diff --git a/backend/src/routes/test_projects.py b/backend/src/routes/test_projects.py
index af49ab8..9230057 100644
--- a/backend/src/routes/test_projects.py
+++ b/backend/src/routes/test_projects.py
@@ -26,11 +26,12 @@ def test_project_get(client: TestClient, session: Session):
     project = Project(name="Uni", creation_date=datetime.now())
     session.add(project)
     session.commit()
+    session.refresh(project)
     # Request data from API
-    response = client.get("/projects/Uni")
+    response = client.get(f"/projects/{project.id}")
     response_data = response.json()
     assert response.status_code == status.HTTP_200_OK
-    assert response_data["id"]  # Not empty?
+    assert response_data["id"] == project.id
     assert response_data["name"] == project.name
     assert response_data["creation_date"] == project.creation_date.isoformat()
 
@@ -40,12 +41,13 @@ def test_project_update(client: TestClient, session: Session):
     project = Project(name="Uni", creation_date=datetime.now())
     session.add(project)
     session.commit()
+    session.refresh(project)
     # Perform update via API
     project_updates = {"name": "UNI"}
-    response = client.patch("/projects/Uni", json=project_updates)
+    response = client.patch(f"/projects/{project.id}", json=project_updates)
     response_data = response.json()
     assert response.status_code == status.HTTP_200_OK
-    assert response_data["id"]  # Not empty?
+    assert response_data["id"] == project.id
     assert response_data["name"] == project_updates["name"]
     assert response_data["creation_date"] == project.creation_date.isoformat()
 
@@ -55,21 +57,22 @@ def test_project_delete(client: TestClient, session: Session):
     project = Project(name="Uni", creation_date=datetime.now())
     session.add(project)
     session.commit()
+    session.refresh(project)
     # Delete via API
-    response = client.delete("/projects/Uni")
-    response_data = response.json()
+    response = client.delete(f"/projects/{project.id}")
     assert response.status_code == status.HTTP_204_NO_CONTENT
     assert session.exec(select(Project).where(Project.name == "Uni")).first() is None  # Element deleted from database?
 
 
 def test_project_get_list(client: TestClient, session: Session):
-    pass
     # Fill database
     project_uni = Project(name="Uni", creation_date=datetime.now())
     project_sport = Project(name="Sport", creation_date=datetime.now())
     session.add(project_uni)
     session.add(project_sport)
     session.commit()
+    session.refresh(project_uni)
+    session.refresh(project_sport)
     # Request data from API
     response = client.get("/projects/")
     response_data = response.json()
@@ -77,9 +80,9 @@ def test_project_get_list(client: TestClient, session: Session):
     assert len(response_data) == 2
 
     assert response_data[0]["name"] == project_uni.name
-    assert response_data[0]["id"]  # Not empty?
+    assert response_data[0]["id"] == project_uni.id
     assert response_data[0]["creation_date"] == project_uni.creation_date.isoformat()
 
     assert response_data[1]["name"] == project_sport.name
-    assert response_data[1]["id"]  # Not empty?
+    assert response_data[1]["id"] == project_sport.id
     assert response_data[1]["creation_date"] == project_sport.creation_date.isoformat()
diff --git a/backend/src/routes/test_tags.py b/backend/src/routes/test_tags.py
index c8fbc52..69f99e9 100644
--- a/backend/src/routes/test_tags.py
+++ b/backend/src/routes/test_tags.py
@@ -21,11 +21,13 @@ def test_tag_get(client: TestClient, session: Session):
     tag = Tag(name="Uni")
     session.add(tag)
     session.commit()
+    session.refresh(tag)
     # Request data from API
-    response = client.get("/tags/Uni")
+    print(f"get tag {tag.id}")
+    response = client.get(f"/tags/{tag.id}")
     response_data = response.json()
     assert response.status_code == status.HTTP_200_OK
-    assert response_data["id"]  # Not empty?
+    assert response_data["id"] == tag.id
     assert response_data["name"] == tag.name
 
 
@@ -34,12 +36,13 @@ def test_tag_update(client: TestClient, session: Session):
     tag = Tag(name="Uni")
     session.add(tag)
     session.commit()
+    session.refresh(tag)
     # Perform update via API
     tag_updates = {"name": "UNI"}
-    response = client.patch("/tags/Uni", json=tag_updates)
+    response = client.patch(f"/tags/{tag.id}", json=tag_updates)
     response_data = response.json()
     assert response.status_code == status.HTTP_200_OK
-    assert response_data["id"]  # Not empty?
+    assert response_data["id"] == tag.id
     assert response_data["name"] == tag_updates["name"]
 
 
@@ -48,21 +51,22 @@ def test_tag_delete(client: TestClient, session: Session):
     tag = Tag(name="Uni")
     session.add(tag)
     session.commit()
+    session.refresh(tag)
     # Delete via API
-    response = client.delete("/tags/Uni")
-    response_data = response.json()
+    response = client.delete(f"/tags/{tag.id}")
     assert response.status_code == status.HTTP_204_NO_CONTENT
     assert session.exec(select(Tag).where(Tag.name == "Uni")).first() is None  # Element deleted from database?
 
 
 def test_tag_get_list(client: TestClient, session: Session):
-    pass
     # Fill database
     tag_uni = Tag(name="Uni", creation_date=datetime.now())
     tag_sport = Tag(name="Sport", creation_date=datetime.now())
     session.add(tag_uni)
     session.add(tag_sport)
     session.commit()
+    session.refresh(tag_uni)
+    session.refresh(tag_sport)
     # Request data from API
     response = client.get("/tags/")
     response_data = response.json()
@@ -70,7 +74,7 @@ def test_tag_get_list(client: TestClient, session: Session):
     assert len(response_data) == 2
 
     assert response_data[0]["name"] == tag_uni.name
-    assert response_data[0]["id"]  # Not empty?
+    assert response_data[0]["id"] == tag_uni.id
 
     assert response_data[1]["name"] == tag_sport.name
-    assert response_data[1]["id"]  # Not empty?
+    assert response_data[1]["id"] == tag_sport.id