Common Angular Testing Errors and Fixes

This document outlines common errors encountered during Angular application testing and their corresponding fixes. It provides solutions for resolving dependency injection issues, mocking services, and configuring the testing module to ensure smooth test execution.

Error:

NullInjectorError: R3InjectorError(DynamicTestModule)[FormBuilder -> FormBuilder]:
NullInjectorError: No provider for FormBuilder!

Fix:

import { ReactiveFormsModule } from '@angular/forms';

imports: [ReactiveFormsModule], // Add this

Error:

HeadlessChrome 78.0.3882 (Windows 10.0.0) CustomeDateRangeComponent should create FAILED
NullInjectorError: R3InjectorError(DynamicTestModule)[Router -> Router]:
NullInjectorError: No provider for Router!

Fix:

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

// Add below in configureTestingModule
imports: [RouterTestingModule],

Error:

HeadlessChrome 78.0.3882 (Windows 10.0.0) ExportPopupComponent should create FAILED
NullInjectorError: R3InjectorError(DynamicTestModule)[MatDialogRef -> MatDialogRef]:
NullInjectorError: No provider for MatDialogRef!

Fix:

import { MatDialogRef, MAT_DIALOG_DATA } from '@angular/material/dialog';

// Add provider in configureTestingModule
providers: [
  { provide: MatDialogRef, useValue: {} }, // Mock MatDialogRef
  { provide: MAT_DIALOG_DATA, useValue: {} } // Mock MAT_DIALOG_DATA
]

Error:

NullInjectorError: R3InjectorError(DynamicTestModule)[ChannelsService -> ApiService -> HttpClient -> HttpClient]:
NullInjectorError: No provider for HttpClient!

Fix:

import { HttpClientModule } from '@angular/common/http';

beforeEach(() => {
  TestBed.configureTestingModule({
    imports: [HttpClientModule], // Add this
  });
});

Error:

NullInjectorError: R3InjectorError(DynamicTestModule)[ToastNotificationsService -> MatSnackBar -> MatSnackBar]:
NullInjectorError: No provider for MatSnackBar!

Fix:

// Add below in import
imports: [MatSnackBarModule],

Error:

NullInjectorError: R3InjectorError(DynamicTestModule)[MatDialog -> MatDialog]:
NullInjectorError: No provider for MatDialog!

Fix:

imports: [MatDialogModule],

Error:

TypeError: Cannot read property 'loader' of undefined

Fix:

// Add in beforeEach after component initialization
component.tableWidget = {
  loader: false,
};

Error:

NullInjectorError: R3InjectorError(DynamicTestModule)[Store -> Store]:
NullInjectorError: No provider for Store!

Fix:

import { TestBed } from '@angular/core/testing';
import { Store } from '@ngrx/store';
import { of } from 'rxjs';
import { MyComponent } from './my-component.component';

describe('MyComponent', () => {
  let mockStore: any; // Add this

  beforeEach(async () => {
    // Mock the Store
    mockStore = {
      select: jasmine.createSpy().and.returnValue(of({})),
      dispatch: jasmine.createSpy(),
    }; // Add this

    await TestBed.configureTestingModule({
      declarations: [MyComponent],
      providers: [
        { provide: Store, useValue: mockStore },
      ], // Add this
    }).compileComponents();
  });
});

Error:

PaymentsService (or its dependencies) depends on AuthService, which itself depends on Configuration. The Configuration service is not being provided in the test's TestBed.configureTestingModule, hence the error.
NullInjectorError: R3InjectorError(DynamicTestModule)[PaymentsService -> AuthService -> Configuration -> Configuration]:
NullInjectorError: No provider for Configuration!

Fix:

import { Configuration } from './config';

providers: [
  { provide: Configuration, useValue: Configuration },
]

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Common Angular Testing Errors and Fixes

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