Revert "remove new tests for debug"

This reverts commit 29d6849.

Author: AlexKirko

pandas/conftest.py

@@ -437,6 +437,28 @@ def index(request):
 index_fixture2 = index
 
 
+@pytest.fixture(params=indices_dict.keys())
+def index_with_missing(request):
+    """
+    Fixture for indices with missing values
+    """
+    if request.param in ["int", "uint", "range", "empty", "repeats"]:
+        pytest.xfail("missing values not supported")
+    ind = indices_dict[request.param].copy()
+    vals = ind.values
+    if type(vals[0]) == tuple:
+        # For setting missing values in the top level of MultiIndex
+        vals = ind.tolist()
+        vals[0] = tuple([None]) + vals[0][1:]
+        vals[-1] = tuple([None]) + vals[-1][1:]
+        ind = MultiIndex.from_tuples(vals)
+    else:
+        vals[0] = None
+        vals[-1] = None
+        ind = type(ind)(vals)
+    return ind
+
+
 # ----------------------------------------------------------------
 # Series'
 # ----------------------------------------------------------------

pandas/tests/indexes/test_common.py

@@ -398,3 +398,40 @@ def test_astype_preserves_name(self, index, dtype):
             assert result.names == index.names
         else:
             assert result.name == index.name
+
+
+@pytest.mark.parametrize("na_position", [None, "middle"])
+def test_sort_values_invalid_na_position(index_with_missing, na_position):
+
+    if type(index_with_missing) in [DatetimeIndex, PeriodIndex, TimedeltaIndex]:
+        pytest.xfail("stable descending order sort not implemented")
+    elif type(index_with_missing) in [CategoricalIndex, MultiIndex]:
+        pytest.xfail("missing value sorting order not defined for index type")
+
+    if na_position not in ["first", "last"]:
+        with pytest.raises(
+            ValueError, match=f"invalid na_position: {na_position}",
+        ):
+            index_with_missing.sort_values(na_position=na_position)
+
+
+@pytest.mark.parametrize("na_position", ["first", "last"])
+def test_sort_values_with_missing(index_with_missing, na_position):
+    # GH 35584. Test that sort_values works with missing values,
+    # sort non-missing and place missing according to na_position
+
+    if type(index_with_missing) in [DatetimeIndex, PeriodIndex, TimedeltaIndex]:
+        pytest.xfail("stable descending order sort not implemented")
+    elif type(index_with_missing) in [CategoricalIndex, MultiIndex]:
+        pytest.xfail("missing value sorting order not defined for index type")
+    missing_count = np.sum(index_with_missing.isna())
+    not_na_vals = index_with_missing[index_with_missing.notna()].values
+    sorted_values = np.sort(not_na_vals)
+    if na_position == "first":
+        sorted_values = np.concatenate([[None] * missing_count, sorted_values])
+    else:
+        sorted_values = np.concatenate([sorted_values, [None] * missing_count])
+    expected = type(index_with_missing)(sorted_values)
+
+    result = index_with_missing.sort_values(na_position=na_position)
+    tm.assert_index_equal(result, expected)