From e96054a5315c0924bb241d53a72580ec8faeb9b5 Mon Sep 17 00:00:00 2001
From: cmmck <70769004+ConnorMcKinley@users.noreply.github.com>
Date: Wed, 19 Apr 2023 18:13:11 -0400
Subject: [PATCH] TST: Add regression test for NaN sparse columns (#52772)

* Add test for GH 27781

* Modify test for GH 27781
---
 pandas/tests/arrays/sparse/test_array.py | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/pandas/tests/arrays/sparse/test_array.py b/pandas/tests/arrays/sparse/test_array.py
index 54c8e359b2859..4a0795137f80b 100644
--- a/pandas/tests/arrays/sparse/test_array.py
+++ b/pandas/tests/arrays/sparse/test_array.py
@@ -478,3 +478,15 @@ def test_drop_duplicates_fill_value():
     result = df.drop_duplicates()
     expected = pd.DataFrame({i: SparseArray([0.0], fill_value=0) for i in range(5)})
     tm.assert_frame_equal(result, expected)
+
+
+def test_zero_sparse_column():
+    # GH 27781
+    df1 = pd.DataFrame({"A": SparseArray([0, 0, 0]), "B": [1, 2, 3]})
+    df2 = pd.DataFrame({"A": SparseArray([0, 1, 0]), "B": [1, 2, 3]})
+    result = df1.loc[df1["B"] != 2]
+    expected = df2.loc[df2["B"] != 2]
+    tm.assert_frame_equal(result, expected)
+
+    expected = pd.DataFrame({"A": SparseArray([0, 0]), "B": [1, 3]}, index=[0, 2])
+    tm.assert_frame_equal(result, expected)