diff --git a/backend/.idea/workspace.xml b/backend/.idea/workspace.xml
index ec8b0d2..0590447 100644
--- a/backend/.idea/workspace.xml
+++ b/backend/.idea/workspace.xml
@@ -4,11 +4,11 @@
     <option name="autoReloadType" value="SELECTIVE" />
   </component>
   <component name="ChangeListManager">
-    <list default="true" id="3a869f59-290a-4ab2-b036-a878ce801bc4" name="Changes" comment="FindAlltasksByUser Test">
+    <list default="true" id="3a869f59-290a-4ab2-b036-a878ce801bc4" name="Changes" comment="Test TaskRepository">
+      <change afterPath="$PROJECT_DIR$/src/test/java/core/taskgroups/TaskgroupServiceTest.java" afterDir="false" />
       <change beforePath="$PROJECT_DIR$/.idea/workspace.xml" beforeDir="false" afterPath="$PROJECT_DIR$/.idea/workspace.xml" afterDir="false" />
-      <change beforePath="$PROJECT_DIR$/src/main/java/core/repositories/timemanager/TaskRepository.java" beforeDir="false" afterPath="$PROJECT_DIR$/src/main/java/core/repositories/timemanager/TaskRepository.java" afterDir="false" />
-      <change beforePath="$PROJECT_DIR$/src/test/java/core/taskgroups/TaskgroupRepsitoryTest.java" beforeDir="false" afterPath="$PROJECT_DIR$/src/test/java/core/taskgroups/TaskgroupRepsitoryTest.java" afterDir="false" />
-      <change beforePath="$PROJECT_DIR$/src/test/java/core/tasks/TaskRepositoryTest.java" beforeDir="false" afterPath="$PROJECT_DIR$/src/test/java/core/tasks/TaskRepositoryTest.java" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/pom.xml" beforeDir="false" afterPath="$PROJECT_DIR$/pom.xml" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/src/test/resources/application.properties" beforeDir="false" afterPath="$PROJECT_DIR$/src/test/resources/application.properties" afterDir="false" />
     </list>
     <option name="SHOW_DIALOG" value="false" />
     <option name="HIGHLIGHT_CONFLICTS" value="true" />
@@ -87,39 +87,7 @@
       <recent name="$PROJECT_DIR$/src/test/java/core/taskgroups" />
     </key>
   </component>
-  <component name="RunManager" selected="JUnit.TaskRepositoryTest.findAllActive">
-    <configuration name="TaskRepositoryTest.deleteAllByTaskgroup" type="JUnit" factoryName="JUnit" temporary="true" nameIsGenerated="true">
-      <module name="demo" />
-      <extension name="coverage">
-        <pattern>
-          <option name="PATTERN" value="core.tasks.*" />
-          <option name="ENABLED" value="true" />
-        </pattern>
-      </extension>
-      <option name="PACKAGE_NAME" value="core.tasks" />
-      <option name="MAIN_CLASS_NAME" value="core.tasks.TaskRepositoryTest" />
-      <option name="METHOD_NAME" value="deleteAllByTaskgroup" />
-      <option name="TEST_OBJECT" value="method" />
-      <method v="2">
-        <option name="Make" enabled="true" />
-      </method>
-    </configuration>
-    <configuration name="TaskRepositoryTest.deleteByTaskID" type="JUnit" factoryName="JUnit" temporary="true" nameIsGenerated="true">
-      <module name="demo" />
-      <extension name="coverage">
-        <pattern>
-          <option name="PATTERN" value="core.tasks.*" />
-          <option name="ENABLED" value="true" />
-        </pattern>
-      </extension>
-      <option name="PACKAGE_NAME" value="core.tasks" />
-      <option name="MAIN_CLASS_NAME" value="core.tasks.TaskRepositoryTest" />
-      <option name="METHOD_NAME" value="deleteByTaskID" />
-      <option name="TEST_OBJECT" value="method" />
-      <method v="2">
-        <option name="Make" enabled="true" />
-      </method>
-    </configuration>
+  <component name="RunManager" selected="JUnit.TaskgroupServiceTest.getTaskgroupByIDAndUsername">
     <configuration name="TaskRepositoryTest.findAllActive" type="JUnit" factoryName="JUnit" temporary="true" nameIsGenerated="true">
       <module name="demo" />
       <extension name="coverage">
@@ -168,6 +136,37 @@
         <option name="Make" enabled="true" />
       </method>
     </configuration>
+    <configuration name="TaskgroupServiceTest" type="JUnit" factoryName="JUnit" temporary="true" nameIsGenerated="true">
+      <module name="demo" />
+      <extension name="coverage">
+        <pattern>
+          <option name="PATTERN" value="core.taskgroups.*" />
+          <option name="ENABLED" value="true" />
+        </pattern>
+      </extension>
+      <option name="PACKAGE_NAME" value="core.taskgroups" />
+      <option name="MAIN_CLASS_NAME" value="core.taskgroups.TaskgroupServiceTest" />
+      <option name="TEST_OBJECT" value="class" />
+      <method v="2">
+        <option name="Make" enabled="true" />
+      </method>
+    </configuration>
+    <configuration name="TaskgroupServiceTest.getTaskgroupByIDAndUsername" type="JUnit" factoryName="JUnit" temporary="true" nameIsGenerated="true">
+      <module name="demo" />
+      <extension name="coverage">
+        <pattern>
+          <option name="PATTERN" value="core.taskgroups.*" />
+          <option name="ENABLED" value="true" />
+        </pattern>
+      </extension>
+      <option name="PACKAGE_NAME" value="core.taskgroups" />
+      <option name="MAIN_CLASS_NAME" value="core.taskgroups.TaskgroupServiceTest" />
+      <option name="METHOD_NAME" value="getTaskgroupByIDAndUsername" />
+      <option name="TEST_OBJECT" value="method" />
+      <method v="2">
+        <option name="Make" enabled="true" />
+      </method>
+    </configuration>
     <configuration name="DemoApplication" type="SpringBootApplicationConfigurationType" factoryName="Spring Boot" nameIsGenerated="true">
       <module name="demo" />
       <option name="SPRING_BOOT_MAIN_CLASS" value="core.DemoApplication" />
@@ -177,11 +176,11 @@
     </configuration>
     <recent_temporary>
       <list>
+        <item itemvalue="JUnit.TaskgroupServiceTest.getTaskgroupByIDAndUsername" />
+        <item itemvalue="JUnit.TaskgroupServiceTest" />
         <item itemvalue="JUnit.TaskRepositoryTest.findAllActive" />
         <item itemvalue="JUnit.TaskRepositoryTest.findAllUpcoming" />
         <item itemvalue="JUnit.TaskRepositoryTest.findAllOverdue" />
-        <item itemvalue="JUnit.TaskRepositoryTest.deleteByTaskID" />
-        <item itemvalue="JUnit.TaskRepositoryTest.deleteAllByTaskgroup" />
       </list>
     </recent_temporary>
   </component>
@@ -218,7 +217,7 @@
       <workItem from="1699460935890" duration="5000" />
       <workItem from="1699466564154" duration="6646000" />
       <workItem from="1699473376129" duration="1423000" />
-      <workItem from="1699639316405" duration="1997000" />
+      <workItem from="1699639316405" duration="5468000" />
     </task>
     <task id="LOCAL-00001" summary="Structure Taskgroups in Hierarchies">
       <option name="closed" value="true" />
@@ -428,14 +427,21 @@
       <option name="project" value="LOCAL" />
       <updated>1699474949938</updated>
     </task>
-    <option name="localTasksCounter" value="27" />
+    <task id="LOCAL-00027" summary="Test TaskRepository">
+      <option name="closed" value="true" />
+      <created>1699641346158</created>
+      <option name="number" value="00027" />
+      <option name="presentableId" value="LOCAL-00027" />
+      <option name="project" value="LOCAL" />
+      <updated>1699641346158</updated>
+    </task>
+    <option name="localTasksCounter" value="28" />
     <servers />
   </component>
   <component name="TypeScriptGeneratedFilesManager">
     <option name="version" value="3" />
   </component>
   <component name="VcsManagerConfiguration">
-    <MESSAGE value="Datastructure for Tasks" />
     <MESSAGE value="Implementing edit route for tasks" />
     <MESSAGE value="Delete and clear Tasks" />
     <MESSAGE value="Delete and clear Tasks (Frontend)" />
@@ -460,7 +466,8 @@
     <MESSAGE value="TaskgroupRepsitoryTest" />
     <MESSAGE value="TaskgroupRepsitoryTest (+Delete)" />
     <MESSAGE value="FindAlltasksByUser Test" />
-    <option name="LAST_COMMIT_MESSAGE" value="FindAlltasksByUser Test" />
+    <MESSAGE value="Test TaskRepository" />
+    <option name="LAST_COMMIT_MESSAGE" value="Test TaskRepository" />
   </component>
   <component name="XDebuggerManager">
     <breakpoint-manager>
@@ -491,14 +498,9 @@
           <option name="timeStamp" value="12" />
         </line-breakpoint>
         <line-breakpoint enabled="true" type="java-line">
-          <url>file://$PROJECT_DIR$/src/test/java/core/tasks/TaskRepositoryTest.java</url>
-          <line>152</line>
-          <option name="timeStamp" value="17" />
-        </line-breakpoint>
-        <line-breakpoint enabled="true" type="java-line">
-          <url>file://$PROJECT_DIR$/src/test/java/core/tasks/TaskRepositoryTest.java</url>
-          <line>151</line>
-          <option name="timeStamp" value="18" />
+          <url>file://$PROJECT_DIR$/src/test/java/core/taskgroups/TaskgroupServiceTest.java</url>
+          <line>50</line>
+          <option name="timeStamp" value="21" />
         </line-breakpoint>
       </breakpoints>
     </breakpoint-manager>
diff --git a/backend/pom.xml b/backend/pom.xml
index 8fee0eb..18787b6 100644
--- a/backend/pom.xml
+++ b/backend/pom.xml
@@ -57,9 +57,14 @@
 		<dependency>
 			<groupId>com.h2database</groupId>
 			<artifactId>h2</artifactId>
-			<version>1.3.176</version>
+			<version>2.2.224</version>
 			<scope>test</scope>
 		</dependency>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
 
 	<build>
diff --git a/backend/src/test/java/core/taskgroups/TaskgroupServiceTest.java b/backend/src/test/java/core/taskgroups/TaskgroupServiceTest.java
new file mode 100644
index 0000000..8494928
--- /dev/null
+++ b/backend/src/test/java/core/taskgroups/TaskgroupServiceTest.java
@@ -0,0 +1,68 @@
+package core.taskgroups;
+
+import core.entities.User;
+import core.entities.timemanager.Taskgroup;
+import core.repositories.UserRepository;
+import core.repositories.timemanager.TaskgroupRepository;
+import core.services.PermissionResult;
+import core.services.ServiceExitCode;
+import core.services.TaskgroupService;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.junit.runner.RunWith;
+import org.mockito.InjectMocks;
+import org.mockito.Mock;
+import org.mockito.junit.MockitoJUnitRunner;
+import org.mockito.junit.jupiter.MockitoExtension;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.autoconfigure.orm.jpa.DataJpaTest;
+import org.springframework.boot.test.autoconfigure.orm.jpa.TestEntityManager;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.test.context.jdbc.Sql;
+import org.springframework.test.context.jdbc.SqlGroup;
+import org.springframework.test.context.junit.jupiter.SpringExtension;
+
+import java.util.Optional;
+
+import static org.assertj.core.api.AssertionsForClassTypes.assertThat;
+import static org.junit.jupiter.api.Assertions.*;
+
+@SpringBootTest
+public class TaskgroupServiceTest {
+
+    @Autowired
+    private TaskgroupRepository taskgroupRepository;
+    @Autowired
+    private TaskgroupService taskgroupService;
+
+    private static final String username = "Testuser1";
+    @Test
+    @SqlGroup({
+            @Sql("classpath:taskgroupRepositoryTestEntries.sql"),
+            @Sql("classpath:taskRepositoryEntries.sql")
+    })
+    void getTaskgroupByIDAndUsername() {
+        //Situation 1: correct taskgroup and username
+        assertFalse(taskgroupRepository.findById(1L).isEmpty());
+
+        PermissionResult<Taskgroup> permissionResult = taskgroupService.getTaskgroupByIDAndUsername(1L, username);
+        assertThat(permissionResult).isNotNull();
+        assertTrue(permissionResult.isHasPermissions());
+        assertEquals(ServiceExitCode.OK, permissionResult.getExitCode());
+        assertEquals(taskgroupRepository.findById(1L).get(), permissionResult.getResult());
+
+        //Situation 2: invalid taskgroup
+        PermissionResult<Taskgroup> invalid_group = taskgroupService.getTaskgroupByIDAndUsername(-1L, username);
+        assertThat(invalid_group).isNotNull();
+        assertEquals(ServiceExitCode.MISSING_ENTITY, invalid_group.getExitCode());
+        assertFalse(invalid_group.isHasPermissions());
+
+        //Situation 3: invalid user
+        PermissionResult<Taskgroup> invalid_user = taskgroupService.getTaskgroupByIDAndUsername(1L, "Rotzbakke");
+        assertThat(invalid_user).isNotNull();
+        assertEquals(ServiceExitCode.OK, invalid_user.getExitCode());
+        assertFalse(invalid_user.isHasPermissions());
+    }
+
+}
diff --git a/backend/src/test/resources/application.properties b/backend/src/test/resources/application.properties
index 04ae4dc..512dbe3 100644
--- a/backend/src/test/resources/application.properties
+++ b/backend/src/test/resources/application.properties
@@ -1,6 +1,12 @@
 spring.datasource.driverClassName=org.h2.Driver
 spring.datasource.url=jdbc:h2:file:~/testdb;MODE=LEGACY
+spring.jpa.database-platform=org.hibernate.dialect.H2Dialect
 spring.h2.console.enabled=true
 spring.h2.console.path=/console
 spring.flyway.enabled=false
-spring.liquibase.enabled=false
\ No newline at end of file
+spring.liquibase.enabled=false
+
+demo.webapp.jwtSecret=demoWebappSecretKey
+demo.webapp.jwtExpirationMS=86400000
+spring.sql.init.mode=always
+spring.jpa.hibernate.ddl-auto=create-drop
\ No newline at end of file