Add failing test for #5065.

tests/forward_reference_type.py

@@ -0,0 +1,9 @@
+from pydantic import BaseModel
+
+
+def forwardref_method(input: "ForwardRef") -> "ForwardRef":
+    return ForwardRef()
+
+
+class ForwardRef(BaseModel):
+    x: int = 0

tests/test_wrapped_method_forward_reference.py

@@ -0,0 +1,24 @@
+import functools
+
+from fastapi import FastAPI
+
+from .forward_reference_type import forwardref_method
+
+
+def passthrough(f):
+    @functools.wraps(f)
+    def method(*args, **kwargs):
+        return f(*args, **kwargs)
+
+    return method
+
+
+def test_wrapped_method_type_inference():
+    """
+    Regression test ensuring that when a method imported from another module
+    is decorated with something that sets the __wrapped__ attribute, then
+    the types are still processed correctly, including dereferencing of forward
+    references.
+    """
+    app = FastAPI()
+    app.get("/endpoint")(passthrough(forwardref_method))