fix(image): patch realesrgan torchvision compatibility (#4110)

tests/test_realesrgan_torchvision_compat.py

@@ -0,0 +1,47 @@
+import sys
+import types
+
+from src.optional_deps import (
+    patch_realesrgan_torchvision_compat,
+    prepare_optional_dependency_import,
+)
+
+
+def test_realesrgan_patch_restores_removed_functional_tensor_module(monkeypatch):
+    for name in list(sys.modules):
+        if name.startswith("torchvision"):
+            monkeypatch.delitem(sys.modules, name, raising=False)
+
+    sentinel = object()
+    torchvision = types.ModuleType("torchvision")
+    transforms = types.ModuleType("torchvision.transforms")
+    functional = types.ModuleType("torchvision.transforms.functional")
+    functional.rgb_to_grayscale = sentinel
+    transforms.functional = functional
+    torchvision.transforms = transforms
+    monkeypatch.setitem(sys.modules, "torchvision", torchvision)
+    monkeypatch.setitem(sys.modules, "torchvision.transforms", transforms)
+    monkeypatch.setitem(sys.modules, "torchvision.transforms.functional", functional)
+
+    patch_realesrgan_torchvision_compat()
+
+    shim = sys.modules["torchvision.transforms.functional_tensor"]
+    assert shim.rgb_to_grayscale is sentinel
+    assert shim.rgb_to_grayscale is functional.rgb_to_grayscale
+
+
+def test_prepare_optional_dependency_import_scopes_patch_to_realesrgan(monkeypatch):
+    import src.optional_deps as optional_deps
+
+    calls = []
+    monkeypatch.setattr(
+        optional_deps,
+        "patch_realesrgan_torchvision_compat",
+        lambda: calls.append("patched"),
+    )
+
+    prepare_optional_dependency_import("diffusers")
+    assert calls == []
+
+    prepare_optional_dependency_import("realesrgan")
+    assert calls == ["patched"]