diff --git a/backend/src/test/java/dev/ksan/etfoglasiserver/service/JWTServiceTest.java b/backend/src/test/java/dev/ksan/etfoglasiserver/service/JWTServiceTest.java
index cb2b536..640afe4 100644
--- a/backend/src/test/java/dev/ksan/etfoglasiserver/service/JWTServiceTest.java
+++ b/backend/src/test/java/dev/ksan/etfoglasiserver/service/JWTServiceTest.java
@@ -1,47 +1,49 @@
 package dev.ksan.etfoglasiserver.service;
 
+import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.junit.jupiter.MockitoExtension;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.test.context.SpringBootTest;
-import org.springframework.security.core.userdetails.UserDetails;
 import org.springframework.test.context.TestPropertySource;
 
+import java.lang.reflect.Field;
+
 import static org.assertj.core.api.AssertionsForClassTypes.assertThat;
 import static org.assertj.core.api.AssertionsForClassTypes.assertThatThrownBy;
 
-@SpringBootTest
-@TestPropertySource(locations = "classpath:application.properties")
+@ExtendWith(MockitoExtension.class)
 class JWTServiceTest {
 
-    @Autowired
-    JWTService jwtService;
+    private JWTService jwtService;
 
-    private org.springframework.security.core.userdetails.UserDetails userDetails(String email) {
-        return org.springframework.security.core.userdetails.User
-                .withUsername(email)
-                .password("irrelevant")
-                .roles("USER")
-                .build();
+    private static final String TEST_SECRET =
+            "dGVzdHNlY3JldGtleXRoYXRpc2xvbmdlbm91Z2hmb3JibWFjc2hhMjU2dGVzdGtleQ==";
+
+    @BeforeEach
+    void setUp() throws Exception {
+        jwtService = new JWTService();
+        Field secret = JWTService.class.getDeclaredField("secretKey");
+        secret.setAccessible(true);
+        secret.set(jwtService, TEST_SECRET);
     }
 
     @Test
     void generateToken_extractEmail_returnsCorrectEmail() {
         String token = jwtService.generateToken("alice@example.com");
-
         assertThat(jwtService.extractEmail(token)).isEqualTo("alice@example.com");
     }
 
     @Test
     void validateToken_correctUser_returnsTrue() {
         String token = jwtService.generateToken("alice@example.com");
-
         assertThat(jwtService.validateToken(token, userDetails("alice@example.com"))).isTrue();
     }
 
     @Test
     void validateToken_differentUser_returnsFalse() {
         String token = jwtService.generateToken("alice@example.com");
-
         assertThat(jwtService.validateToken(token, userDetails("bob@example.com"))).isFalse();
     }
 
@@ -49,8 +51,12 @@ class JWTServiceTest {
     void validateToken_tamperedToken_throwsException() {
         String token = jwtService.generateToken("alice@example.com");
         String tampered = token.substring(0, token.length() - 4) + "XXXX";
-
         assertThatThrownBy(() -> jwtService.validateToken(tampered, userDetails("alice@example.com")))
                 .isInstanceOf(Exception.class);
     }
+
+    private org.springframework.security.core.userdetails.UserDetails userDetails(String email) {
+        return org.springframework.security.core.userdetails.User
+                .withUsername(email).password("x").roles("USER").build();
+    }
 }
\ No newline at end of file
diff --git a/backend/src/test/resources/application.properties b/backend/src/test/resources/application-test.properties
similarity index 100%
rename from backend/src/test/resources/application.properties
rename to backend/src/test/resources/application-test.properties