Added test case coverage to newly created controller

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

@@ -0,0 +1,99 @@
+package org.springframework.samples.petclinic.owner;
+
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.mockito.Mockito;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest;
+import org.springframework.boot.test.mock.mockito.MockBean;
+import org.springframework.hateoas.EntityModel;
+import org.springframework.http.MediaType;
+import org.springframework.test.web.servlet.MockMvc;
+
+import static org.hamcrest.Matchers.is;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.when;
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.*;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.*;
+
+@WebMvcTest(NewPetController.class)
+class NewPetControllerTest {
+
+	@Autowired
+	private MockMvc mockMvc;
+
+	@MockBean
+	private NewPetRepository petRepository;
+
+	private NewPet testPet;
+
+	private PetType testPetType;
+
+	@BeforeEach
+	void setup() {
+
+		testPetType = new PetType();
+		testPetType.setId(1);
+		testPetType.setName("Test");
+
+		testPet = new NewPet();
+		testPet.setId(1);
+		testPet.setName("Buddy");
+		testPet.setType(testPetType);
+	}
+
+	@Test
+	void getPetById_found() throws Exception {
+		when(petRepository.findById(1)).thenReturn(testPet);
+
+		mockMvc.perform(get("/owners/1/pet/1"))
+			.andExpect(status().isOk())
+			.andExpect(jsonPath("$.id", is(1)))
+			.andExpect(jsonPath("$.name", is("Buddy")))
+			.andExpect(jsonPath("$.type.name", is("Test")))
+			.andExpect(jsonPath("$._links.self.href").exists())
+			.andExpect(jsonPath("$._links.create-new-pet.href").exists());
+	}
+
+	@Test
+	void getPetById_notFound() throws Exception {
+		when(petRepository.findById(99)).thenReturn(null);
+
+		mockMvc.perform(get("/owners/1/pet/99")).andExpect(status().isNotFound());
+	}
+
+	@Test
+	void createNewPet_success() throws Exception {
+
+		testPetType = new PetType();
+		testPetType.setId(1);
+		testPetType.setName("Test1");
+
+		NewPet newPet = new NewPet();
+		newPet.setId(2);
+		newPet.setName("Whiskers");
+		newPet.setType(testPetType);
+
+		when(petRepository.save(any(NewPet.class))).thenReturn(newPet);
+
+		mockMvc.perform(post("/owners/1/pet").contentType(MediaType.APPLICATION_JSON).content(asJsonString(newPet)))
+			.andExpect(status().isCreated())
+			.andExpect(jsonPath("$.id", is(2)))
+			.andExpect(jsonPath("$.name", is("Whiskers")))
+			.andExpect(jsonPath("$.type.name", is("Test1")))
+			.andExpect(jsonPath("$._links.self.href").exists());
+	}
+
+	// Utility method to convert objects to JSON string
+	private static String asJsonString(Object obj) {
+		try {
+			return new ObjectMapper().writeValueAsString(obj);
+		}
+		catch (Exception e) {
+			throw new RuntimeException("Failed to convert object to JSON string", e);
+		}
+	}
+
+}