Optimization of unit test efficiency: why test programs? What are the benefits of testing?

unit testing （Unit Testing） Also known as module testing , It's for program modules （ The smallest unit of software design ） To test the correctness . A program unit is the smallest testable part of an application . Simply speaking , It is to test whether the stability of the data meets the expectations of the program . When it comes to testing , Why should we test the program ？ What benefits does testing bring to the program ？

We may inadvertently make mistakes in our daily development , If you wait until the final stage to test the project results , Found a mistake , It's hard for us to find it at this time Bug Where is the source of . We all know , It is possible that an error will lead to a step-by-step error .

The test is in our above statement , It's very important , When we finish a small module of the project , First, test whether the small module is correct or meets the expectations , If it is wrong or does not meet expectations, it needs to be revised repeatedly , Until correct or expected , That is, unit tests are used .

The coding specification of unit test generally involves the following contents ：

Class name ： Define test classes , The class name is determined by the name of the tested class Test constitute . for example ：CalculatorTest;

Package name ： The defined test class needs to be placed in xxx.xxx.xxx.test In bag . for example ：package com.autodrive.test;

Method name ： The method name of a test method can be defined in two ways test Test methods and test methods . for example ：testCheck and check;

Return value ： Because our method is only tested in class , Can run independently , So you don't need to process any return values , So here we use void. for example ：public void check();

parameter list ： Because our method is used to test , As for the input of parameter list, it is not necessary . When testing, we can pass in the required parameters by ourselves . So this parameter list is empty . for example ： for example ：public void check();

@Test annotation ： Tests need to be run to complete . If we only have one main Method , Obviously, we still need to comment out the tested structures . To solve this problem, we need to add... Above the test method @Test Annotation to complete the test , As long as it is the method of adding the annotation , You can run this method alone to complete the test .

IDEA Quick import Junit4、5： Use IDEA Little buddy , Here comes your gospel . We can create test classes and methods first , Then add... Above the test method @Test annotation , here IDEA According to the @Test The annotation is red , That's when we use Alt + Enter Key combination to open the import Junit Unit test list , Then choose Junit4 perhaps Junit5 determine .

stay SpringBoot The following notes and descriptions are often used in unit tests ：

@RunWith(SpringRunner.class)

@SpringBootTest(classes = Application.class)

@Transactional

@Rollback(true) // Automatic transaction rollback , The default is true. Don't write

public class NoticeServiceTest {

@Autowired

private NoticeService noticeService;

@Test

public void sayHello() {

helloService.sayHello("zhangsan");

}

}

In the example above ,@SpringBootTest Launched the SpringBoot Environmental Science , Scan the application for spring To configure , And build a complete Spring Context, Its classes = Application.class Started the whole project . adopt @SpringBootTest We can specify the startup class , Or to @SpringBootTest Parameters of webEnvironment The assignment is SpringBootTest.WebEnvironment.RANDOM_PORT, This will start web Containers , And listen to a random port , meanwhile , Automatically assemble one for us TestRestTemplate Type of bean To assist us in sending test requests .

@Transactional Indicates that the database is called and transacted ;@RunWith(SpringRunner.class) The statement in Spring Unit testing in the environment of , such Spring The relevant annotations will be recognized and take effect , and @Autowired Launched the Spring.

When the project uses @Component annotation , stay SpringBoot When the project starts, it will be instantiated / start-up , This @Component Annotated classes have multithreaded methods , As defined in the startup class ApplicationStartup Class started , So when you execute unit tests , Due to the impact of multithreaded tasks , It may cause data modification to your database , Even if you use the transaction rollback annotation .

Efficient unit tests should be separated from the database , To meet the requirements of quick start and complete the test 、 Support the requirements of inter service invocation . The above example can be optimized through the following points ：

1. start-up Spring Will make run->Junit Test The program slows down , This is one of the reasons why running unit tests is slow every time . Then unit testing is to test only the methods of a certain class , start-up Spring Many times it is superfluous , So we only need the corresponding entity class instance . Inject... When needed bean When , We directly new.

private NoticeService noticeService = new NoticeService();

2. @SpringBootTest Is in SpringBoot Used on the project , It's in @SpringBootContextLoader On the basis of , Reading of configuration file attributes , Will read 、 Parse some project configuration files , Also connect to the database , Then if the startup class has another startup class 、@Component、 Multithreading etc. , Unit tests can often avoid starting SpringBoot, Reduce the amount of time it takes to start , I don't use @SpringBootTest annotation .

3. Assertions should be used to determine whether unit test results meet expectations .

4. @RunWith stay JUnit Many of them Runner, They are responsible for invoking specific test code , every last Runner Each has its own special functions , You have to choose different... According to your needs Runner To run your test code , And they usually use SpringRunner.class. If we simply do ordinary Java test , Don't involve Spring Web project , It can be omitted @RunWith annotation , In this way, the system will automatically use the default Runner To run your code .

5. Unit tests can pass Mock The data method avoids the call to the database , Reduce a lot of database connection time .Mock It is a step to simulate all operations on the database , Do not execute any SQL, If we directly simulate the code execution of this operation database, it will be successful , And it can simulate any return value , There are two main comments . As long as it's local , His writing bean, You can use @MockBean, It will simulate all the methods of operating the database . If it is a method without a return value , We can leave it alone . If it is a method with a return value , We can give it back the values we need to simulate . If it is our local , Call another company , Interfaces written for us elsewhere , Not to operate our own database , It is we who have written the reference , Others give us a return value , We will use @SpyBean.

Mock The necessary dependencies are as follows ：

<dependency>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-test</artifactId>

<scope>test</scope>

</dependency>

Through the above optimization , It can greatly shorten our single test time , Improve our development efficiency .

Last ：

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