TST: adds test for Series and argwhere interaction (pandas-dev#53381)

* TST: adds test for Series and argwhere interaction

* Specify dtype for Win

* fix missing dtype

* fix linux 32bit int

Author: mcgeestocks

pandas/tests/series/test_npfuncs.py

@@ -3,8 +3,10 @@
 """
 
 import numpy as np
+import pytest
 
 from pandas import Series
+import pandas._testing as tm
 
 
 class TestPtp:
@@ -19,3 +21,15 @@ def test_ptp(self):
 def test_numpy_unique(datetime_series):
     # it works!
     np.unique(datetime_series)
+
+
+@pytest.mark.parametrize("index", [["a", "b", "c", "d", "e"], None])
+def test_numpy_argwhere(index):
+    # GH#35331
+
+    s = Series(range(5), index=index, dtype=np.int64)
+
+    result = np.argwhere(s > 2).astype(np.int64)
+    expected = np.array([[3], [4]], dtype=np.int64)
+
+    tm.assert_numpy_array_equal(result, expected)