diff --git a/application/src/Domain/SourceManagement/SourceMemberInformation.php b/application/src/Domain/SourceManagement/SourceMemberInformation.php
index 6102ca3..1b52f31 100644
--- a/application/src/Domain/SourceManagement/SourceMemberInformation.php
+++ b/application/src/Domain/SourceManagement/SourceMemberInformation.php
@@ -5,9 +5,7 @@ namespace App\Domain\SourceManagement;
 use Doctrine\Common\Collections\Collection;
 use App\Entity\Source\SourceInterface;
 use Doctrine\Common\Collections\ArrayCollection;
-use App\Entity\Attribut\MemberRelationAttributInterface;
 use App\Entity\Meta\Relation\Member\MemberRelationInterface;
-use App\Entity\EntityInterface;
 
 final class SourceMemberInformation implements SourceMemberInformationInterface
 {
@@ -27,52 +25,19 @@ final class SourceMemberInformation implements SourceMemberInformationInterface
     }
 
     /**
-     * @param Collection|MemberRelationAttributInterface[] $members
+     * @param Collection|MemberRelationInterface[] $members
      */
     private function itterateOverMembers(Collection $members): void
     {
         foreach ($members as $member) {
-            if (!$this->members->contains($member)) {
-                $this->addMemberSource($member);
-                $this->itterateOverMembers($this->getMemberMembers($member));
+            if (!$this->members->contains($member->getSource())) {
+                $this->members->add($member->getSource());
+                $memberMembers = $member->getMembers();
+                $this->itterateOverMembers($memberMembers);
             }
         }
     }
 
-    /**
-     * @todo Implement tests!
-     *
-     * @deprecated The input data should be correct!
-     *
-     * @param EntityInterface $member
-     */
-    private function addMemberSource(EntityInterface $member): void
-    {
-        if ($member instanceof MemberRelationInterface) {
-            $this->members->add($member->getSource());
-        } else {
-            $this->members->add($member);
-        }
-    }
-
-    /**
-     * @todo Implement tests
-     *
-     * @deprecated The input data should be correct!
-     *
-     * @param EntityInterface $member
-     *
-     * @return Collection
-     */
-    private function getMemberMembers(EntityInterface $member): Collection
-    {
-        if ($member instanceof MemberRelationInterface) {
-            return $member->getMembers();
-        }
-
-        return $member->getMemberRelation()->getMembers();
-    }
-
     /**
      * {@inheritdoc}
      *
diff --git a/application/tests/Unit/Domain/RightManagement/RightCheckerTest.php b/application/tests/Unit/Domain/RightManagement/RightCheckerTest.php
index beda3fe..513ac46 100644
--- a/application/tests/Unit/Domain/RightManagement/RightCheckerTest.php
+++ b/application/tests/Unit/Domain/RightManagement/RightCheckerTest.php
@@ -75,7 +75,7 @@ class RightCheckerTest extends TestCase
     public function testSecondDimension(): void
     {
         $secondSource = $this->getSourceMock();
-        $this->source->getMemberRelation()->getMembers()->add($secondSource);
+        $this->source->getMemberRelation()->getMembers()->add($secondSource->getMemberRelation());
         $granted = $this->rightManager->isGranted($this->layer, $this->type, $secondSource);
         $this->assertTrue($granted);
         $notGranted = $this->rightManager->isGranted(LayerType::SOURCE, $this->type, $secondSource);
@@ -91,8 +91,8 @@ class RightCheckerTest extends TestCase
     {
         $thirdSource = $this->getSourceMock();
         $secondSource = $this->getSourceMock();
-        $secondSource->getMemberRelation()->getMembers()->add($thirdSource);
-        $this->source->getMemberRelation()->getMembers()->add($secondSource);
+        $secondSource->getMemberRelation()->getMembers()->add($thirdSource->getMemberRelation());
+        $this->source->getMemberRelation()->getMembers()->add($secondSource->getMemberRelation());
         $granted = $this->rightManager->isGranted($this->layer, $this->type, $thirdSource);
         $this->assertTrue($granted);
         $notGranted = $this->rightManager->isGranted(LayerType::SOURCE, $this->type, $thirdSource);
diff --git a/application/tests/Unit/Domain/SourceManagement/SourceMemberInformationTest.php b/application/tests/Unit/Domain/SourceManagement/SourceMemberInformationTest.php
index 6a36ba8..f27f952 100644
--- a/application/tests/Unit/Domain/SourceManagement/SourceMemberInformationTest.php
+++ b/application/tests/Unit/Domain/SourceManagement/SourceMemberInformationTest.php
@@ -11,18 +11,25 @@ use Doctrine\Common\Collections\ArrayCollection;
 use App\Entity\Source\Complex\FullPersonNameSource;
 use App\Domain\SourceManagement\SourceMemberInformation;
 use App\Domain\SourceManagement\SourceMemberInformationInterface;
+use App\Entity\Source\AbstractSource;
 
 class SourceMemberInformationTest extends TestCase
 {
     /**
      * @var SourceInterface
      */
-    protected $source;
+    private $source;
 
     /**
      * @var SourceMemberInformationInterface
      */
-    protected $sourceMemberInformation;
+    private $sourceMemberInformation;
+
+    private function createSourceMock(): SourceInterface
+    {
+        return new class() extends AbstractSource {
+        };
+    }
 
     public function setUp(): void
     {
@@ -32,7 +39,7 @@ class SourceMemberInformationTest extends TestCase
 
     public function testOneDimension(): void
     {
-        $this->source->getMemberRelation()->getMembers()->add(new TextSource());
+        $this->source->getMemberRelation()->getMembers()->add((new TextSource())->getMemberRelation());
         $allSourceMembers = $this->sourceMemberInformation->getAllMembers();
         $this->assertEquals(1, $allSourceMembers->count());
         $this->assertInstanceOf(SourceInterface::class, $allSourceMembers[0]);
@@ -42,10 +49,10 @@ class SourceMemberInformationTest extends TestCase
     {
         $source1 = new TextSource();
         $source2 = new FirstNameSource();
-        $source2->getMemberRelation()->setMembers(new ArrayCollection([$source1]));
+        $source2->getMemberRelation()->setMembers(new ArrayCollection([$source1->getMemberRelation()]));
         $source3 = new FullPersonNameSource();
-        $source3->getMemberRelation()->getMembers()->add($source2);
-        $this->source->getMemberRelation()->getMembers()->add($source3);
+        $source3->getMemberRelation()->getMembers()->add($source2->getMemberRelation());
+        $this->source->getMemberRelation()->getMembers()->add($source3->getMemberRelation());
         $allSourceMembers = $this->sourceMemberInformation->getAllMembers();
         $this->assertEquals(3, $allSourceMembers->count());
         foreach ($allSourceMembers as $sourceMember) {
@@ -56,12 +63,19 @@ class SourceMemberInformationTest extends TestCase
     public function testRecursion(): void
     {
         $recursiveSource = new UserSource();
-        $recursiveSource->getMemberRelation()->getMembers()->add($this->source);
-        $this->source->getMemberRelation()->getMembers()->add($recursiveSource);
+        $recursiveSource->getMemberRelation()->getMembers()->add($this->source->getMemberRelation());
+        $this->source->getMemberRelation()->getMembers()->add($recursiveSource->getMemberRelation());
         $allSourceMembers = $this->sourceMemberInformation->getAllMembers();
         $this->assertEquals(2, $allSourceMembers->count());
         foreach ($allSourceMembers as $sourceMember) {
             $this->assertInstanceOf(SourceInterface::class, $sourceMember);
         }
     }
+
+    public function testError(): void
+    {
+        $this->expectException(\Error::class);
+        $this->source->getMemberRelation()->getMembers()->add($this->createSourceMock());
+        $this->sourceMemberInformation->getAllMembers();
+    }
 }
diff --git a/application/tests/Unit/Domain/SourceManagement/SourceMemberManagerTest.php b/application/tests/Unit/Domain/SourceManagement/SourceMemberManagerTest.php
index 00e5705..85ba278 100644
--- a/application/tests/Unit/Domain/SourceManagement/SourceMemberManagerTest.php
+++ b/application/tests/Unit/Domain/SourceManagement/SourceMemberManagerTest.php
@@ -7,6 +7,7 @@ use App\Entity\Source\SourceInterface;
 use App\Domain\SourceManagement\SourceMemberManagerInterface;
 use App\Entity\Source\AbstractSource;
 use App\Domain\SourceManagement\SourceMemberManager;
+use App\Domain\SourceManagement\SourceMemberInformation;
 
 class SourceMemberManagerTest extends TestCase
 {
@@ -53,4 +54,17 @@ class SourceMemberManagerTest extends TestCase
         $this->assertEquals(0, $this->source->getMemberRelation()->getMemberships()->count());
         $this->assertEquals(0, $membership->getMemberRelation()->getMembers()->count());
     }
+
+    /**
+     * @todo Move this function to an own integration test class
+     */
+    public function testSourceMemberInformationIntegration(): void
+    {
+        $childSource = $this->createSource();
+        $sourceMemberInformation = new SourceMemberInformation($this->source);
+        $this->sourceMemberManager->addMember($childSource);
+        $this->assertEquals($childSource, $sourceMemberInformation->getAllMembers()->get(0));
+        $this->sourceMemberManager->removeMember($childSource);
+        $this->assertEquals(0, $sourceMemberInformation->getAllMembers()->count());
+    }
 }