Testing routing and navigation in Angular

Introduction

Testing routing and navigation helps make sure your app moves between pages correctly. It checks if users reach the right screens when they click links or buttons.

When you want to confirm a button click sends users to the correct page.

When you add new routes and want to verify they work as expected.

When you fix navigation bugs and want to prevent them from coming back.

When you want to check that URL changes load the right components.

When you want to test route guards that control access to pages.

Syntax

Angular

import { TestBed } from '@angular/core/testing';
import { RouterTestingModule } from '@angular/router/testing';
import { Router } from '@angular/router';
import { Location } from '@angular/common';

const routes = [
  { path: 'path', component: YourComponent }
];

TestBed.configureTestingModule({
  imports: [RouterTestingModule.withRoutes(routes)],
  declarations: [YourComponent]
});

const router = TestBed.inject(Router);
const location = TestBed.inject(Location);

router.navigate(['/path']);
expect(location.path()).toBe('/path');

Use RouterTestingModule to simulate routing in tests without a real browser.

Inject Router and Location to control and check navigation.

Examples

Navigate to the '/home' route and check if the URL path updates correctly.

Angular

router.navigate(['/home']);
expect(location.path()).toBe('/home');

Use navigateByUrl to go to '/about' and verify the path.

Angular

router.navigateByUrl('/about');
expect(location.path()).toBe('/about');

Navigate to a route with a parameter and check the full path.

Angular

router.navigate(['/user', 42]);
expect(location.path()).toBe('/user/42');

Sample Program

This test setup creates two simple pages: Home and About. It uses Angular's RouterTestingModule to simulate navigation. The tests check if navigating to '/home' and '/about' updates the URL path correctly.

Angular

import { Component } from '@angular/core';
import { TestBed, fakeAsync, tick } from '@angular/core/testing';
import { RouterTestingModule } from '@angular/router/testing';
import { Router, Routes } from '@angular/router';
import { Location } from '@angular/common';

@Component({ selector: 'app-home', template: '<h1>Home</h1>' })
class HomeComponent {}

@Component({ selector: 'app-about', template: '<h1>About</h1>' })
class AboutComponent {}

const routes: Routes = [
  { path: 'home', component: HomeComponent },
  { path: 'about', component: AboutComponent }
];

describe('Router navigation test', () => {
  let router: Router;
  let location: Location;

  beforeEach(() => {
    TestBed.configureTestingModule({
      imports: [RouterTestingModule.withRoutes(routes)],
      declarations: [HomeComponent, AboutComponent]
    });

    router = TestBed.inject(Router);
    location = TestBed.inject(Location);

    router.initialNavigation();
  });

  it('should navigate to /home', fakeAsync(() => {
    router.navigate(['/home']);
    tick();
    expect(location.path()).toBe('/home');
  }));

  it('should navigate to /about', fakeAsync(() => {
    router.navigateByUrl('/about');
    tick();
    expect(location.path()).toBe('/about');
  }));
});

Important Notes

Use fakeAsync and tick() to handle asynchronous navigation in tests.

Always import RouterTestingModule with your app routes for realistic routing tests.

Check location.path() to verify the current URL after navigation.

Summary

Testing routing ensures users reach the right pages.

Use RouterTestingModule to simulate routes in tests.

Check navigation results by inspecting the URL path with Location.

Practice

1. What is the main purpose of using RouterTestingModule in Angular tests?

easy

A. To style the router links in the application

B. To disable routing completely in tests

C. To create real HTTP requests during navigation

D. To simulate routing behavior without starting the full app

Solution

1. Step 1: Understand the role of RouterTestingModule

   RouterTestingModule is designed to simulate routing in tests without launching the full Angular app.

2. Step 2: Compare options with this purpose

   Styling the router links is incorrect. Creating real HTTP requests during navigation is wrong. Disabling routing completely is incorrect. Simulating routing behavior without starting the full app correctly describes this testing utility.

3. Final Answer:

   To simulate routing behavior without starting the full app -> Option D

4. Quick Check:

   RouterTestingModule simulates routing [OK]

Hint: RouterTestingModule simulates routes in tests, not real navigation [OK]

Common Mistakes:

• Thinking RouterTestingModule styles links
• Assuming it sends real HTTP requests
• Believing it disables routing

2. Which of the following is the correct way to import RouterTestingModule in an Angular test file?

easy

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

B. import { RouterTestingModule } from '@angular/core/testing';

C. import { RouterTestingModule } from '@angular/router';

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

Solution

1. Step 1: Recall the correct import path

   The RouterTestingModule is provided by the '@angular/router/testing' package.

2. Step 2: Verify each option's path

   Only import { RouterTestingModule } from '@angular/router/testing'; uses the correct path '@angular/router/testing'. Others are incorrect or do not exist.

3. Final Answer:

   import { RouterTestingModule } from '@angular/router/testing'; -> Option A

4. Quick Check:

   Correct import path is '@angular/router/testing' [OK]

Hint: RouterTestingModule always imports from '@angular/router/testing' [OK]

Common Mistakes:

• Importing from '@angular/core/testing'
• Importing from '@angular/router'
• Using a non-existent path

3. Given this test snippet, what will location.path() return after navigation?

const fixture = TestBed.createComponent(AppComponent);
const router = TestBed.inject(Router);
const location = TestBed.inject(Location);
router.navigate(['/dashboard']);
fixture.detectChanges();
await fixture.whenStable();
console.log(location.path());

medium

A. "/"

B. "/dashboard"

C. "/home"

D. "undefined"

Solution

1. Step 1: Understand navigation and location.path()

   Calling router.navigate(['/dashboard']) changes the URL path to '/dashboard'. The Location service reflects this path.

2. Step 2: Confirm location.path() after navigation

   After navigation and stabilization, location.path() returns the current URL path, which is '/dashboard'.

3. Final Answer:

   "/dashboard" -> Option B

4. Quick Check:

   location.path() shows current URL path [OK]

Hint: location.path() returns the current URL after navigation [OK]

Common Mistakes:

• Expecting location.path() to be '/' by default
• Confusing location.path() with component state
• Not awaiting navigation completion

4. Identify the error in this test setup for routing:

beforeEach(() => {
  TestBed.configureTestingModule({
    imports: [RouterTestingModule],
    declarations: [AppComponent]
  });
  router = TestBed.inject(Router);
  location = TestBed.inject(Location);
  fixture = TestBed.createComponent(AppComponent);
  router.navigate(['/profile']);
  fixture.detectChanges();
});

medium

A. router.navigate() must be called after fixture.detectChanges()

B. RouterTestingModule should not be imported in tests

C. Missing call to compileComponents() before creating the component

D. Location service cannot be injected in tests

Solution

1. Step 1: Check Angular test setup best practices

   When using TestBed with components, compileComponents() must be called to compile templates before creating components.

2. Step 2: Analyze the given code

   The code configures the module but does not call compileComponents(), which can cause errors when creating the component.

3. Final Answer:

   Missing call to compileComponents() before creating the component -> Option C

4. Quick Check:

   Always call compileComponents() before createComponent() [OK]

Hint: Always call compileComponents() before createComponent() in tests [OK]

Common Mistakes:

• Skipping compileComponents() causes template errors
• Thinking RouterTestingModule is not needed
• Calling navigate() before detectChanges() is allowed

5. You want to test that navigating to /settings loads the SettingsComponent. Which approach correctly tests this behavior?

hard

A. Use RouterTestingModule with routes, navigate to '/settings', then check if the component instance is of type SettingsComponent

B. Manually create SettingsComponent and call its ngOnInit without routing

C. Use RouterTestingModule but do not define routes, then navigate to '/settings'

D. Navigate to '/settings' without RouterTestingModule and check the URL

Solution

1. Step 1: Set up RouterTestingModule with route definitions

   To test navigation, RouterTestingModule must be configured with routes linking '/settings' to SettingsComponent.

2. Step 2: Navigate to '/settings' and verify component

   After navigation, verify the loaded component instance is SettingsComponent to confirm correct routing.

3. Final Answer:

   Use RouterTestingModule with routes, navigate to '/settings', then check if the component instance is of type SettingsComponent -> Option A

4. Quick Check:

   Define routes and check component after navigation [OK]

Hint: Define routes in RouterTestingModule to test navigation and component loading [OK]

Common Mistakes:

• Not defining routes in RouterTestingModule
• Testing component without routing
• Checking URL without verifying component