Added more tests to increase the test coverage

backend/src/main/java/com/example/backend/controller/ShoppingListController.java

@@ -8,7 +8,6 @@
 import org.springframework.web.bind.annotation.*;
 
 import java.util.List;
-import java.util.NoSuchElementException;
 
 @RestController
 @AllArgsConstructor
@@ -22,12 +21,8 @@ public List<ShoppingList> getAllLists(){
     }
 
     @GetMapping("/{id}")
-    public ShoppingList getListById(@PathVariable String id){
-        ShoppingList shoppingList = shoppingListService.getListById(id);
-        if (shoppingList == null) {
-            throw new NoSuchElementException("List not found");
-        }
-        return shoppingList;
+    public ShoppingList getListById(@PathVariable String id) {
+        return shoppingListService.getListById(id);
     }
 
     @PostMapping

backend/src/main/java/com/example/backend/service/ShoppingListService.java

@@ -21,7 +21,8 @@ public List<ShoppingList> getAllLists() {
     }
 
     public ShoppingList getListById(String id) {
-        return shoppingListRepository.findById(id).orElse(null);
+
+        return shoppingListRepository.findById(id).orElseThrow(() -> new NoSuchElementException("List not found"));
     }
 
     public ShoppingList createShoppingList(ShoppingList shoppingList) {

backend/src/test/java/com/example/backend/controller/ShoppingListControllerTest.java

@@ -15,9 +15,7 @@
 import org.springframework.test.web.servlet.MockMvc;
 import org.springframework.test.web.servlet.request.MockMvcRequestBuilders;
 
-import java.util.Arrays;
 import java.util.List;
-import java.util.NoSuchElementException;
 import java.util.Optional;
 
 import static org.mockito.Mockito.verify;
@@ -46,7 +44,7 @@ void getAllLists_shouldReturnAllLists() throws Exception {
         Product product2 = new Product("cheese", 10);
         List<Product> products = List.of(product1, product2);
         ShoppingList shoppingList = new ShoppingList("1", "new 1", "make smth", products);
-        when(shoppingListRepository.findAll()).thenReturn(Arrays.asList(shoppingList));
+        when(shoppingListRepository.findAll()).thenReturn(List.of(shoppingList));
 
         mockMvc.perform(MockMvcRequestBuilders.get("/api/lists"))
                 .andExpect(status().isOk())
@@ -90,7 +88,8 @@ void getListById_shouldReturnListById() throws Exception {
     @Test
     @DirtiesContext
     void getListById_shouldReturnNotFoundIfListDoesNotExist() throws Exception {
-        when(shoppingListService.getListById("2")).thenThrow(new NoSuchElementException("List not found"));
+        when(shoppingListRepository.findById("2")).thenReturn(Optional.empty());
+
         mockMvc.perform(MockMvcRequestBuilders.get("/api/lists/2"))
                 .andExpect(status().isNotFound())
                 .andExpect(jsonPath("$.message").value("List not found"));

backend/src/test/java/com/example/backend/exception/GlobalExceptionHandlerTest.java

@@ -0,0 +1,35 @@
+package com.example.backend.exception;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest;
+import org.springframework.test.web.servlet.MockMvc;
+import org.springframework.test.web.servlet.setup.MockMvcBuilders;
+import org.springframework.web.context.WebApplicationContext;
+
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.*;
+
+@WebMvcTest(GlobalExceptionHandler.class)
+public class GlobalExceptionHandlerTest {
+
+    @Autowired
+    private MockMvc mockMvc;
+
+    @Autowired
+    private WebApplicationContext webApplicationContext;
+
+    @BeforeEach
+    public void setup() {
+        mockMvc = MockMvcBuilders.webAppContextSetup(webApplicationContext)
+                .build();
+    }
+
+    @Test
+    public void testHandleUnexpectedExceptions() throws Exception {
+        mockMvc.perform(get("/some-endpoint-that-throws-exception"))
+                .andExpect(status().isInternalServerError())
+                .andExpect(jsonPath("$.message").value(GlobalExceptionHandler.INTERNAL_SERVER_ERROR_MESSAGE));
+    }
+}

backend/src/test/java/com/example/backend/service/ShoppingListServiceTest.java

@@ -45,13 +45,14 @@ public void getListById_shouldReturnListById() {
     }
 
     @Test
-    public void getListById_shouldReturnNullIfNotFound() {
+    public void getListById_shouldThrowNoSuchElementExceptionIfNotFound() {
         // GIVEN
         when(repository.findById("2")).thenReturn(Optional.empty());
-        // WHEN
-        ShoppingList result = service.getListById("2");
-        // THEN
-        assertNull(result);
+
+        // WHEN & THEN
+        assertThrows(NoSuchElementException.class, () -> {
+            service.getListById("2");
+        });
     }
 
     @Test