simpo-unit-test-execution

name	simpo-unit-test-execution
description	How to correctly run the SimPO unit test to generate the loss.npz output file with reproducible results. Use when executing the unit test after implementing the loss function.

Running the SimPO Unit Test

Prerequisites

• Python 3.10 environment is active
• simpo_loss function is correctly implemented in /root/SimPO/scripts/simpo_trainer.py
• All dependencies (torch, transformers, trl, accelerate, etc.) are installed

Execution Steps

# 1. Ensure correct Python
source /root/SimPO/.venv/bin/activate  # or however the venv is activated
python -VV  # Must show Python 3.10.x

# 2. Run the unit test (DO NOT modify unit_test_1.py)
cd /root/SimPO
python unit_test/unit_test_1.py

# 3. Verify output exists
python -c "import numpy as np; data = np.load('/root/loss.npz'); print('losses:', data['losses'])"

# 4. Generate the python info file
python -VV > /root/python_info.txt 2>&1
python -m pip freeze >> /root/python_info.txt

What the Unit Test Does

The unit test:

1. Creates fixed input tensors for policy_chosen_logps and policy_rejected_logps
2. Creates a SimPOTrainer (or mock) with specific beta and gamma values
3. Calls simpo_loss() with those fixed inputs
4. Saves the resulting losses to /root/loss.npz with key 'losses'

Verifying Correctness

The SimPO loss with sigmoid loss type should compute:

losses = -log(sigmoid(beta * (chosen_avg_logps - rejected_avg_logps - gamma)))

If the test provides specific beta and gamma values, you can manually verify:

import torch
import torch.nn.functional as F

# Example verification
logits = policy_chosen_logps - policy_rejected_logps - gamma
losses = -F.logsigmoid(beta * logits)

Important Notes

• Do NOT modify unit_test_1.py — it has fixed inputs for reproducibility
• The loss output must be deterministic (no randomness involved)
• Make sure self.accelerator.device is handled correctly; the unit test may mock or provide this
• If the unit test creates a minimal/mock trainer, ensure your simpo_loss method works with it