Test model device manager and fix bugs

tests/inference/test_modelmanager.py

@@ -0,0 +1,51 @@
+import numpy
+from PIL import Image
+import pytest
+from pytest import fixture
+import torch
+from typing import Tuple, Optional
+
+from sgm.inference.api import (
+    model_specs,
+    SamplingParams,
+    SamplingPipeline,
+    Sampler,
+    ModelArchitecture,    
+)
+import sgm.inference.helpers as helpers
+
+def get_torch_device(model: torch.nn.Module) -> torch.device:
+    param = next(model.parameters(), None)
+    if param is not None:
+        return param.device
+    else:
+        buf = next(model.buffers(), None)
+        if buf is not None:
+            return buf.device
+        else:                
+            raise TypeError("Could not determine device of input model")
+    
+
+@pytest.mark.inference
+def test_default_loading():
+    pipeline = SamplingPipeline(model_id=ModelArchitecture.SD_2_1)
+    assert get_torch_device(pipeline.model.model).type == "cuda"
+    assert get_torch_device(pipeline.model.conditioner).type == "cuda"
+    with pipeline.device_manager.use(pipeline.model.model):
+        assert get_torch_device(pipeline.model.model).type == "cuda"
+    assert get_torch_device(pipeline.model.model).type == "cuda"
+    with pipeline.device_manager.use(pipeline.model.conditioner):
+        assert get_torch_device(pipeline.model.conditioner).type == "cuda"
+    assert get_torch_device(pipeline.model.conditioner).type == "cuda"
+
+@pytest.mark.inference
+def test_model_swapping():
+    pipeline = SamplingPipeline(model_id=ModelArchitecture.SD_2_1, device=helpers.CudaModelManager(device="cuda", swap_device="cpu"))
+    assert get_torch_device(pipeline.model.model).type == "cpu"
+    assert get_torch_device(pipeline.model.conditioner).type == "cpu"
+    with pipeline.device_manager.use(pipeline.model.model):
+        assert get_torch_device(pipeline.model.model).type == "cuda"
+    assert get_torch_device(pipeline.model.model).type == "cpu"
+    with pipeline.device_manager.use(pipeline.model.conditioner):
+        assert get_torch_device(pipeline.model.conditioner).type == "cuda"
+    assert get_torch_device(pipeline.model.conditioner).type == "cpu"