test: add @ioana's tests of to_arraylib. (#1908)

* test: add @ioana's tests of to_arraylib.

* Fix the formatting (black).

tests/test_1765-add-ioanas-test-of-to_arraylib.py

@@ -0,0 +1,33 @@
+# BSD 3-Clause License; see https://github.com/scikit-hep/awkward-1.0/blob/main/LICENSE
+
+import numpy as np  # noqa: F401
+import pytest  # noqa: F401
+
+import awkward as ak  # noqa: F401
+
+
+def test():
+    aa = ak.contents.NumpyArray(
+        np.frombuffer(b"hellothere", "u1"), parameters={"__array__": "bytestring"}
+    )
+    b = ak._util.to_arraylib(np, aa, False)
+    assert b.tolist() == [104, 101, 108, 108, 111, 116, 104, 101, 114, 101]
+    assert b.dtype == np.dtype(np.uint8)
+
+    c = ak.contents.NumpyArray(np.array([0, 1577836800], dtype="datetime64[s]"))
+    assert [d.isoformat() for d in ak._util.to_arraylib(np, c, False).tolist()] == [
+        "1970-01-01T00:00:00",
+        "2020-01-01T00:00:00",
+    ]
+
+    recordarray = ak.contents.RecordArray(
+        [ak.contents.NumpyArray(np.array([1, 2, 3, 4, 5], dtype=np.int64))],
+        fields=["one"],
+    )
+    assert ak._util.to_arraylib(np, recordarray, False).tolist() == [
+        (1,),
+        (2,),
+        (3,),
+        (4,),
+        (5,),
+    ]