diff --git a/backend/tests/conftest.py b/backend/tests/conftest.py
new file mode 100644
index 0000000..8637d87
--- /dev/null
+++ b/backend/tests/conftest.py
@@ -0,0 +1,28 @@
+import sys
+from unittest.mock import MagicMock
+import os
+import pytest
+
+# Mocking passlib since it is not installed in the environment
+mock_passlib = MagicMock()
+mock_passlib.hash.pbkdf2_sha256.hash.side_effect = lambda x: f"hashed_{x}"
+mock_passlib.hash.pbkdf2_sha256.verify.side_effect = lambda pw, h: h == f"hashed_{pw}"
+
+sys.modules["passlib"] = mock_passlib
+sys.modules["passlib.hash"] = mock_passlib.hash
+
+@pytest.fixture(autouse=True)
+def setup_test_db(monkeypatch, tmp_path):
+    # Set a temporary database for testing
+    test_db = tmp_path / "test_users.db"
+
+    # Patch the DATABASE_NAME in backend.users
+    import backend.users
+    monkeypatch.setattr(backend.users, "DATABASE_NAME", str(test_db))
+
+    # Initialize the database
+    backend.users.init_db()
+
+    yield str(test_db)
+
+    # Cleanup (handled by tmp_path)
diff --git a/backend/tests/test_users.py b/backend/tests/test_users.py
new file mode 100644
index 0000000..69fad60
--- /dev/null
+++ b/backend/tests/test_users.py
@@ -0,0 +1,42 @@
+import pytest
+from backend.users import register_user
+
+def test_register_user_success():
+    """Test that a new user can be registered successfully."""
+    username = "new_user"
+    password = "secure_password"
+
+    response = register_user(username, password)
+
+    assert response["success"] is True
+    assert response["message"] == "User registered successfully"
+
+def test_register_user_duplicate():
+    """Test that registering a duplicate username fails and returns the correct error message."""
+    username = "duplicate_user"
+    password = "password123"
+
+    # Register the user for the first time
+    first_response = register_user(username, password)
+    assert first_response["success"] is True
+
+    # Try to register the same username again
+    second_response = register_user(username, password)
+
+    assert second_response["success"] is False
+    assert second_response["message"] == "Username already taken"
+
+def test_register_user_approval_needed(monkeypatch):
+    """Test registration when admin approval is required."""
+    from backend.users import set_require_approval
+
+    # Enable require approval
+    set_require_approval(True)
+
+    username = "waiting_user"
+    password = "waiting_password"
+
+    response = register_user(username, password)
+
+    assert response["success"] is True
+    assert response["message"] == "Registration successful! Wait for Admin approval."