split node tests into standalone files

tests/node_tests/test_image_demo.py

@@ -0,0 +1,70 @@
+import os
+from unittest.mock import patch
+
+import numpy as np
+from backend.data_types import DataField
+from backend.execution import ExecutionEngine
+import backend.nodes  # noqa: F401
+
+
+def test_load_demo():
+    from backend.nodes.image_demo import ImageDemo
+    node = ImageDemo()
+
+    result = node.load(name="nanoparticles.npy")
+    assert len(result) >= 1
+    assert isinstance(result[0], DataField)
+    assert result[0].data.ndim == 2
+
+    result_ibw = node.load(name="whiskers.ibw")
+    assert len(result_ibw) == 4
+    for field in result_ibw:
+        assert isinstance(field, DataField)
+
+    try:
+        node.load(name="nonexistent_file.png")
+        assert False, "Should have raised FileNotFoundError"
+    except FileNotFoundError:
+        pass
+
+
+def test_load_demo_cache():
+    from backend.nodes.image import Image
+    from backend.nodes.image_demo import ImageDemo
+
+    node = ImageDemo()
+    Image._load_fields_cached.cache_clear()
+
+    with patch.object(Image, "_load_image_or_array", wraps=Image._load_image_or_array) as loader:
+        first, = node.load(name="nanoparticles.npy")
+        second, = node.load(name="nanoparticles.npy")
+        assert loader.call_count == 1
+
+    assert np.allclose(first.data, second.data)
+    assert first is not second
+    first.data[0, 0] = -999.0
+
+    third, = node.load(name="nanoparticles.npy")
+    assert third.data[0, 0] != -999.0
+
+    Image._load_fields_cached.cache_clear()
+
+
+def test_load_demo_multi_layer_preview_payload():
+    previews = []
+    prompt = {
+        "1": {
+            "class_type": "ImageDemo",
+            "inputs": {"name": "whiskers.ibw", "colormap": "viridis"},
+        },
+    }
+
+    ExecutionEngine().execute(prompt, on_preview=lambda node_id, payload: previews.append((node_id, payload)))
+
+    assert len(previews) == 1
+    node_id, payload = previews[0]
+    assert node_id == "1"
+    assert payload["kind"] == "layer_gallery"
+    assert len(payload["layers"]) == 4
+    assert all(isinstance(layer["name"], str) and layer["name"] for layer in payload["layers"])
+    assert all(layer["image"].startswith("data:image/png;base64,") for layer in payload["layers"])