def test_detect(monkeypatch):
    """Test the detection of an MPI environment configuration."""
    monkeypatch.setattr(lightning.fabric.plugins.environments.mpi, "_MPI4PY_AVAILABLE", False)
    assert not MPIEnvironment.detect()

    # pretend mpi4py is available
    monkeypatch.setattr(lightning.fabric.plugins.environments.mpi, "_MPI4PY_AVAILABLE", True)
    mpi4py_mock = MagicMock()

    with mock.patch.dict("sys.modules", {"mpi4py": mpi4py_mock}):
        mpi4py_mock.MPI.COMM_WORLD.Get_size.return_value = 0
        assert not MPIEnvironment.detect()

        mpi4py_mock.MPI.COMM_WORLD.Get_size.return_value = 1
        assert not MPIEnvironment.detect()

        mpi4py_mock.MPI.COMM_WORLD.Get_size.return_value = 2
        assert MPIEnvironment.detect()
Test the detection of an MPI environment configuration.
tests/tests_fabric/plugins/environments/test_mpi.py