diff --git a/app/proprietary/src/test/java/stirling/software/proprietary/model/TeamTest.java b/app/proprietary/src/test/java/stirling/software/proprietary/model/TeamTest.java
new file mode 100644
index 000000000..82e564bae
--- /dev/null
+++ b/app/proprietary/src/test/java/stirling/software/proprietary/model/TeamTest.java
@@ -0,0 +1,74 @@
+package stirling.software.proprietary.model;
+
+import static org.junit.jupiter.api.Assertions.*;
+import static org.mockito.Mockito.*;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.junit.jupiter.MockitoExtension;
+
+import stirling.software.proprietary.security.model.User;
+
+@ExtendWith(MockitoExtension.class)
+class TeamTest {
+
+    @Test
+    void users_isInitializedAndEmpty() {
+        Team team = new Team();
+        assertNotNull(team.getUsers(), "users Set should be initialized");
+        assertTrue(team.getUsers().isEmpty(), "users Set should start empty");
+    }
+
+    @Test
+    void addUser_addsToSet_and_setsBackReference() {
+        Team team = new Team();
+        User user = mock(User.class);
+
+        team.addUser(user);
+
+        assertTrue(team.getUsers().contains(user), "Team should contain added user");
+        verify(user, times(1)).setTeam(team);
+        verifyNoMoreInteractions(user);
+    }
+
+    @Test
+    void addUser_twice_isIdempotent_dueToSetSemantics() {
+        Team team = new Team();
+        User user = mock(User.class);
+
+        team.addUser(user);
+        team.addUser(user);
+
+        assertEquals(1, team.getUsers().size(), "Adding same user twice should not duplicate");
+        // In our code, setTeam is called twice (we only test Set idempotency)
+        verify(user, times(2)).setTeam(team);
+    }
+
+    @Test
+    void removeUser_removesFromSet_and_clearsBackReference() {
+        Team team = new Team();
+        User user = mock(User.class);
+
+        team.addUser(user);
+        assertTrue(team.getUsers().contains(user));
+
+        team.removeUser(user);
+
+        assertFalse(team.getUsers().contains(user), "User should be removed from Team");
+        verify(user, times(1)).setTeam(null);
+    }
+
+    @Test
+    void removeUser_onUserNotInSet_still_clearsBackReference() {
+        Team team = new Team();
+        User stranger = mock(User.class);
+
+        // not added
+        team.removeUser(stranger);
+
+        // Set remains empty
+        assertTrue(team.getUsers().isEmpty());
+        // Back-reference is still set to null
+        verify(stranger, times(1)).setTeam(null);
+    }
+}