Basic Example of Spring Junit Testing
Note - this is basic Spring - not Spring Boot - sourced from https://mkyong.com/unittest/junit-spring-integration-example/
Branches
This is the master branch. Have a look at the other branches for more variations:
- master - 1 impl service of DataModelService, field autowiring
- two-services - 2 classes that implement DataModelService, field autowiring
- beanmaker - 1 impl service of DataModelService, field autowiring, @Bean
What the App Does
Well, there isn't really an app - nothing to run as such.
All we have is:
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AppConfig.java - configuration file that tells Spring to scan package com.gillianbc.spring
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DataModelService.java - interface with an isValid() method
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MachineLearningService - impl class of the DataModelService. Annotated with @Service and named "mach" so Spring will manage it in the application context and call it "mach"
What the test class does
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@RunWith(SpringJUnit4ClassRunner.class) - Indicates that the class should use Spring's JUnit facilities.
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@ContextConfiguration(classes = {AppConfig.class}) - tells the test class what classes to use to configure spring. Note we could have multiple in here if necessary
The above annotations means the spring context is loaded for us. To test the MachineLearningService, we need a spring managed instance of that class. If we just initialised it, it wouldn't be a spring bean - spring has a MachineLearningService and we'd just be creating another instance of that class. If it had any dependencies on spring properties or other beans, it wouldn't know about them. So to test it we ask spring to assign it for us - by autowiring.
@Autowired @Qualifier("mach")
i.e. tells spring have a look in the application context and use the bean called "mach" that implements the DataModelService