refactor OwnerRepository:

-<replace>: use `JpaRepository` to replace `Repository` in `OwnerRepository` class.
-<remove1>: remove `save()` method. JpaRepository provides it by default.
-<remove2>: remove `@Query` because in `Owner` class, the `@OneToMany` annotiation achieved `fetch` in query.
-<refactor1>: use `Optional<Owner>` to recieve the result from `findById()`, and if is null, throw `IllegalArugmentExpection`.
-<refactor2>: achieve the assert to judge return value in tests.
-<add>: add name to `@author` tag.

src/test/java/org/springframework/samples/petclinic/owner/OwnerControllerTests.java

@@ -31,6 +31,7 @@ import org.springframework.test.web.servlet.MockMvc;
 import org.springframework.test.web.servlet.request.MockMvcRequestBuilders;
 
 import java.time.LocalDate;
+import java.util.Optional;
 
 import static org.hamcrest.Matchers.empty;
 import static org.hamcrest.Matchers.greaterThan;
@@ -52,6 +53,7 @@ import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.
  * Test class for {@link OwnerController}
  *
  * @author Colin But
+ * @author Wick Dynex
  */
 @WebMvcTest(OwnerController.class)
 @DisabledInNativeImage
@@ -94,7 +96,7 @@ class OwnerControllerTests {
 
 		given(this.owners.findAll(any(Pageable.class))).willReturn(new PageImpl<>(Lists.newArrayList(george)));
 
-		given(this.owners.findById(TEST_OWNER_ID)).willReturn(george);
+		given(this.owners.findById(TEST_OWNER_ID)).willReturn(Optional.of(george));
 		Visit visit = new Visit();
 		visit.setDate(LocalDate.now());
 		george.getPet("Max").getVisits().add(visit);
@@ -240,7 +242,7 @@ class OwnerControllerTests {
 		owner.setCity("New York");
 		owner.setTelephone("0123456789");
 
-		when(owners.findById(pathOwnerId)).thenReturn(owner);
+		when(owners.findById(pathOwnerId)).thenReturn(Optional.of(owner));
 
 		mockMvc.perform(MockMvcRequestBuilders.post("/owners/{ownerId}/edit", pathOwnerId).flashAttr("owner", owner))
 			.andExpect(status().is3xxRedirection())

src/test/java/org/springframework/samples/petclinic/owner/PetControllerTests.java

@@ -46,6 +46,7 @@ import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.
  * Test class for the {@link PetController}
  *
  * @author Colin But
+ * @author Wick Dynex
  */
 @WebMvcTest(value = PetController.class,
 		includeFilters = @ComponentScan.Filter(value = PetTypeFormatter.class, type = FilterType.ASSIGNABLE_TYPE))
@@ -79,7 +80,7 @@ class PetControllerTests {
 		dog.setId(TEST_PET_ID + 1);
 		pet.setName("petty");
 		dog.setName("doggy");
-		given(this.owners.findById(TEST_OWNER_ID)).willReturn(owner);
+		given(this.owners.findById(TEST_OWNER_ID)).willReturn(Optional.of(owner));
 	}
 
 	@Test

src/test/java/org/springframework/samples/petclinic/owner/VisitControllerTests.java

@@ -32,10 +32,13 @@ import org.springframework.boot.test.mock.mockito.MockBean;
 import org.springframework.test.context.aot.DisabledInAotMode;
 import org.springframework.test.web.servlet.MockMvc;
 
+import java.util.Optional;
+
 /**
  * Test class for {@link VisitController}
  *
  * @author Colin But
+ * @author Wick Dynex
  */
 @WebMvcTest(VisitController.class)
 @DisabledInNativeImage
@@ -58,7 +61,7 @@ class VisitControllerTests {
 		Pet pet = new Pet();
 		owner.addPet(pet);
 		pet.setId(TEST_PET_ID);
-		given(this.owners.findById(TEST_OWNER_ID)).willReturn(owner);
+		given(this.owners.findById(TEST_OWNER_ID)).willReturn(Optional.of(owner));
 	}
 
 	@Test

src/test/java/org/springframework/samples/petclinic/service/ClinicServiceTests.java

@@ -20,6 +20,7 @@ import static org.assertj.core.api.Assertions.assertThat;
 
 import java.time.LocalDate;
 import java.util.Collection;
+import java.util.Optional;
 
 import org.junit.jupiter.api.Test;
 import org.springframework.beans.factory.annotation.Autowired;
@@ -90,7 +91,9 @@ class ClinicServiceTests {
 
 	@Test
 	void shouldFindSingleOwnerWithPet() {
-		Owner owner = this.owners.findById(1);
+		Optional<Owner> optionalOwner = this.owners.findById(1);
+		assertThat(optionalOwner).isPresent();
+		Owner owner = optionalOwner.get();
 		assertThat(owner.getLastName()).startsWith("Franklin");
 		assertThat(owner.getPets()).hasSize(1);
 		assertThat(owner.getPets().get(0).getType()).isNotNull();
@@ -119,7 +122,9 @@ class ClinicServiceTests {
 	@Test
 	@Transactional
 	void shouldUpdateOwner() {
-		Owner owner = this.owners.findById(1);
+		Optional<Owner> optionalOwner = this.owners.findById(1);
+		assertThat(optionalOwner).isPresent();
+		Owner owner = optionalOwner.get();
 		String oldLastName = owner.getLastName();
 		String newLastName = oldLastName + "X";
 
@@ -127,7 +132,9 @@ class ClinicServiceTests {
 		this.owners.save(owner);
 
 		// retrieving new name from database
-		owner = this.owners.findById(1);
+		optionalOwner = this.owners.findById(1);
+		assertThat(optionalOwner).isPresent();
+		owner = optionalOwner.get();
 		assertThat(owner.getLastName()).isEqualTo(newLastName);
 	}
 
@@ -144,7 +151,10 @@ class ClinicServiceTests {
 	@Test
 	@Transactional
 	void shouldInsertPetIntoDatabaseAndGenerateId() {
-		Owner owner6 = this.owners.findById(6);
+		Optional<Owner> optionalOwner = this.owners.findById(6);
+		assertThat(optionalOwner).isPresent();
+		Owner owner6 = optionalOwner.get();
+
 		int found = owner6.getPets().size();
 
 		Pet pet = new Pet();
@@ -157,7 +167,9 @@ class ClinicServiceTests {
 
 		this.owners.save(owner6);
 
-		owner6 = this.owners.findById(6);
+		optionalOwner = this.owners.findById(6);
+		assertThat(optionalOwner).isPresent();
+		owner6 = optionalOwner.get();
 		assertThat(owner6.getPets()).hasSize(found + 1);
 		// checks that id has been generated
 		pet = owner6.getPet("bowser");
@@ -167,7 +179,10 @@ class ClinicServiceTests {
 	@Test
 	@Transactional
 	void shouldUpdatePetName() {
-		Owner owner6 = this.owners.findById(6);
+		Optional<Owner> optionalOwner = this.owners.findById(6);
+		assertThat(optionalOwner).isPresent();
+		Owner owner6 = optionalOwner.get();
+
 		Pet pet7 = owner6.getPet(7);
 		String oldName = pet7.getName();
 
@@ -175,7 +190,9 @@ class ClinicServiceTests {
 		pet7.setName(newName);
 		this.owners.save(owner6);
 
-		owner6 = this.owners.findById(6);
+		optionalOwner = this.owners.findById(6);
+		assertThat(optionalOwner).isPresent();
+		owner6 = optionalOwner.get();
 		pet7 = owner6.getPet(7);
 		assertThat(pet7.getName()).isEqualTo(newName);
 	}
@@ -194,7 +211,10 @@ class ClinicServiceTests {
 	@Test
 	@Transactional
 	void shouldAddNewVisitForPet() {
-		Owner owner6 = this.owners.findById(6);
+		Optional<Owner> optionalOwner = this.owners.findById(6);
+		assertThat(optionalOwner).isPresent();
+		Owner owner6 = optionalOwner.get();
+
 		Pet pet7 = owner6.getPet(7);
 		int found = pet7.getVisits().size();
 		Visit visit = new Visit();
@@ -210,7 +230,10 @@ class ClinicServiceTests {
 
 	@Test
 	void shouldFindVisitsByPetId() {
-		Owner owner6 = this.owners.findById(6);
+		Optional<Owner> optionalOwner = this.owners.findById(6);
+		assertThat(optionalOwner).isPresent();
+		Owner owner6 = optionalOwner.get();
+
 		Pet pet7 = owner6.getPet(7);
 		Collection<Visit> visits = pet7.getVisits();