Angular Typescript Jest unit test is not failing for console errors or unknown elements

When writing unit tests for Angular applications using TypeScript and Jest, it is important to ensure that all errors and unknown elements are properly caught and reported. However, sometimes the unit tests may not fail even if there are console errors or unknown elements present. In this blog post, we will explore the possible solutions to this problem.

Solution 1: Configuring Jest to fail on console errors

Jest provides an option to fail the test if there are any console errors. To enable this option, you need to modify the Jest configuration in your jest.config.js file. Add the following code snippet to the configuration:

{
  // ... other Jest configuration options
  setupFilesAfterEnv: ['/src/setupJest.ts'],
  testMatch: ['**/*.spec.ts'],
  globals: {
    'ts-jest': {
      diagnostics: {
        ignoreCodes: [151001]
      }
    }
  }
}

The setupFilesAfterEnv option allows you to specify a setup file that will be executed before each test. In the setup file, you can configure Jest to fail on console errors by adding the following code:

// src/setupJest.ts
beforeEach(() => {
  jest.spyOn(console, 'error').mockImplementation((...args) => {
    throw new Error(...args);
  });
});

With this configuration, any console error encountered during the unit test will result in a failed test.

Solution 2: Using Angular TestBed to catch unknown elements

In some cases, the unit tests may not fail even if there are unknown elements present in the Angular template. To catch these unknown elements, you can use the Angular TestBed. The TestBed allows you to compile the Angular component and detect any errors or unknown elements. Here’s an example:

import { TestBed } from '@angular/core/testing';
import { MyComponent } from './my.component';

describe('MyComponent', () => {
  beforeEach(async () => {
    await TestBed.configureTestingModule({
      declarations: [MyComponent]
    }).compileComponents();
  });

  it('should create the component', () => {
    const fixture = TestBed.createComponent(MyComponent);
    const component = fixture.componentInstance;
    expect(component).toBeTruthy();
  });
});

In this example, we use the TestBed’s configureTestingModule method to configure the testing module and include the component we want to test. Then, we create the component using TestBed.createComponent and assert that the component exists using expect(component).toBeTruthy(). If there are any unknown elements or errors in the template, the test will fail.

By using the above solutions, you can ensure that your unit tests fail when there are console errors or unknown elements present. This will help you catch any potential issues and ensure the reliability of your Angular application.

That’s it for this blog post! We hope you found these solutions helpful in resolving the issue of Jest unit tests not failing for console errors or unknown elements in Angular TypeScript applications. Happy testing!

Angular Typescript Jest unit test is not failing for console errors or unknown elements