Populating Spring Value during Unit Test

Question

I m trying to write a Unit Test for a simple bean that s used in my program to validate forms  The bean is annotated with  Component and has a class variable that is initialized using    Value    this property value    private String thisProperty    I would like to write unit tests for the validation methods inside this class  however  if possible I would like to do so without utilizing the properties file  My reasoning behind this  is that if the value I m pulling from the properties file changes  I would like that to not affect my test case  My test case is testing the code that validates the value  not the value itself    Is there a way to use Java code inside my test class to initialize a Java class and populate the Spring  Value property inside that class then use that to test with   I did find this How To that seems to be close  but still uses a properties file  I would rather it all be Java code

User · Accepted Answer

If possible I would try to write those test without Spring Context. If you create this class in your test without spring, then you have full control over its fields.

To set the @value field you can use Springs ReflectionTestUtils - it has a method setField to set private fields.

@see JavaDoc: ReflectionTestUtils.setField(java.lang.Object, java.lang.String, java.lang.Object)

User · Answer

Its quite old question  and I m not sure if it was an option at that time  but this is the reason why I always prefer DependencyInjection by the constructor than by the value  I can imagine that your class might look like this  class ExampleClass       Autowired    private Dog dog       Value  quot   this property value  quot       private String thisProperty         other stuff       You can change it to  class ExampleClass      private Dog dog     private String thisProperty        optionally  Autowire    public ExampleClass final Dog dog   Value  quot   this property value  quot   final String thisProperty         this dog   dog        this thisProperty   thisProperty              other stuff       With this implementation  the spring will know what to inject automatically  but for unit testing  you can do whatever you need  For example Autowire every dependency wth spring  and inject them manually via constructor to create  quot ExampleClass quot  instance  or use only spring with test property file  or do not use spring at all and create all object yourself

User · Answer

Since Spring 4 1 you could set up property values just in code by using org springframework test context TestPropertySource annotation on Unit Tests class level  You could use this approach even for injecting properties into dependent bean instances  For example   RunWith SpringJUnit4ClassRunner class   ContextConfiguration classes   FooTest Config class   TestPropertySource properties          some bar value testValue      public class FooTest       Value    some bar value      String bar      Test   public void testValueSetup         assertEquals  testValue   bar            Configuration   static class Config         Bean     public static PropertySourcesPlaceholderConfigurer propertiesResolver             return new PropertySourcesPlaceholderConfigurer                    Note  It s necessary to have instance of org springframework context support PropertySourcesPlaceholderConfigurer in Spring context  Edit 24-08-2017  If you are using SpringBoot 1 4 0 and later you could initialize tests with  SpringBootTest and  SpringBootConfiguration annotations  More info here  In case of SpringBoot we have following code   SpringBootTest  SpringBootConfiguration  RunWith SpringJUnit4ClassRunner class   TestPropertySource properties          some bar value testValue      public class FooTest       Value    some bar value      String bar      Test   public void testValueSetup         assertEquals  testValue   bar

User · Answer

Spring Boot do a lot of automatically things to us but when we use the annotation  SpringBootTest we think that everything will be automatically solved by Spring boot  There are a lot of documentation  but the minimal is to choose one engine   RunWith SpringRunner class   and indicate the class that will be used create the context to load the configuration  resources applicationl properties   In a simple way you need the engine and the context   RunWith SpringRunner class   SpringBootTest classes   MyClassTest  class  public class MyClassTest         Value  quot   my property  quot       private String myProperty        Test     public void checkMyProperty            Assert assertNotNull my property            Of course  if you look the Spring Boot documentation you will find thousands os ways to do that

User · Answer

This seems to work  although still a bit verbose  I d like something shorter still     BeforeClass public static void beforeClass         System setProperty  some property     lt value gt           Optionally   AfterClass public static void afterClass         System clearProperty  some property

User · Answer

Adding PropertyPlaceholderConfigurer in configuration is working for me    Configuration  ComponentScan  EnableJpaRepositories  EnableTransactionManagement public class TestConfiguration        Bean     public DataSource dataSource             EmbeddedDatabaseBuilder builder   new EmbeddedDatabaseBuilder            builder setType EmbeddedDatabaseType DERBY           return builder build                Bean     public LocalContainerEntityManagerFactoryBean entityManagerFactory             LocalContainerEntityManagerFactoryBean entityManagerFactoryBean   new LocalContainerEntityManagerFactoryBean            entityManagerFactoryBean setDataSource dataSource             entityManagerFactoryBean setPackagesToScan new String      com test model                 Use hibernate         JpaVendorAdapter vendorAdapter   new HibernateJpaVendorAdapter            entityManagerFactoryBean setJpaVendorAdapter vendorAdapter           entityManagerFactoryBean setJpaProperties getHibernateProperties             return entityManagerFactoryBean             private Properties getHibernateProperties             Properties properties   new Properties            properties put  hibernate show sql    false            properties put  hibernate dialect    org hibernate dialect DerbyDialect            properties put  hibernate hbm2ddl auto    update            return properties              Bean     public JpaTransactionManager transactionManager             JpaTransactionManager transactionManager   new JpaTransactionManager             transactionManager setEntityManagerFactory                entityManagerFactory   getObject                         return transactionManager              Bean     PropertyPlaceholderConfigurer propConfig             PropertyPlaceholderConfigurer placeholderConfigurer   new PropertyPlaceholderConfigurer            placeholderConfigurer setLocation new ClassPathResource  application test properties             return placeholderConfigurer            And in test class   RunWith SpringJUnit4ClassRunner class   SpringApplicationConfiguration classes   TestConfiguration class  public class DataServiceTest         Autowired     private DataService dataService        Autowired     private DataRepository dataRepository        Value    Api url        private String baseUrl        Test     public void testUpdateData             List lt Data gt  datas    List lt Data gt   dataRepository findAll            assertTrue datas isEmpty             dataService updateDatas            datas    List lt Data gt   dataRepository findAll            assertFalse datas isEmpty

User · Answer

ExtendWith SpringExtension class         RunWith SpringJUnit4ClassRunner class   ContextConfiguration initializers   ConfigDataApplicationContextInitializer class   May that could help  The key is ConfigDataApplicationContextInitializer get all props datas

User · Answer

If you want  you can still run your tests within Spring Context and set the required properties inside Spring configuration class  If you use JUnit  use SpringJUnit4ClassRunner and define dedicated configuration class for your tests like that   The class under test    Component public SomeClass         Autowired     private SomeDependency someDependency        Value    someProperty        private String someProperty      The test class    RunWith SpringJUnit4ClassRunner class    ContextConfiguration classes   SomeClassTestsConfig class  public class SomeClassTests         Autowired     private SomeClass someClass        Autowired     private SomeDependency someDependency        Before     public void setup            Mockito reset someDependency         Test     public void someTest               And the configuration class for this test    Configuration public class SomeClassTestsConfig         Bean     public static PropertySourcesPlaceholderConfigurer properties   throws Exception           final PropertySourcesPlaceholderConfigurer pspc   new PropertySourcesPlaceholderConfigurer            Properties properties   new Properties             properties setProperty  someProperty    testValue             pspc setProperties properties           return pspc             Bean     public SomeClass getSomeClass             return new SomeClass                Bean     public SomeDependency getSomeDependency                Mockito used here for mocking dependency         return Mockito mock SomeDependency class             Having that said  I wouldn t recommend this approach  I just added it here for reference  In my opinion much better way is to use Mockito runner  In that case you don t run tests inside Spring at all  which is much more clear and simpler

User · Answer

Don t abuse private fields get set by reflection Using reflection as that is done in several answers here is something that we could avoid  It brings a small value here while it presents multiple drawbacks    we detect reflection issues only at runtime  ex  fields not existing any longer  We want  encapsulation but not a opaque class that hides dependencies that should be visible and make the class more opaque and less testable  it encourages bad design   Today you declare a  Value String field  Tomorrow you can declare 5 or 10 of them in that class and you may not even be straight aware that you decrease the design of the class  With a more visible approach to set these fields  such as constructor    you will think twice before adding all these fields and you will probably encapsulate them into another class and use  ConfigurationProperties   Make your class testable both unitary and in integration To be able to write both plain unit tests  that is without a running spring container  and integration tests for your Spring component class  you have to make this class usable with or without Spring  Running a container in an unit test when it is not required is a bad practice that slows down local builds   you don t want that  I added this answer because no answer here seems to show this distinction and so they rely on a running container systematically  So I think that you should move this property defined as an internal of the class    Component public class Foo          Value  quot   property value  quot   private String property               into a constructor parameter that will be injected by Spring    Component public class Foo         private String property            public Foo  Value  quot   property value  quot   String property          this property   property                               Unit test example You can instantiate Foo without Spring and inject any value for property thanks to the constructor    public class FooTest      Foo foo   new Foo  quot dummyValue quot         Test    public void doThat                      Integration test example You can injecting the property in the context with  Spring Boot in this simple way thanks to the properties attribute of  SpringBootTest      SpringBootTest properties  quot property value dummyValue quot   public class FooTest           Autowired    Foo foo            Test    public void doThat                           You could use as alternative   TestPropertySource but it adds an additional annotation    SpringBootTest  TestPropertySource properties  quot property value dummyValue quot   public class FooTest        With Spring  without Spring Boot   it should be a little more complicated but as I didn t use Spring without Spring Boot from a long time I don t prefer say a stupid thing  As a side note   if you have many  Value fields to set  extracting them into a class annotated with  ConfigurationProperties is more relevant because we don t want a constructor with too many arguments

User · Answer

In springboot 2 4 1 im just added annotation  SpringBootTest in my test  and obviously  setted spring profiles active   test in my src test resources application yml Im using  ExtendWith  SpringExtension class   and  ContextConfiguration classes    RabbitMQ class  GenericMapToObject class  ModelMapper class  StringUtils class   for external confs

[java] Populating Spring @Value during Unit Test

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