diff --git a/test/teos/unit/test_appointments_dbm.py b/test/teos/unit/test_appointments_dbm.py
index b6cd69f..48928f6 100644
--- a/test/teos/unit/test_appointments_dbm.py
+++ b/test/teos/unit/test_appointments_dbm.py
@@ -169,15 +169,32 @@ def test_delete_locator_map(db_manager):
     assert len(locator_maps) != 0
 
     for locator, uuids in locator_maps.items():
-        db_manager.delete_locator_map(locator)
+        assert db_manager.delete_locator_map(locator) is True
 
     locator_maps = db_manager.load_appointments_db(prefix=LOCATOR_MAP_PREFIX)
     assert len(locator_maps) == 0
 
+    # Keys of wrong type should fail
+    assert db_manager.delete_locator_map(42) is False
+
+
+def test_store_watcher_appointment_wrong(db_manager, watcher_appointments):
+    # Wrong uuid types should fail
+    for _, appointment in watcher_appointments.items():
+        assert db_manager.store_watcher_appointment(42, appointment.to_dict()) is False
+
+
+def test_load_watcher_appointment_wrong(db_manager):
+    # Random keys should fail
+    assert db_manager.load_watcher_appointment(get_random_value_hex(16)) is None
+
+    # Wrong format keys should also return None
+    assert db_manager.load_watcher_appointment(42) is None
+
 
 def test_store_load_watcher_appointment(db_manager, watcher_appointments):
     for uuid, appointment in watcher_appointments.items():
-        db_manager.store_watcher_appointment(uuid, appointment.to_dict())
+        assert db_manager.store_watcher_appointment(uuid, appointment.to_dict()) is True
 
     db_watcher_appointments = db_manager.load_watcher_appointments()
 
@@ -200,7 +217,7 @@ def test_store_load_triggered_appointment(db_manager):
     # Create an appointment flagged as triggered
     triggered_appointment, _ = generate_dummy_appointment(real_height=False)
     uuid = uuid4().hex
-    db_manager.store_watcher_appointment(uuid, triggered_appointment.to_dict())
+    assert db_manager.store_watcher_appointment(uuid, triggered_appointment.to_dict()) is True
     db_manager.create_triggered_appointment_flag(uuid)
 
     # The new appointment is grabbed only if we set include_triggered
@@ -208,9 +225,23 @@ def test_store_load_triggered_appointment(db_manager):
     assert uuid in db_manager.load_watcher_appointments(include_triggered=True)
 
 
+def test_store_responder_trackers_wrong(db_manager, responder_trackers):
+    # Wrong uuid types should fail
+    for _, tracker in responder_trackers.items():
+        assert db_manager.store_responder_tracker(42, {"value": tracker}) is False
+
+
+def test_load_responder_tracker_wrong(db_manager):
+    # Random keys should fail
+    assert db_manager.load_responder_tracker(get_random_value_hex(16)) is None
+
+    # Wrong format keys should also return None
+    assert db_manager.load_responder_tracker(42) is None
+
+
 def test_store_load_responder_trackers(db_manager, responder_trackers):
     for key, value in responder_trackers.items():
-        db_manager.store_responder_tracker(key, {"value": value})
+        assert db_manager.store_responder_tracker(key, {"value": value}) is True
 
     db_responder_trackers = db_manager.load_responder_trackers()
 
@@ -226,16 +257,19 @@ def test_delete_watcher_appointment(db_manager, watcher_appointments):
     assert len(db_watcher_appointments) != 0
 
     for key in watcher_appointments.keys():
-        db_manager.delete_watcher_appointment(key)
+        assert db_manager.delete_watcher_appointment(key) is True
 
     db_watcher_appointments = db_manager.load_watcher_appointments()
     assert len(db_watcher_appointments) == 0
 
+    # Keys of wrong type should fail
+    assert db_manager.delete_watcher_appointment(42) is False
+
 
 def test_batch_delete_watcher_appointments(db_manager, watcher_appointments):
     # Let's start by adding a bunch of appointments
     for uuid, appointment in watcher_appointments.items():
-        db_manager.store_watcher_appointment(uuid, appointment.to_dict())
+        assert db_manager.store_watcher_appointment(uuid, appointment.to_dict()) is True
 
     first_half = list(watcher_appointments.keys())[: len(watcher_appointments) // 2]
     second_half = list(watcher_appointments.keys())[len(watcher_appointments) // 2 :]
@@ -261,16 +295,19 @@ def test_delete_responder_tracker(db_manager, responder_trackers):
     assert len(db_responder_trackers) != 0
 
     for key in responder_trackers.keys():
-        db_manager.delete_responder_tracker(key)
+        assert db_manager.delete_responder_tracker(key) is True
 
     db_responder_trackers = db_manager.load_responder_trackers()
     assert len(db_responder_trackers) == 0
 
+    # Keys of wrong type should fail
+    assert db_manager.delete_responder_tracker(42) is False
+
 
 def test_batch_delete_responder_trackers(db_manager, responder_trackers):
     # Let's start by adding a bunch of appointments
     for uuid, value in responder_trackers.items():
-        db_manager.store_responder_tracker(uuid, {"value": value})
+        assert db_manager.store_responder_tracker(uuid, {"value": value}) is True
 
     first_half = list(responder_trackers.keys())[: len(responder_trackers) // 2]
     second_half = list(responder_trackers.keys())[len(responder_trackers) // 2 :]
@@ -293,22 +330,28 @@ def test_batch_delete_responder_trackers(db_manager, responder_trackers):
 def test_store_load_last_block_hash_watcher(db_manager):
     # Let's first create a made up block hash
     local_last_block_hash = get_random_value_hex(32)
-    db_manager.store_last_block_hash_watcher(local_last_block_hash)
+    assert db_manager.store_last_block_hash_watcher(local_last_block_hash) is True
 
     db_last_block_hash = db_manager.load_last_block_hash_watcher()
 
     assert local_last_block_hash == db_last_block_hash
 
+    # Wrong types for last block should fail for both store and load
+    assert db_manager.store_last_block_hash_watcher(42) is False
+
 
 def test_store_load_last_block_hash_responder(db_manager):
     # Same for the responder
     local_last_block_hash = get_random_value_hex(32)
-    db_manager.store_last_block_hash_responder(local_last_block_hash)
+    assert db_manager.store_last_block_hash_responder(local_last_block_hash) is True
 
     db_last_block_hash = db_manager.load_last_block_hash_responder()
 
     assert local_last_block_hash == db_last_block_hash
 
+    # Wrong types for last block should fail for both store and load
+    assert db_manager.store_last_block_hash_responder(42) is False
+
 
 def test_create_triggered_appointment_flag(db_manager):
     # Test that flags are added
@@ -354,12 +397,15 @@ def test_delete_triggered_appointment_flag(db_manager):
 
     # Delete all entries
     for k in keys:
-        db_manager.delete_triggered_appointment_flag(k)
+        assert db_manager.delete_triggered_appointment_flag(k) is True
 
     # Try to load them back
     for k in keys:
         assert db_manager.db.get((TRIGGERED_APPOINTMENTS_PREFIX + k).encode("utf-8")) is None
 
+    # Keys of wrong type should fail
+    assert db_manager.delete_triggered_appointment_flag(42) is False
+
 
 def test_batch_delete_triggered_appointment_flag(db_manager):
     # Let's add some flags first
diff --git a/test/teos/unit/test_users_dbm.py b/test/teos/unit/test_users_dbm.py
new file mode 100644
index 0000000..5066561
--- /dev/null
+++ b/test/teos/unit/test_users_dbm.py
@@ -0,0 +1,82 @@
+from teos.appointments_dbm import AppointmentsDBM
+
+from test.teos.unit.conftest import get_random_value_hex
+
+
+stored_users = {}
+
+
+def open_create_db(db_path):
+
+    try:
+        db_manager = AppointmentsDBM(db_path)
+
+        return db_manager
+
+    except ValueError:
+        return False
+
+
+def test_store_user(user_db_manager):
+    # Store user should work as long as the user_pk is properly formatted and data is a dictionary
+    user_pk = "02" + get_random_value_hex(32)
+    user_data = {"available_slots": 42}
+    stored_users[user_pk] = user_data
+    assert user_db_manager.store_user(user_pk, user_data) is True
+
+    # Wrong pks should return False on adding
+    user_pk = "04" + get_random_value_hex(32)
+    user_data = {"available_slots": 42}
+    assert user_db_manager.store_user(user_pk, user_data) is False
+
+    # Same for wrong types
+    assert user_db_manager.store_user(42, user_data) is False
+
+    # And for wrong type user data
+    assert user_db_manager.store_user(user_pk, 42) is False
+
+
+def test_load_user(user_db_manager):
+    # Loading a user we have stored should work
+    for user_pk, user_data in stored_users.items():
+        assert user_db_manager.load_user(user_pk) == user_data
+
+    # Random keys should fail
+    assert user_db_manager.load_user(get_random_value_hex(33)) is None
+
+    # Wrong format keys should also return None
+    assert user_db_manager.load_user(42) is None
+
+
+def test_delete_user(user_db_manager):
+    # Deleting an existing user should work
+    for user_pk, user_data in stored_users.items():
+        assert user_db_manager.delete_user(user_pk) is True
+
+    for user_pk, user_data in stored_users.items():
+        assert user_db_manager.load_user(user_pk) is None
+
+    # But deleting a non existing one should not fail
+    assert user_db_manager.delete_user(get_random_value_hex(32)) is True
+
+    # Keys of wrong type should fail
+    assert user_db_manager.delete_user(42) is False
+
+
+def test_load_all_users(user_db_manager):
+    # There should be no users at the moment
+    assert user_db_manager.load_all_users() == {}
+    stored_users = {}
+
+    # Adding some and checking we get them all
+    for i in range(10):
+        user_pk = "02" + get_random_value_hex(32)
+        user_data = {"available_slots": i}
+        user_db_manager.store_user(user_pk, user_data)
+        stored_users[user_pk] = user_data
+
+    all_users = user_db_manager.load_all_users()
+
+    assert set(all_users.keys()) == set(stored_users.keys())
+    for k, v in all_users.items():
+        assert stored_users[k] == v