerDetailsComponent ]
    })
    .compileComponents();
  }));

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

  it('should create',
  inject(
    [HttpTestingController],
    () => {
      expect(component).toBeTruthy();
    }
  )
)
});

Adding Value Beyond Stack Overflow:

In addition to the solutions, here are additional points to consider:

• Mocking Route Data: You can further customize the behavior of ActivatedRoute in your tests by providing mock route data. This allows you to control the information passed to your component.
• Testing Router Navigation: While this error focuses on the ActivatedRoute, it's important to remember that the RouterTestingModule provides a full suite of tools for testing router navigation within your components.
• Angular Router Documentation: For a deeper understanding of the Angular Router, its features, and testing best practices, refer to the official Angular documentation: https://angular.io/guide/router

By combining insights from Stack Overflow with a thorough understanding of Angular testing and routing, you can confidently debug and resolve the "NullInjectorError: No provider for ActivatedRoute" and ensure your components are well-tested.