Spring JPA : test interface-based projection using factory

In this short article, I'll show you how you can easily test a repository method which uses interface-based projection.

Our repository:

	@Repository
	public interface MeasuringUncertaintyRepository extends JpaRepository<MeasuringUncertainty, String> {
	<T> List<T> findByDeviceIdOrderById(String id, Class<T> clazz);
	}

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You can use the above method this ways:

	//...
	public List<MeasuringUncertaintyMedium> findUncertaintiesMediumByDevice(String deviceId) {
	Validate.notNull(deviceId, "The device identification should be provided");
	return measuringUncertaintyRepository.findByDeviceIdOrderById(deviceId, MeasuringUncertaintyMedium.class);
	}
	public List<MeasuringUncertaintyShort> findUncertaintiesShortByDevice(String deviceId) {
	Validate.notNull(deviceId, "The device identification should be provided");
	return measuringUncertaintyRepository.findByDeviceIdOrderById(deviceId, MeasuringUncertaintyShort.class);
	}
	//...

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I use the ProjectionFactory as well as the SpelAwareProxyProjectionFactory for testing (spring doc).

	//imports...
	import org.springframework.data.projection.ProjectionFactory;
	import org.springframework.data.projection.SpelAwareProxyProjectionFactory;
	@RunWith(SpringRunner.class)
	@SpringBootTest(classes = Application.class)
	@AutoConfigureMockMvc
	public class MeasuringDeviceControllerTest {
	private final ProjectionFactory factory = new SpelAwareProxyProjectionFactory();
	@Test
	public void givenMediumMode_whenGetUncertaintiesByDevice_thenReturnsStatus200() throws Exception {
	//create interface-based projection using factory
	MeasuringUncertaintyMedium uncertainty1 = factory.createProjection(MeasuringUncertaintyMedium.class);
	uncertainty1.setId("id1");
	uncertainty1.setMode(Mode.TENSION_ALT_400HZ);
	uncertainty1.setUncertaintyUnit(UncertaintyUnit.PERCENT);
	uncertainty1.setUncertaintyValue(new BigDecimal("0.01"));
	uncertainty1.setUnit(MeasuringUnit.MV);
	//...
	}
	}

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You must also provide the setters on your interface as follow:

	public interface MeasuringUncertaintyMedium {
	String getId();
	void setId(String id);
	Mode getMode();
	void setMode(Mode mode);
	MeasuringUnit getUnit();
	void setUnit(MeasuringUnit unit);
	BigDecimal getUncertaintyValue();
	void setUncertaintyValue(BigDecimal value);
	UncertaintyUnit getUncertaintyUnit();
	void setUncertaintyUnit(UncertaintyUnit unit);
	}

view raw jpa_repository_withprojection_interface hosted with ❤ by GitHub

Happy reading...