ultralytics/tests/test_engine.py
Glenn Jocher 79b2086bfd
ultralytics 8.4.45 Fix pretrained checkpoint training regression (#24378)
Co-authored-by: UltralyticsAssistant <web@ultralytics.com>
2026-04-29 17:15:40 +02:00

236 lines
8.6 KiB
Python

# Ultralytics 🚀 AGPL-3.0 License - https://ultralytics.com/license
import sys
from types import SimpleNamespace
from unittest import mock
import pytest
import torch
from tests import MODEL, SOURCE, TASK_MODEL_DATA
from ultralytics import YOLO
from ultralytics.cfg import get_cfg
from ultralytics.engine.exporter import Exporter
from ultralytics.engine.trainer import BaseTrainer
from ultralytics.models.yolo import classify, detect, obb, pose, segment
from ultralytics.nn.tasks import load_checkpoint
from ultralytics.utils import ASSETS, DEFAULT_CFG, WEIGHTS_DIR
def test_func(*args, **kwargs):
"""Test function used as a callback stub to verify callback registration."""
print("callback test passed")
def test_export():
"""Test model exporting functionality by adding a callback and verifying its execution."""
exporter = Exporter()
exporter.add_callback("on_export_start", test_func)
assert test_func in exporter.callbacks["on_export_start"], "on_export_start callback not registered"
f = exporter(model=YOLO("yolo26n.yaml").model)
YOLO(f)(SOURCE) # exported model inference
@pytest.mark.parametrize(
"trainer_cls,validator_cls,predictor_cls,data,model,weights",
[
(
detect.DetectionTrainer,
detect.DetectionValidator,
detect.DetectionPredictor,
"coco8.yaml",
"yolo26n.yaml",
MODEL,
),
(
segment.SegmentationTrainer,
segment.SegmentationValidator,
segment.SegmentationPredictor,
"coco8-seg.yaml",
"yolo26n-seg.yaml",
WEIGHTS_DIR / "yolo26n-seg.pt",
),
(
classify.ClassificationTrainer,
classify.ClassificationValidator,
classify.ClassificationPredictor,
"imagenet10",
"yolo26n-cls.yaml",
None,
),
(obb.OBBTrainer, obb.OBBValidator, obb.OBBPredictor, "dota8.yaml", "yolo26n-obb.yaml", None),
(pose.PoseTrainer, pose.PoseValidator, pose.PosePredictor, "coco8-pose.yaml", "yolo26n-pose.yaml", None),
],
)
def test_task(trainer_cls, validator_cls, predictor_cls, data, model, weights):
"""Test YOLO training, validation, and prediction for various tasks."""
overrides = {
"data": data,
"model": model,
"imgsz": 32,
"epochs": 1,
"save": False,
"mask_ratio": 1,
"overlap_mask": False,
}
# Trainer
trainer = trainer_cls(overrides=overrides)
trainer.add_callback("on_train_start", test_func)
assert test_func in trainer.callbacks["on_train_start"], "on_train_start callback not registered"
trainer.train()
# Validator
cfg = get_cfg(DEFAULT_CFG)
cfg.data = data
cfg.imgsz = 32
val = validator_cls(args=cfg)
val.add_callback("on_val_start", test_func)
assert test_func in val.callbacks["on_val_start"], "on_val_start callback not registered"
val(model=trainer.best)
# Predictor
pred = predictor_cls(overrides={"imgsz": [64, 64]})
pred.add_callback("on_predict_start", test_func)
assert test_func in pred.callbacks["on_predict_start"], "on_predict_start callback not registered"
# Determine model path for prediction
model_path = weights if weights else trainer.best
if model == "yolo26n.yaml": # only for detection
# Confirm there is no issue with sys.argv being empty
with mock.patch.object(sys, "argv", []):
result = pred(source=ASSETS, model=model_path)
assert len(result) > 0, f"Predictor returned no results for {model}"
else:
result = pred(source=ASSETS, model=model_path)
assert len(result) > 0, f"Predictor returned no results for {model}"
# Test resume functionality
with pytest.raises(AssertionError):
trainer_cls(overrides={**overrides, "resume": trainer.last}).train()
@pytest.mark.parametrize("task,weight,data", TASK_MODEL_DATA)
def test_resume_incomplete(task, weight, data, tmp_path):
"""Test training resumes from an incomplete checkpoint."""
train_args = {
"data": data,
"epochs": 2,
"save": True,
"plots": False,
"workers": 0,
"project": tmp_path,
"name": task,
"imgsz": 32,
"exist_ok": True,
}
def stop_after_first_epoch(trainer):
if trainer.epoch == 0:
trainer.stop = True
def disable_final_eval(trainer):
trainer.final_eval = lambda: None
model = YOLO(weight)
model.add_callback("on_train_start", disable_final_eval)
model.add_callback("on_train_epoch_end", stop_after_first_epoch)
model.train(**train_args)
last_path = model.trainer.last
_, ckpt = load_checkpoint(last_path)
assert ckpt["epoch"] == 0, "checkpoint should be resumable"
# Resume training using the checkpoint
resume_model = YOLO(last_path)
resume_model.train(resume=True, **train_args)
assert resume_model.trainer.start_epoch == resume_model.trainer.epoch == 1, "resume test failed"
def test_nan_recovery():
"""Test NaN loss detection and recovery during training."""
nan_injected = [False]
def inject_nan(trainer):
"""Inject NaN into loss during batch processing to test recovery mechanism."""
if trainer.epoch == 1 and trainer.tloss is not None and not nan_injected[0]:
trainer.tloss *= torch.tensor(float("nan"))
nan_injected[0] = True
overrides = {"data": "coco8.yaml", "model": "yolo26n.yaml", "imgsz": 32, "epochs": 3}
trainer = detect.DetectionTrainer(overrides=overrides)
trainer.add_callback("on_train_batch_end", inject_nan)
trainer.train()
assert nan_injected[0], "NaN injection failed"
@pytest.mark.parametrize(
"kwargs,uses_weights",
[({}, True), ({"pretrained": True}, True), ({"pretrained": False}, False), ({"pretrained": MODEL}, True)],
)
def test_train_reuses_loaded_checkpoint_model(monkeypatch, kwargs, uses_weights):
"""Test training reuses loaded checkpoint config while respecting the pretrained argument."""
model = YOLO("yolo26n.yaml")
model.ckpt = {"checkpoint": True}
model.ckpt_path = "/tmp/fake.pt"
model.overrides["model"] = "ul://glenn-jocher/m2/exp-14"
model.overrides["pretrained"] = False
original_model = model.model
captured = {}
class FakeTrainer:
def __init__(self, overrides=None, _callbacks=None):
self.overrides = overrides
self.callbacks = _callbacks
self.model = None
self.validator = SimpleNamespace(metrics=None)
self.best = MODEL.parent / "nonexistent-best.pt"
self.last = MODEL
captured["trainer"] = self
def get_model(self, cfg=None, weights=None, verbose=True):
captured["cfg"] = cfg
captured["weights"] = weights
return original_model
def train(self):
return None
monkeypatch.setattr("ultralytics.engine.model.checks.check_pip_update_available", lambda: None)
monkeypatch.setattr(model, "_smart_load", lambda key: FakeTrainer)
monkeypatch.setattr(
"ultralytics.engine.model.load_checkpoint",
lambda path: (original_model, {"checkpoint": True}),
)
model.train(data="coco8.yaml", epochs=1, **kwargs)
assert captured["trainer"].model is original_model, "Trainer model does not match original"
assert captured["cfg"] == original_model.yaml, f"Config mismatch: {captured['cfg']} != {original_model.yaml}"
assert captured["weights"] is (original_model if uses_weights else None), "Unexpected weights loaded"
@pytest.mark.parametrize("pretrained,uses_weights", [(True, True), (False, False), (MODEL, True)])
def test_setup_model_respects_pretrained_arg_for_pt_models(monkeypatch, pretrained, uses_weights):
"""Test .pt models use checkpoint config while respecting the pretrained argument."""
captured = {}
checkpoint_model = SimpleNamespace(yaml={"nc": 80})
trainer = object.__new__(BaseTrainer)
trainer.model = "yolo26n.pt"
trainer.args = SimpleNamespace(pretrained=pretrained)
trainer.resume = False
def fake_get_model(cfg=None, weights=None, verbose=True):
captured["cfg"] = cfg
captured["weights"] = weights
return SimpleNamespace()
trainer.get_model = fake_get_model
monkeypatch.setattr(
"ultralytics.engine.trainer.load_checkpoint", lambda path: (checkpoint_model, {"checkpoint": True})
)
trainer.setup_model()
assert captured["cfg"] == checkpoint_model.yaml, "Checkpoint config was not used"
assert captured["weights"] is (checkpoint_model if uses_weights else None), "Unexpected weights loaded"