import os, sys; sys.path.insert(0, os.path.abspath(os.path.join(os.path.dirname(__file__), "..")))
import torch
from bit_transformer.model import BitTransformerLM


def test_act_halting():
    model = BitTransformerLM(
        d_model=16,
        nhead=2,
        num_layers=3,
        dim_feedforward=32,
        max_seq_len=8,
        use_act=True,
        act_threshold=0.1,
    )
    bits = torch.randint(0, 2, (1, 8), dtype=torch.long)
    _, telemetry = model(bits)
    halt_probs = torch.stack(telemetry["halt_probs"])[:, 0, 0]
    assert (halt_probs < 1).sum().item() < model.num_layers