test(model_management): add a couple tests for _get_model_path

tests/test_model_manager.py

@@ -0,0 +1,36 @@
+from pathlib import Path
+
+import pytest
+
+from invokeai.app.services.config import InvokeAIAppConfig
+from invokeai.backend import ModelManager, BaseModelType, ModelType, SubModelType
+
+
+@pytest.fixture
+def model_manager(datadir) -> ModelManager:
+    InvokeAIAppConfig.get_config(root=datadir)
+    return ModelManager(datadir / "configs" / "relative_sub.models.yaml")
+
+
+def test_get_model_names(model_manager: ModelManager):
+    names = model_manager.model_names()
+    assert names[:2] == [
+        ("SDXL base", BaseModelType.StableDiffusionXL, ModelType.Main),
+        ("SDXL with VAE", BaseModelType.StableDiffusionXL, ModelType.Main),
+    ]
+
+
+def test_get_model_path_for_diffusers(model_manager: ModelManager, datadir: Path):
+    model_config = model_manager._get_model_config(BaseModelType.StableDiffusionXL, "SDXL base", ModelType.Main)
+    top_model_path, is_override = model_manager._get_model_path(model_config)
+    expected_model_path = datadir / "models" / "sdxl" / "main" / "SDXL base 1_0"
+    assert top_model_path == expected_model_path
+    assert not is_override
+
+
+def test_get_model_path_for_overridden_vae(model_manager: ModelManager, datadir: Path):
+    model_config = model_manager._get_model_config(BaseModelType.StableDiffusionXL, "SDXL with VAE", ModelType.Main)
+    vae_model_path, is_override = model_manager._get_model_path(model_config, SubModelType.Vae)
+    expected_vae_path = datadir / "models" / "sdxl" / "vae" / "sdxl-vae-fp16-fix"
+    assert vae_model_path == expected_vae_path
+    assert is_override

tests/test_model_manager/configs/relative_sub.models.yaml

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+__metadata__:
+  version: 3.0.0
+
+sdxl/main/SDXL base:
+  path: sdxl/main/SDXL base 1_0
+  description: SDXL base v1.0
+  variant: normal
+  format: diffusers
+
+sdxl/main/SDXL with VAE:
+  path: sdxl/main/SDXL base 1_0
+  description: SDXL base v1.0
+  vae: sdxl/vae/sdxl-vae-fp16-fix/
+  variant: normal
+  format: diffusers