From 756c72438a6b9546cf2cf6b3ea023628ec81e8ff Mon Sep 17 00:00:00 2001
From: Deepak Cherian <deepak@cherian.net>
Date: Fri, 2 Aug 2024 15:53:04 -0600
Subject: [PATCH] Add more first, last tests

---
 tests/test_core.py | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/tests/test_core.py b/tests/test_core.py
index e12e695d..e9c5ebec 100644
--- a/tests/test_core.py
+++ b/tests/test_core.py
@@ -613,6 +613,33 @@ def test_dask_reduce_axis_subset():
         )
 
 
+@pytest.mark.parametrize(
+    "func",
+    [
+        # "first", "last",
+        "nanfirst",
+        "nanlast",
+    ],
+)
+@pytest.mark.parametrize(
+    "chunks",
+    [
+        None,
+        pytest.param(1, marks=pytest.mark.skipif(not has_dask, reason="no dask")),
+        pytest.param(2, marks=pytest.mark.skipif(not has_dask, reason="no dask")),
+        pytest.param(3, marks=pytest.mark.skipif(not has_dask, reason="no dask")),
+    ],
+)
+def test_first_last_useless(func, chunks):
+    array = np.array([[0, 0, 0], [0, 0, 0]], dtype=np.int8)
+    group_idx = np.array([1, 0, 0])
+    if chunks is not None:
+        array = dask.array.from_array(array, chunks=chunks)
+    actual, _ = groupby_reduce(array, group_idx, func=func, engine="numpy")
+    expected = np.array([[0, 0], [0, 0]], dtype=np.int8)
+    assert_equal(actual, expected)
+
+
 @pytest.mark.parametrize("func", ["first", "last", "nanfirst", "nanlast"])
 @pytest.mark.parametrize("axis", [(0, 1)])
 def test_first_last_disallowed(axis, func):