Angular 4 Unit Testing Interview Questions

Introduction On Unit Testing Interview Questions

Unit testing is considered as a vital phase in software testing. It is not easy to write unit test cases for everyone, but it demands more practice, knowledge, and techniques. To know everything about Unit testing and tips for writing robust test cases, you should join the Unit Testing Certification program at JanBask Training. Once you are done with the training, go through this Unit Testing Interview Questions blog and evaluate your current skills level. Let us start with basic questions first then we will discuss questions for the advanced workforce too.

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Karma is a tool for executing source code against test code inside a browser environment. It supports the running of tests in each browser it’s configured for. Results are displayed on both the command line and on the browser for the developer to inspect which tests have passed or failed. Karma also watches the files and can trigger a test rerun whenever a file changes. At the root of the Angular project, we have the file karma.conf that’s used to configure Karma.

beforeAll: This function is called once, before all the specs in describe test suite are run. afterAll: This function is called once after all the specs in a test suite are finished. beforeEach: This function is called before each test specification, it function, has been run. afterEach: This function is called after each test specification has been run.

Protractor is an end-to-end test framework for Angular. It runs your tests inside a real browser, interacting with it as real person would. Unlike unit tests, where we test individual functions, here we test the entire logic. Protractor is able to fill in forms, click buttons and confirm that the expected data and styling is displayed in the HTML document. Just like Karma, Protractor has its own configuration file at the root of your Angular project, protractor.conf:

Unit testing or private testing is used to test the system’s components. This process is s best practice to test small separate pieces of code. If the unit testing depends on any of the external resources such as networks, APIs and databases, then it won’t be listed as a unit test.

Dependency injection is important in Angular because it allows for greater flexibility and modularity in the code. By injecting dependencies, we can more easily change the behavior of our code without having to make major changes to the code itself. This can be especially useful in unit testing, where we can mock dependencies to more easily test our code.

Communication in Angular can be achieved between components using a number of methods. One way is to use the @Input and @Output decorators. The @Input decorator allows data to be passed down from a parent component to a child component. The @Output decorator allows data to be passed up from a child component to a parent component. Another way to achieve communication is to use a shared service. A shared service is a service that can be injected into any number of components and provides a way for those components to share data and communicate with each other.

In Angular, a service is simply a class that can be used to provide some sort of functionality to your application. For example, you could create a service that handles all of the data storage and retrieval for your application. To code a custom service, you would simply create a new class and then register it with the Angular injector.

There are four different types of guards in Angular: CanActivate, CanDeactivate, CanLoad, and Resolve. CanActivate is used to determine if a route can be activated, while CanDeactivate is used to determine if a route can be deactivated. CanLoad is used to prevent lazy-loaded modules from being loaded until the guard conditions are met, and Resolve is used to pre-fetch data before a route is activated.

Pure pipes are used in Angular to only re-evaluate a pipe when the input to the pipe changes. This means that if the input to the pipe is an object, the pipe will only re-evaluate when the object reference changes. This can be useful for performance reasons, as re-evaluating a pipe can be expensive.

Angular Testing – Top Interview Questions and Answers | ARC Tutorials

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