Building Java Applications with Gradle

Gradle wrapper:

• In order to make sure you build the project with the same version of gradle as other developers (which can make a big difference), build the application using the wrapper: ./gradlew
  It will start with downloading the right gradle version, unless it's already there.
• Watch out for running old gradlew for a version like 2.3 with a new java like version 11.  It quits silently without doing anything.

Useful commands:

• gradle build -x test  -- run build but skip tests

Querying for Data in a Java Spring App - Alternatives

1. Create a method with a name including all attributes you want to query by in your PersonRepository interface that implements CrudRepository<> (or PagingAndSortingRepository<>)
2. Create a Specification object and use Spring findAll to find all records matching the Specification.
3. Use @Query in the PersonRepository and define the query using JQL
4. Use GraphQL (see for example https://docs.spring.io/spring-data/jpa/docs/current/reference/html/#core.extensions.querydsl)

Unit testing with jUnit5 and Mockito

Mocking for Spring injected dependencies

import org.junit.jupiter.api.Test;

@ExtendWith(MockitoExtension.class)

class Person {

   @Mock

   DependencyA dependencyA;

   // Don't use @InjectMocks if using constructor injection with final dependencies.
   // Mockito can't set the new mocks for each test

   TestedClass target;

   @BeforeEach

   public void setup() {

      // only needed if you do Mockito.when(dependencyA.methodAbc()).thenReturn() or similar

      MockitoAnnotations.initialize(this);  
      target = new TestedClass(dependencyA);

   }

   @Test

   public void testMethodWhatsyourname() {

      // given

      ...

      

      // when

      target.whatsYourName();

      // then 

      ...

   }

}