add msg check for test_fill_null + remove unused import

Author: arw2019

python/pyarrow/tests/test_compute.py

@@ -736,7 +736,7 @@ def test_is_null():
 def test_fill_null():
     arr = pa.array([1, 2, None, 4], type=pa.int8())
     fill_value = pa.array([5], type=pa.int8())
-    with pytest.raises(pa.ArrowInvalid):
+    with pytest.raises(pa.ArrowInvalid, match="tried to convert to int"):
         arr.fill_null(fill_value)
 
     arr = pa.array([None, None, None, None], type=pa.null())

python/pyarrow/tests/test_pandas.py

@@ -19,7 +19,6 @@
 import decimal
 import json
 import multiprocessing as mp
-import re
 import sys
 
 from collections import OrderedDict