GH-51229: [Python] Raise instead of crashing on unopened resize

python/pyarrow/io.pxi

@@ -1101,6 +1101,7 @@ cdef class MemoryMappedFile(NativeFile):
         ----------
         new_size : new size in bytes
         """
+        self._assert_open()
         check_status(self.handle.get().Resize(new_size))
 
     def fileno(self):

python/pyarrow/tests/test_io.py

@@ -27,6 +27,7 @@
 import pathlib
 import pytest
 import random
+import subprocess
 import sys
 import tempfile
 import weakref
@@ -1216,6 +1217,24 @@ def test_memory_map_resize(tmpdir):
         assert f.read() == bytes(arr[:SIZE])
 
 
+def test_memory_map_resize_uninitialized():
+    code = """if 1:
+    import pyarrow as pa
+
+    try:
+        pa.MemoryMappedFile().resize(0)
+    except ValueError as exc:
+        assert str(exc) == "I/O operation on closed file"
+    else:
+        raise AssertionError("expected ValueError")
+    """
+    res = subprocess.run([sys.executable, "-c", code],
+                         universal_newlines=True, stderr=subprocess.PIPE)
+    if res.returncode != 0:
+        print(res.stderr, file=sys.stderr)
+        res.check_returncode()
+
+
 def test_memory_zero_length(tmpdir):
     path = os.path.join(str(tmpdir), guid())
     f = open(path, 'wb')