feat: custom metrics for user service

Author: EnricoBausenhart

server/user/src/main/java/meet_at_mensa/user/service/UserService.java

@@ -23,6 +23,10 @@
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+// Add Micrometer imports for Prometheus metrics
+import io.micrometer.core.instrument.Counter;
+import io.micrometer.core.instrument.MeterRegistry;
+
 @Service
 public class UserService {
 
@@ -40,6 +44,16 @@ public class UserService {
     @Autowired
     IdentityRepository identityRepository;
 
+    // Prometheus metrics
+    private final Counter usersCreatedCounter;
+
+    public UserService(MeterRegistry meterRegistry) {
+        // Initialize custom metrics
+        this.usersCreatedCounter = Counter.builder("users_created_total")
+                .description("Total number of users created")
+                .register(meterRegistry);
+    }
+
     /**
      * Searches the database for a user with id {userID}
      *
@@ -140,6 +154,7 @@ public User registerUser(UserNew userNew) {
             identityEntity = identityRepository.save(identityEntity);
             logger.info("User created successfully: {}", userEntity.getUserID());
             // throw Exception if duplicate email
+            usersCreatedCounter.increment(); // Increment the counter for user creation
         } catch (DataIntegrityViolationException e) {
             logger.error("User registration failed due to duplicate email: {}", userNew.getEmail());
             throw new UserConflictException(e.toString());
@@ -366,4 +381,13 @@ public Boolean isValidEmail(String email) {
         return email.matches(emailRegex);
     }
 
+    /**
+     * Gets the current count of users created (for testing/debugging purposes)
+     *
+     * @return current count of users created
+     */
+    public double getUsersCreatedCount() {
+        return usersCreatedCounter.count();
+    }
+
 }

server/user/src/test/java/meet_at_mensa/user/service/UserServiceMetricsTest.java

@@ -0,0 +1,122 @@
+package meet_at_mensa.user.service;
+
+import io.micrometer.core.instrument.MeterRegistry;
+import io.micrometer.core.instrument.simple.SimpleMeterRegistry;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.Mock;
+import org.mockito.junit.jupiter.MockitoExtension;
+import org.openapitools.model.UserNew;
+
+import meet_at_mensa.user.repository.UserRepository;
+import meet_at_mensa.user.repository.InterestRepository;
+import meet_at_mensa.user.repository.IdentityRepository;
+import meet_at_mensa.user.exception.UserMalformedException;
+
+import java.time.LocalDate;
+import java.util.Arrays;
+import java.util.ArrayList;
+import java.util.UUID;
+
+import static org.junit.jupiter.api.Assertions.*;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.when;
+
+@ExtendWith(MockitoExtension.class)
+public class UserServiceMetricsTest {
+
+    @Mock
+    private UserRepository userRepository;
+
+    @Mock
+    private InterestRepository interestRepository;
+
+    @Mock
+    private IdentityRepository identityRepository;
+
+    private MeterRegistry meterRegistry;
+    private UserService userService;
+
+    @BeforeEach
+    void setUp() {
+        meterRegistry = new SimpleMeterRegistry();
+        userService = new UserService(meterRegistry);
+        
+        // Inject mocked repositories using reflection for testing
+        try {
+            java.lang.reflect.Field userRepoField = UserService.class.getDeclaredField("userRepository");
+            userRepoField.setAccessible(true);
+            userRepoField.set(userService, userRepository);
+
+            java.lang.reflect.Field interestRepoField = UserService.class.getDeclaredField("interestRepository");
+            interestRepoField.setAccessible(true);
+            interestRepoField.set(userService, interestRepository);
+
+            java.lang.reflect.Field identityRepoField = UserService.class.getDeclaredField("identityRepository");
+            identityRepoField.setAccessible(true);
+            identityRepoField.set(userService, identityRepository);
+        } catch (Exception e) {
+            throw new RuntimeException("Failed to inject mocked repositories", e);
+        }
+    }
+
+    @Test
+    void testUsersCreatedCounterIncrements() {
+        // Given
+        UserNew userNew = createValidUserNew();
+        meet_at_mensa.user.model.UserEntity mockUserEntity = createMockUserEntity();
+        when(userRepository.save(any())).thenReturn(mockUserEntity);
+        when(identityRepository.save(any())).thenReturn(createMockIdentityEntity());
+        when(userRepository.findById(mockUserEntity.getUserID())).thenReturn(java.util.Optional.of(mockUserEntity));
+        when(interestRepository.findByUserID(mockUserEntity.getUserID())).thenReturn(new ArrayList<>());
+
+        // When
+        double initialCount = userService.getUsersCreatedCount();
+        userService.registerUser(userNew);
+        double finalCount = userService.getUsersCreatedCount();
+
+        // Then
+        assertEquals(1.0, finalCount - initialCount, "User creation counter should increment by 1");
+    }
+
+
+
+    @Test
+    void testMetricsAreRegistered() {
+        // Verify that the metrics are properly registered in the meter registry
+        assertNotNull(meterRegistry.find("users_created_total").counter());
+    }
+
+    private UserNew createValidUserNew() {
+        UserNew userNew = new UserNew();
+        userNew.setEmail("test@example.com");
+        userNew.setFirstname("John");
+        userNew.setLastname("Doe");
+        userNew.setBirthday(LocalDate.of(1990, 1, 1));
+        userNew.setGender("MALE");
+        userNew.setDegree("Computer Science");
+        userNew.setDegreeStart(2020);
+        userNew.setBio("Test bio");
+        userNew.setInterests(Arrays.asList("Programming", "Reading"));
+        userNew.setAuthID("auth0|123456789");
+        return userNew;
+    }
+
+    private meet_at_mensa.user.model.UserEntity createMockUserEntity() {
+        meet_at_mensa.user.model.UserEntity entity = new meet_at_mensa.user.model.UserEntity();
+        // Set required fields using reflection since they might be final
+        try {
+            java.lang.reflect.Field idField = meet_at_mensa.user.model.UserEntity.class.getDeclaredField("userID");
+            idField.setAccessible(true);
+            idField.set(entity, UUID.randomUUID());
+        } catch (Exception e) {
+            throw new RuntimeException("Failed to set user ID", e);
+        }
+        return entity;
+    }
+
+    private meet_at_mensa.user.model.IdentityEntity createMockIdentityEntity() {
+        return new meet_at_mensa.user.model.IdentityEntity(UUID.randomUUID(), "auth0|123456789");
+    }
+}