Can you answer the interview question about unit testing in Angular?

This article will introduce to you some interview questions about unit testing in Angular. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to everyone.

What are the types of tests in Angular and which testing frameworks are they based on?

Angular’s ​​tests mainly include unit tests (Unit Test) and end-to-end tests ( e2e).

• Unit Test: Based on jasmine and Karma. Jasmine is a universal testing framework that is widely used in addition to Angular. Karma is a framework specific to Angular for managing test configurations, etc., allowing test code to be easily executed in designated browsers. In addition, depending on preference, you can also Choose Mocha and Chai.
• End-to-end testing (e2e): based on protractor. protractor is an e2e framework dedicated to Angular. [Related tutorial recommendations: "angular tutorial"]

What is Karma? What does it do in Angular?

Karma is a tool for executing source code against test code in a browser environment. It supports running tests in every browser configured for it. Display the results simultaneously on the command line and browser, or enter a standard format report for developers to check which tests passed or failed. Karma also monitors files and can trigger test reruns whenever a file changes. At the same time, Karma can also count code coverage (Code Coverage).
In the root directory of the Angular project, we have the file karma.conf for configuring Karma.

What is Jasmine? What is the use in Angular?

Jasmine is a javascript testing framework that supports a software development practice called behavior-driven development, or BDD for short. This is a special style of test-driven development (TDD).

Jasmine and BDD generally try to describe tests in a human-readable format so that non-technical people can understand what is being tested.

What is a protractor?

protractor is Angular’s ​​end-to-end testing framework. It runs tests in a real browser and interacts with it like a real person. Unlike unit testing, where we test individual features, here we test the entire logic. Protractor is able to fill out forms, click buttons, and confirm that the expected data and styles appear in the HTML document.

Just like Karma, Protractor has its own configuration file in protractor.conf in the root directory of the Angular project.

Unit Test Unit Test

#What is unit testing in Angular?

Unit testing is used to test a single function in isolation, a single component, and is characterized by isolation and star speed. In this unit test, we cannot say that everything in the application is fine, but only for a single unit or function, it is guaranteed to work properly.

Best practices for Angular UT

• Initialize the context used in beforeEach();
• The description in describe(), it() should be clear. Easy to read and easy to locate quickly when the test fails;
• Use after(), afterEach() to reset the global state changed by the test;
• For each specific test case, don’t be too complicated, try to Guaranteed to be within 15 lines of code

What is TestBed and what does it do

TestBed is the Angular testing tool set (@angular/ core/testing) is used to build a @NgModule test environment module. You can

• TestBed.configureTestingModule to prepare the test environment

• Use TestBed.createComponent to create a test component for testing the target component

#How to deal with other dependencies when testing Service?

To create a use case using TestBed, add dependencies to providers

TestBed.configureTestingModule({
  providers: [YourDependencyService]
});

End-to-end testing (e2e)

Based on Protractor, the testing cost is relatively high, and it can generally cover the sunny case.

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