Reject non-callable ext_hook consistently in C extension

msgpack/_unpacker.pyx

@@ -71,7 +71,7 @@ cdef inline init_ctx(unpack_context *ctx,
     ctx.user.use_list = use_list
     ctx.user.raw = raw
     ctx.user.strict_map_key = strict_map_key
-    ctx.user.object_hook = ctx.user.list_hook = <PyObject*>NULL
+    ctx.user.object_hook = ctx.user.list_hook = ctx.user.ext_hook = <PyObject*>NULL
     ctx.user.max_str_len = max_str_len
     ctx.user.max_bin_len = max_bin_len
     ctx.user.max_array_len = max_array_len
@@ -99,10 +99,9 @@ cdef inline init_ctx(unpack_context *ctx,
             raise TypeError("list_hook must be a callable.")
         ctx.user.list_hook = <PyObject*>list_hook
 
-    if ext_hook is not None:
-        if not PyCallable_Check(ext_hook):
-            raise TypeError("ext_hook must be a callable.")
-        ctx.user.ext_hook = <PyObject*>ext_hook
+    if not PyCallable_Check(ext_hook):
+        raise TypeError("ext_hook must be a callable.")
+    ctx.user.ext_hook = <PyObject*>ext_hook
 
     if timestamp < 0 or 3 < timestamp:
         raise ValueError("timestamp must be 0..3")

test/test_extension.py

@@ -1,9 +1,37 @@
 import array
 
+import pytest
+
 import msgpack
 from msgpack import ExtType
 
 
+@pytest.mark.parametrize("ext_hook", [None, 0, "hook", []])
+def test_unpackb_invalid_ext_hook(ext_hook):
+    with pytest.raises(TypeError, match="ext_hook.*callable"):
+        msgpack.unpackb(b"\xc0", ext_hook=ext_hook)
+
+
+@pytest.mark.parametrize("ext_hook", [None, 0, "hook", []])
+def test_unpacker_invalid_ext_hook(ext_hook):
+    with pytest.raises(TypeError, match="ext_hook.*callable"):
+        msgpack.Unpacker(ext_hook=ext_hook)
+
+
+@pytest.mark.parametrize("ext_hook", [None, 0, "hook", []])
+def test_unpacker_reinit_invalid_ext_hook(ext_hook):
+    unpacker = msgpack.Unpacker(ext_hook=lambda code, data: (code, data))
+    unpacker.feed(b"\xd4\x42A")
+    assert unpacker.unpack() == (0x42, b"A")
+
+    with pytest.raises(TypeError, match="ext_hook.*callable"):
+        unpacker.__init__(ext_hook=ext_hook)
+
+    unpacker.__init__()
+    unpacker.feed(b"\xd4\x42A")
+    assert unpacker.unpack() == ExtType(0x42, b"A")
+
+
 def test_pack_ext_type():
     def p(s):
         packer = msgpack.Packer(autoreset=False)