Fix nonzero of a SparseArray

pandas/tests/sparse/frame/test_frame.py

@@ -1350,3 +1350,11 @@ def test_assign_with_sparse_frame(self):
 
         for column in res.columns:
             assert type(res[column]) is SparseSeries
+
+    def test_dropna(self):
+        tm.assert_sp_frame_equal(
+            pd.SparseDataFrame({"F2": [0, 1]}),
+            pd.SparseDataFrame(
+                {"F1": [float('nan'), float('nan')], "F2": [0, 1]}
+            ).dropna(axis=1, inplace=False, how='all')
+        )

pandas/tests/sparse/test_indexing.py

@@ -455,6 +455,25 @@ def tests_indexing_with_sparse(self, kind, fill):
             s.iloc[indexer]
 
 
+class TestSparseArray(object):
+
+    def test_nonzero(self):
+        sa = pd.SparseArray([
+            float('nan'),
+            float('nan'),
+            1, 0, 0,
+            2, 0, 0, 0,
+            3, 0, 0
+        ])
+        tm.assert_numpy_array_equal(np.array([2, 5, 9], dtype=np.int32),
+                                    sa.nonzero()[0])
+
+        sa = pd.SparseArray(
+            [0, 0, 1, 0, 0, 2, 0, 0, 0, 3, 0, 0])
+        tm.assert_numpy_array_equal(np.array([2, 5, 9], dtype=np.int32),
+                                    sa.nonzero()[0])
+
+
 class TestSparseSeriesMultiIndexing(TestSparseSeriesIndexing):
 
     def setup_method(self, method):