diff --git a/build.gradle.kts b/build.gradle.kts
index 43b637e..95f3b94 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -86,6 +86,9 @@ dependencies {
     testImplementation("org.testcontainers:postgresql:1.19.8")
     testImplementation("com.github.dasniko:testcontainers-keycloak:3.3.1")
     testImplementation("org.testcontainers:junit-jupiter:1.19.8")
+    // mockK
+    testImplementation("io.mockk:mockk:1.13.11")
+
 }
 
 springBoot {
diff --git a/src/main/kotlin/org/jaqpot/api/auth/keycloak/KeycloakConfig.kt b/src/main/kotlin/org/jaqpot/api/auth/keycloak/KeycloakConfig.kt
index 3150025..5c9ed6a 100644
--- a/src/main/kotlin/org/jaqpot/api/auth/keycloak/KeycloakConfig.kt
+++ b/src/main/kotlin/org/jaqpot/api/auth/keycloak/KeycloakConfig.kt
@@ -4,8 +4,8 @@ import org.springframework.boot.context.properties.ConfigurationProperties
 
 @ConfigurationProperties(prefix = "keycloak")
 data class KeycloakConfig(
-    val serverUrl: String = "",
-    var realm: String = "",
-    var clientId: String = "",
-    var clientSecret: String = "",
+    val serverUrl: String,
+    var realm: String,
+    var clientId: String,
+    var clientSecret: String,
 )
diff --git a/src/test/kotlin/org/jaqpot/api/auth/keycloak/KeycloakUserServiceTest.kt b/src/test/kotlin/org/jaqpot/api/auth/keycloak/KeycloakUserServiceTest.kt
new file mode 100644
index 0000000..e7bbd92
--- /dev/null
+++ b/src/test/kotlin/org/jaqpot/api/auth/keycloak/KeycloakUserServiceTest.kt
@@ -0,0 +1,64 @@
+package org.jaqpot.api.auth.keycloak
+
+import io.mockk.every
+import io.mockk.mockk
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.BeforeEach
+import org.junit.jupiter.api.Test
+import org.keycloak.admin.client.Keycloak
+import org.keycloak.representations.idm.UserRepresentation
+import org.springframework.test.util.ReflectionTestUtils
+
+class KeycloakUserServiceTest {
+
+    private val keycloakConfig = KeycloakConfig(
+        "serverUrl",
+        "realm",
+        "clientId",
+        "clientSecret",
+    )
+
+    private val userRepresentation: UserRepresentation = mockk()
+
+    private lateinit var keycloakClient: Keycloak
+    private lateinit var keycloakUserService: KeycloakUserService
+
+    @BeforeEach
+    fun setup() {
+        every { userRepresentation.id } returns "id"
+        every { userRepresentation.firstName } returns "firstName"
+        every { userRepresentation.lastName } returns "lastName"
+        keycloakClient = mockk()
+        keycloakUserService = KeycloakUserService(keycloakConfig)
+        ReflectionTestUtils.setField(keycloakUserService, "keycloakClient", keycloakClient)
+    }
+
+    @Test
+    fun getUserById() {
+        every { keycloakClient.realm("realm").users().get("id").toRepresentation() } returns userRepresentation
+        val user = keycloakUserService.getUserById("id")
+
+        assertEquals(user.name, "firstName lastName")
+
+    }
+
+    @Test
+    fun getUserByUsername() {
+        every {
+            keycloakClient.realm("realm").users().searchByUsername("username", true)
+        } returns listOf(userRepresentation)
+        val user = keycloakUserService.getUserByUsername("username")
+
+        assertEquals(user.name, "firstName lastName")
+    }
+
+    @Test
+    fun getUserByEmail() {
+        every {
+            keycloakClient.realm("realm").users().searchByEmail("email", true)
+        } returns listOf(userRepresentation)
+        val user = keycloakUserService.getUserByEmail("email")
+
+        assertEquals(user.name, "firstName lastName")
+    }
+}