(add) test.source for unittest

+commit b5a5268dabb2a4dea1c3c543a1ddff501b87a447
+Author: jbrockmendel <jbrockmendel@gmail.com>
+Date:   Tue Sep 8 18:33:41 2020 -0700
+
+    STY: De-privatize imported names (#36235)
+
+diff --git a/pandas/_libs/interval.pyx b/pandas/_libs/interval.pyx
+index 931ad8326..f8bcbcfb1 100644
+--- a/pandas/_libs/interval.pyx
++++ b/pandas/_libs/interval.pyx
+@@ -46,7 +46,7 @@ from pandas._libs.tslibs.util cimport (
+     is_timedelta64_object,
+ )
+
+-_VALID_CLOSED = frozenset(['left', 'right', 'both', 'neither'])
++VALID_CLOSED = frozenset(['left', 'right', 'both', 'neither'])
+
+
+ cdef class IntervalMixin:
+@@ -318,7 +318,7 @@ cdef class Interval(IntervalMixin):
+         self._validate_endpoint(left)
+         self._validate_endpoint(right)
+
+-        if closed not in _VALID_CLOSED:
++        if closed not in VALID_CLOSED:
+             raise ValueError(f"invalid option for 'closed': {closed}")
+         if not left <= right:
+             raise ValueError("left side of interval must be <= right side")
+diff --git a/pandas/core/arrays/_arrow_utils.py b/pandas/core/arrays/_arrow_utils.py
+index 4a33e0e84..c89f5554d 100644
+--- a/pandas/core/arrays/_arrow_utils.py
++++ b/pandas/core/arrays/_arrow_utils.py
+@@ -4,7 +4,7 @@ import json
+ import numpy as np
+ import pyarrow
+
+-from pandas.core.arrays.interval import _VALID_CLOSED
++from pandas.core.arrays.interval import VALID_CLOSED
+
+ _pyarrow_version_ge_015 = LooseVersion(pyarrow.__version__) >= LooseVersion("0.15")
+
+@@ -83,7 +83,7 @@ if _pyarrow_version_ge_015:
+         def __init__(self, subtype, closed):
+             # attributes need to be set first before calling
+             # super init (as that calls serialize)
+-            assert closed in _VALID_CLOSED
++            assert closed in VALID_CLOSED
+             self._closed = closed
+             if not isinstance(subtype, pyarrow.DataType):
+                 subtype = pyarrow.type_for_alias(str(subtype))
+diff --git a/pandas/core/arrays/interval.py b/pandas/core/arrays/interval.py
+index d76e0fd62..1dbd3cfc6 100644
+--- a/pandas/core/arrays/interval.py
++++ b/pandas/core/arrays/interval.py
+@@ -5,7 +5,12 @@ import numpy as np
+
+ from pandas._config import get_option
+
+-from pandas._libs.interval import Interval, IntervalMixin, intervals_to_interval_bounds
++from pandas._libs.interval import (
++    VALID_CLOSED,
++    Interval,
++    IntervalMixin,
++    intervals_to_interval_bounds,
++)
+ from pandas.compat.numpy import function as nv
+ from pandas.util._decorators import Appender
+
+@@ -42,7 +47,6 @@ from pandas.core.construction import array
+ from pandas.core.indexers import check_array_indexer
+ from pandas.core.indexes.base import ensure_index
+
+-_VALID_CLOSED = {"left", "right", "both", "neither"}
+ _interval_shared_docs = {}
+
+ _shared_docs_kwargs = dict(
+@@ -475,7 +479,7 @@ class IntervalArray(IntervalMixin, ExtensionArray):
+         * left and right have the same missing values
+         * left is always below right
+         """
+-        if self.closed not in _VALID_CLOSED:
++        if self.closed not in VALID_CLOSED:
+             msg = f"invalid option for 'closed': {self.closed}"
+             raise ValueError(msg)
+         if len(self.left) != len(self.right):
+@@ -1012,7 +1016,7 @@ class IntervalArray(IntervalMixin, ExtensionArray):
+         )
+     )
+     def set_closed(self, closed):
+-        if closed not in _VALID_CLOSED:
++        if closed not in VALID_CLOSED:
+             msg = f"invalid option for 'closed': {closed}"
+             raise ValueError(msg)
+
+diff --git a/pandas/core/arrays/sparse/__init__.py b/pandas/core/arrays/sparse/__init__.py
+index e928db499..e9ff4b7d4 100644
+--- a/pandas/core/arrays/sparse/__init__.py
++++ b/pandas/core/arrays/sparse/__init__.py
+@@ -5,6 +5,6 @@ from pandas.core.arrays.sparse.array import (
+     BlockIndex,
+     IntIndex,
+     SparseArray,
+-    _make_index,
++    make_sparse_index,
+ )
+ from pandas.core.arrays.sparse.dtype import SparseDtype
+diff --git a/pandas/core/arrays/sparse/array.py b/pandas/core/arrays/sparse/array.py
+index 47c960dc9..853f7bb0b 100644
+--- a/pandas/core/arrays/sparse/array.py
++++ b/pandas/core/arrays/sparse/array.py
+@@ -1556,7 +1556,7 @@ def make_sparse(arr: np.ndarray, kind="block", fill_value=None, dtype=None, copy
+     else:
+         indices = mask.nonzero()[0].astype(np.int32)
+
+-    index = _make_index(length, indices, kind)
++    index = make_sparse_index(length, indices, kind)
+     sparsified_values = arr[mask]
+     if dtype is not None:
+         sparsified_values = astype_nansafe(sparsified_values, dtype=dtype)
+@@ -1564,7 +1564,7 @@ def make_sparse(arr: np.ndarray, kind="block", fill_value=None, dtype=None, copy
+     return sparsified_values, index, fill_value
+
+
+-def _make_index(length, indices, kind):
++def make_sparse_index(length, indices, kind):
+
+     if kind == "block" or isinstance(kind, BlockIndex):
+         locs, lens = splib.get_blocks(indices)
+diff --git a/pandas/core/computation/engines.py b/pandas/core/computation/engines.py
+index 0cdc0f530..77a378369 100644
+--- a/pandas/core/computation/engines.py
++++ b/pandas/core/computation/engines.py
+@@ -130,7 +130,7 @@ class PythonEngine(AbstractEngine):
+         pass
+
+
+-_engines: Dict[str, Type[AbstractEngine]] = {
++ENGINES: Dict[str, Type[AbstractEngine]] = {
+     "numexpr": NumExprEngine,
+     "python": PythonEngine,
+ }
+diff --git a/pandas/core/computation/eval.py b/pandas/core/computation/eval.py
+index f6a793514..630606b4d 100644
+--- a/pandas/core/computation/eval.py
++++ b/pandas/core/computation/eval.py
+@@ -9,8 +9,8 @@ import warnings
+ from pandas._libs.lib import no_default
+ from pandas.util._validators import validate_bool_kwarg
+
+-from pandas.core.computation.engines import _engines
+-from pandas.core.computation.expr import Expr, _parsers
++from pandas.core.computation.engines import ENGINES
++from pandas.core.computation.expr import PARSERS, Expr
+ from pandas.core.computation.parsing import tokenize_string
+ from pandas.core.computation.scope import ensure_scope
+
+@@ -43,8 +43,8 @@ def _check_engine(engine: Optional[str]) -> str:
+     if engine is None:
+         engine = "numexpr" if NUMEXPR_INSTALLED else "python"
+
+-    if engine not in _engines:
+-        valid_engines = list(_engines.keys())
++    if engine not in ENGINES:
++        valid_engines = list(ENGINES.keys())
+         raise KeyError(
+             f"Invalid engine '{engine}' passed, valid engines are {valid_engines}"
+         )
+@@ -75,9 +75,9 @@ def _check_parser(parser: str):
+     KeyError
+       * If an invalid parser is passed
+     """
+-    if parser not in _parsers:
++    if parser not in PARSERS:
+         raise KeyError(
+-            f"Invalid parser '{parser}' passed, valid parsers are {_parsers.keys()}"
++            f"Invalid parser '{parser}' passed, valid parsers are {PARSERS.keys()}"
+         )
+
+
+@@ -341,7 +341,7 @@ def eval(
+         parsed_expr = Expr(expr, engine=engine, parser=parser, env=env)
+
+         # construct the engine and evaluate the parsed expression
+-        eng = _engines[engine]
++        eng = ENGINES[engine]
+         eng_inst = eng(parsed_expr)
+         ret = eng_inst.evaluate()
+
+diff --git a/pandas/core/computation/expr.py b/pandas/core/computation/expr.py
+index 8cff6abc0..f5897277d 100644
+--- a/pandas/core/computation/expr.py
++++ b/pandas/core/computation/expr.py
+@@ -782,7 +782,7 @@ class Expr:
+         self.env = env or Scope(level=level + 1)
+         self.engine = engine
+         self.parser = parser
+-        self._visitor = _parsers[parser](self.env, self.engine, self.parser)
++        self._visitor = PARSERS[parser](self.env, self.engine, self.parser)
+         self.terms = self.parse()
+
+     @property
+@@ -814,4 +814,4 @@ class Expr:
+         return frozenset(term.name for term in com.flatten(self.terms))
+
+
+-_parsers = {"python": PythonExprVisitor, "pandas": PandasExprVisitor}
++PARSERS = {"python": PythonExprVisitor, "pandas": PandasExprVisitor}
+diff --git a/pandas/core/config_init.py b/pandas/core/config_init.py
+index 0c23f1b4b..bfe20551c 100644
+--- a/pandas/core/config_init.py
++++ b/pandas/core/config_init.py
+@@ -314,9 +314,9 @@ pc_latex_multirow = """
+
+
+ def table_schema_cb(key):
+-    from pandas.io.formats.printing import _enable_data_resource_formatter
++    from pandas.io.formats.printing import enable_data_resource_formatter
+
+-    _enable_data_resource_formatter(cf.get_option(key))
++    enable_data_resource_formatter(cf.get_option(key))
+
+
+ def is_terminal() -> bool:
+diff --git a/pandas/core/groupby/generic.py b/pandas/core/groupby/generic.py
+index 72003eab2..e870187fc 100644
+--- a/pandas/core/groupby/generic.py
++++ b/pandas/core/groupby/generic.py
+@@ -70,9 +70,9 @@ from pandas.core.groupby.groupby import (
+     GroupBy,
+     _agg_template,
+     _apply_docs,
+-    _group_selection_context,
+     _transform_template,
+     get_groupby,
++    group_selection_context,
+ )
+ from pandas.core.groupby.numba_ import generate_numba_func, split_for_numba
+ from pandas.core.indexes.api import Index, MultiIndex, all_indexes_same
+@@ -230,7 +230,7 @@ class SeriesGroupBy(GroupBy[Series]):
+                 raise NotImplementedError(
+                     "Numba engine can only be used with a single function."
+                 )
+-            with _group_selection_context(self):
++            with group_selection_context(self):
+                 data = self._selected_obj
+             result, index = self._aggregate_with_numba(
+                 data.to_frame(), func, *args, engine_kwargs=engine_kwargs, **kwargs
+@@ -685,7 +685,7 @@ class SeriesGroupBy(GroupBy[Series]):
+         self, normalize=False, sort=True, ascending=False, bins=None, dropna=True
+     ):
+
+-        from pandas.core.reshape.merge import _get_join_indexers
++        from pandas.core.reshape.merge import get_join_indexers
+         from pandas.core.reshape.tile import cut
+
+         if bins is not None and not np.iterable(bins):
+@@ -787,7 +787,7 @@ class SeriesGroupBy(GroupBy[Series]):
+
+         right = [diff.cumsum() - 1, codes[-1]]
+
+-        _, idx = _get_join_indexers(left, right, sort=False, how="left")
++        _, idx = get_join_indexers(left, right, sort=False, how="left")
+         out = np.where(idx != -1, out[idx], 0)
+
+         if sort:
+@@ -942,7 +942,7 @@ class DataFrameGroupBy(GroupBy[DataFrame]):
+                 raise NotImplementedError(
+                     "Numba engine can only be used with a single function."
+                 )
+-            with _group_selection_context(self):
++            with group_selection_context(self):
+                 data = self._selected_obj
+             result, index = self._aggregate_with_numba(
+                 data, func, *args, engine_kwargs=engine_kwargs, **kwargs
+diff --git a/pandas/core/groupby/groupby.py b/pandas/core/groupby/groupby.py
+index 6ef2e6703..1e3e56f4f 100644
+--- a/pandas/core/groupby/groupby.py
++++ b/pandas/core/groupby/groupby.py
+@@ -459,9 +459,9 @@ class GroupByPlot(PandasObject):
+
+
+ @contextmanager
+-def _group_selection_context(groupby: "_GroupBy"):
++def group_selection_context(groupby: "_GroupBy"):
+     """
+-    Set / reset the _group_selection_context.
++    Set / reset the group_selection_context.
+     """
+     groupby._set_group_selection()
+     try:
+@@ -737,7 +737,7 @@ b  2""",
+     def _make_wrapper(self, name: str) -> Callable:
+         assert name in self._apply_allowlist
+
+-        with _group_selection_context(self):
++        with group_selection_context(self):
+             # need to setup the selection
+             # as are not passed directly but in the grouper
+             f = getattr(self._obj_with_exclusions, name)
+@@ -868,7 +868,7 @@ b  2""",
+                 # fails on *some* columns, e.g. a numeric operation
+                 # on a string grouper column
+
+-                with _group_selection_context(self):
++                with group_selection_context(self):
+                     return self._python_apply_general(f, self._selected_obj)
+
+         return result
+@@ -994,7 +994,7 @@ b  2""",
+         alias: str,
+         npfunc: Callable,
+     ):
+-        with _group_selection_context(self):
++        with group_selection_context(self):
+             # try a cython aggregation if we can
+             try:
+                 return self._cython_agg_general(
+@@ -1499,7 +1499,7 @@ class GroupBy(_GroupBy[FrameOrSeries]):
+             )
+         else:
+             func = lambda x: x.var(ddof=ddof)
+-            with _group_selection_context(self):
++            with group_selection_context(self):
+                 return self._python_agg_general(func)
+
+     @Substitution(name="groupby")
+@@ -1658,7 +1658,7 @@ class GroupBy(_GroupBy[FrameOrSeries]):
+
+     @doc(DataFrame.describe)
+     def describe(self, **kwargs):
+-        with _group_selection_context(self):
++        with group_selection_context(self):
+             result = self.apply(lambda x: x.describe(**kwargs))
+             if self.axis == 1:
+                 return result.T
+@@ -1963,7 +1963,7 @@ class GroupBy(_GroupBy[FrameOrSeries]):
+                 nth_values = list(set(n))
+
+             nth_array = np.array(nth_values, dtype=np.intp)
+-            with _group_selection_context(self):
++            with group_selection_context(self):
+
+                 mask_left = np.in1d(self._cumcount_array(), nth_array)
+                 mask_right = np.in1d(
+@@ -2226,7 +2226,7 @@ class GroupBy(_GroupBy[FrameOrSeries]):
+         5    0
+         dtype: int64
+         """
+-        with _group_selection_context(self):
++        with group_selection_context(self):
+             index = self._selected_obj.index
+             result = self._obj_1d_constructor(self.grouper.group_info[0], index)
+             if not ascending:
+@@ -2287,7 +2287,7 @@ class GroupBy(_GroupBy[FrameOrSeries]):
+         5    0
+         dtype: int64
+         """
+-        with _group_selection_context(self):
++        with group_selection_context(self):
+             index = self._selected_obj.index
+             cumcounts = self._cumcount_array(ascending=ascending)
+             return self._obj_1d_constructor(cumcounts, index)
+diff --git a/pandas/core/indexes/base.py b/pandas/core/indexes/base.py
+index 526dae7e2..8014b16d0 100644
+--- a/pandas/core/indexes/base.py
++++ b/pandas/core/indexes/base.py
+@@ -3660,7 +3660,7 @@ class Index(IndexOpsMixin, PandasObject):
+         return result
+
+     def _join_non_unique(self, other, how="left", return_indexers=False):
+-        from pandas.core.reshape.merge import _get_join_indexers
++        from pandas.core.reshape.merge import get_join_indexers
+
+         # We only get here if dtypes match
+         assert self.dtype == other.dtype
+@@ -3668,7 +3668,7 @@ class Index(IndexOpsMixin, PandasObject):
+         lvalues = self._get_engine_target()
+         rvalues = other._get_engine_target()
+
+-        left_idx, right_idx = _get_join_indexers(
++        left_idx, right_idx = get_join_indexers(
+             [lvalues], [rvalues], how=how, sort=True
+         )
+
+diff --git a/pandas/core/indexes/interval.py b/pandas/core/indexes/interval.py
+index 3f72577c9..154f41bf0 100644
+--- a/pandas/core/indexes/interval.py
++++ b/pandas/core/indexes/interval.py
+@@ -59,7 +59,6 @@ from pandas.core.ops import get_op_result_name
+ if TYPE_CHECKING:
+     from pandas import CategoricalIndex  # noqa:F401
+
+-_VALID_CLOSED = {"left", "right", "both", "neither"}
+ _index_doc_kwargs = dict(ibase._index_doc_kwargs)
+
+ _index_doc_kwargs.update(
+diff --git a/pandas/core/reshape/merge.py b/pandas/core/reshape/merge.py
+index 030dec369..9f19ea9ae 100644
+--- a/pandas/core/reshape/merge.py
++++ b/pandas/core/reshape/merge.py
+@@ -859,7 +859,7 @@ class _MergeOperation:
+
+     def _get_join_indexers(self):
+         """ return the join indexers """
+-        return _get_join_indexers(
++        return get_join_indexers(
+             self.left_join_keys, self.right_join_keys, sort=self.sort, how=self.how
+         )
+
+@@ -1298,7 +1298,7 @@ class _MergeOperation:
+             raise ValueError("Not a valid argument for validate")
+
+
+-def _get_join_indexers(
++def get_join_indexers(
+     left_keys, right_keys, sort: bool = False, how: str = "inner", **kwargs
+ ):
+     """
+diff --git a/pandas/io/formats/printing.py b/pandas/io/formats/printing.py
+index edc6fbfff..0d2ca83f1 100644
+--- a/pandas/io/formats/printing.py
++++ b/pandas/io/formats/printing.py
+@@ -243,7 +243,7 @@ def pprint_thing_encoded(
+     return value.encode(encoding, errors)
+
+
+-def _enable_data_resource_formatter(enable: bool) -> None:
++def enable_data_resource_formatter(enable: bool) -> None:
+     if "IPython" not in sys.modules:
+         # definitely not in IPython
+         return
+diff --git a/pandas/tests/arrays/sparse/test_libsparse.py b/pandas/tests/arrays/sparse/test_libsparse.py
+index a2f861d37..2d6e657de 100644
+--- a/pandas/tests/arrays/sparse/test_libsparse.py
++++ b/pandas/tests/arrays/sparse/test_libsparse.py
+@@ -8,7 +8,7 @@ import pandas.util._test_decorators as td
+
+ from pandas import Series
+ import pandas._testing as tm
+-from pandas.core.arrays.sparse import BlockIndex, IntIndex, _make_index
++from pandas.core.arrays.sparse import BlockIndex, IntIndex, make_sparse_index
+
+ TEST_LENGTH = 20
+
+@@ -273,41 +273,43 @@ class TestSparseIndexIntersect:
+
+ class TestSparseIndexCommon:
+     def test_int_internal(self):
+-        idx = _make_index(4, np.array([2, 3], dtype=np.int32), kind="integer")
++        idx = make_sparse_index(4, np.array([2, 3], dtype=np.int32), kind="integer")
+         assert isinstance(idx, IntIndex)
+         assert idx.npoints == 2
+         tm.assert_numpy_array_equal(idx.indices, np.array([2, 3], dtype=np.int32))
+
+-        idx = _make_index(4, np.array([], dtype=np.int32), kind="integer")
++        idx = make_sparse_index(4, np.array([], dtype=np.int32), kind="integer")
+         assert isinstance(idx, IntIndex)
+         assert idx.npoints == 0
+         tm.assert_numpy_array_equal(idx.indices, np.array([], dtype=np.int32))
+
+-        idx = _make_index(4, np.array([0, 1, 2, 3], dtype=np.int32), kind="integer")
++        idx = make_sparse_index(
++            4, np.array([0, 1, 2, 3], dtype=np.int32), kind="integer"
++        )
+         assert isinstance(idx, IntIndex)
+         assert idx.npoints == 4
+         tm.assert_numpy_array_equal(idx.indices, np.array([0, 1, 2, 3], dtype=np.int32))
+
+     def test_block_internal(self):
+-        idx = _make_index(4, np.array([2, 3], dtype=np.int32), kind="block")
++        idx = make_sparse_index(4, np.array([2, 3], dtype=np.int32), kind="block")
+         assert isinstance(idx, BlockIndex)
+         assert idx.npoints == 2
+         tm.assert_numpy_array_equal(idx.blocs, np.array([2], dtype=np.int32))
+         tm.assert_numpy_array_equal(idx.blengths, np.array([2], dtype=np.int32))
+
+-        idx = _make_index(4, np.array([], dtype=np.int32), kind="block")
++        idx = make_sparse_index(4, np.array([], dtype=np.int32), kind="block")
+         assert isinstance(idx, BlockIndex)
+         assert idx.npoints == 0
+         tm.assert_numpy_array_equal(idx.blocs, np.array([], dtype=np.int32))
+         tm.assert_numpy_array_equal(idx.blengths, np.array([], dtype=np.int32))
+
+-        idx = _make_index(4, np.array([0, 1, 2, 3], dtype=np.int32), kind="block")
++        idx = make_sparse_index(4, np.array([0, 1, 2, 3], dtype=np.int32), kind="block")
+         assert isinstance(idx, BlockIndex)
+         assert idx.npoints == 4
+         tm.assert_numpy_array_equal(idx.blocs, np.array([0], dtype=np.int32))
+         tm.assert_numpy_array_equal(idx.blengths, np.array([4], dtype=np.int32))
+
+-        idx = _make_index(4, np.array([0, 2, 3], dtype=np.int32), kind="block")
++        idx = make_sparse_index(4, np.array([0, 2, 3], dtype=np.int32), kind="block")
+         assert isinstance(idx, BlockIndex)
+         assert idx.npoints == 3
+         tm.assert_numpy_array_equal(idx.blocs, np.array([0, 2], dtype=np.int32))
+@@ -315,7 +317,7 @@ class TestSparseIndexCommon:
+
+     def test_lookup(self):
+         for kind in ["integer", "block"]:
+-            idx = _make_index(4, np.array([2, 3], dtype=np.int32), kind=kind)
++            idx = make_sparse_index(4, np.array([2, 3], dtype=np.int32), kind=kind)
+             assert idx.lookup(-1) == -1
+             assert idx.lookup(0) == -1
+             assert idx.lookup(1) == -1
+@@ -323,12 +325,14 @@ class TestSparseIndexCommon:
+             assert idx.lookup(3) == 1
+             assert idx.lookup(4) == -1
+
+-            idx = _make_index(4, np.array([], dtype=np.int32), kind=kind)
++            idx = make_sparse_index(4, np.array([], dtype=np.int32), kind=kind)
+
+             for i in range(-1, 5):
+                 assert idx.lookup(i) == -1
+
+-            idx = _make_index(4, np.array([0, 1, 2, 3], dtype=np.int32), kind=kind)
++            idx = make_sparse_index(
++                4, np.array([0, 1, 2, 3], dtype=np.int32), kind=kind
++            )
+             assert idx.lookup(-1) == -1
+             assert idx.lookup(0) == 0
+             assert idx.lookup(1) == 1
+@@ -336,7 +340,7 @@ class TestSparseIndexCommon:
+             assert idx.lookup(3) == 3
+             assert idx.lookup(4) == -1
+
+-            idx = _make_index(4, np.array([0, 2, 3], dtype=np.int32), kind=kind)
++            idx = make_sparse_index(4, np.array([0, 2, 3], dtype=np.int32), kind=kind)
+             assert idx.lookup(-1) == -1
+             assert idx.lookup(0) == 0
+             assert idx.lookup(1) == -1
+@@ -346,7 +350,7 @@ class TestSparseIndexCommon:
+
+     def test_lookup_array(self):
+         for kind in ["integer", "block"]:
+-            idx = _make_index(4, np.array([2, 3], dtype=np.int32), kind=kind)
++            idx = make_sparse_index(4, np.array([2, 3], dtype=np.int32), kind=kind)
+
+             res = idx.lookup_array(np.array([-1, 0, 2], dtype=np.int32))
+             exp = np.array([-1, -1, 0], dtype=np.int32)
+@@ -356,11 +360,13 @@ class TestSparseIndexCommon:
+             exp = np.array([-1, 0, -1, 1], dtype=np.int32)
+             tm.assert_numpy_array_equal(res, exp)
+
+-            idx = _make_index(4, np.array([], dtype=np.int32), kind=kind)
++            idx = make_sparse_index(4, np.array([], dtype=np.int32), kind=kind)
+             res = idx.lookup_array(np.array([-1, 0, 2, 4], dtype=np.int32))
+             exp = np.array([-1, -1, -1, -1], dtype=np.int32)
+
+-            idx = _make_index(4, np.array([0, 1, 2, 3], dtype=np.int32), kind=kind)
++            idx = make_sparse_index(
++                4, np.array([0, 1, 2, 3], dtype=np.int32), kind=kind
++            )
+             res = idx.lookup_array(np.array([-1, 0, 2], dtype=np.int32))
+             exp = np.array([-1, 0, 2], dtype=np.int32)
+             tm.assert_numpy_array_equal(res, exp)
+@@ -369,7 +375,7 @@ class TestSparseIndexCommon:
+             exp = np.array([-1, 2, 1, 3], dtype=np.int32)
+             tm.assert_numpy_array_equal(res, exp)
+
+-            idx = _make_index(4, np.array([0, 2, 3], dtype=np.int32), kind=kind)
++            idx = make_sparse_index(4, np.array([0, 2, 3], dtype=np.int32), kind=kind)
+             res = idx.lookup_array(np.array([2, 1, 3, 0], dtype=np.int32))
+             exp = np.array([1, -1, 2, 0], dtype=np.int32)
+             tm.assert_numpy_array_equal(res, exp)
+@@ -402,25 +408,25 @@ class TestSparseIndexCommon:
+
+ class TestBlockIndex:
+     def test_block_internal(self):
+-        idx = _make_index(4, np.array([2, 3], dtype=np.int32), kind="block")
++        idx = make_sparse_index(4, np.array([2, 3], dtype=np.int32), kind="block")
+         assert isinstance(idx, BlockIndex)
+         assert idx.npoints == 2
+         tm.assert_numpy_array_equal(idx.blocs, np.array([2], dtype=np.int32))
+         tm.assert_numpy_array_equal(idx.blengths, np.array([2], dtype=np.int32))
+
+-        idx = _make_index(4, np.array([], dtype=np.int32), kind="block")
++        idx = make_sparse_index(4, np.array([], dtype=np.int32), kind="block")
+         assert isinstance(idx, BlockIndex)
+         assert idx.npoints == 0
+         tm.assert_numpy_array_equal(idx.blocs, np.array([], dtype=np.int32))
+         tm.assert_numpy_array_equal(idx.blengths, np.array([], dtype=np.int32))
+
+-        idx = _make_index(4, np.array([0, 1, 2, 3], dtype=np.int32), kind="block")
++        idx = make_sparse_index(4, np.array([0, 1, 2, 3], dtype=np.int32), kind="block")
+         assert isinstance(idx, BlockIndex)
+         assert idx.npoints == 4
+         tm.assert_numpy_array_equal(idx.blocs, np.array([0], dtype=np.int32))
+         tm.assert_numpy_array_equal(idx.blengths, np.array([4], dtype=np.int32))
+
+-        idx = _make_index(4, np.array([0, 2, 3], dtype=np.int32), kind="block")
++        idx = make_sparse_index(4, np.array([0, 2, 3], dtype=np.int32), kind="block")
+         assert isinstance(idx, BlockIndex)
+         assert idx.npoints == 3
+         tm.assert_numpy_array_equal(idx.blocs, np.array([0, 2], dtype=np.int32))
+@@ -428,7 +434,7 @@ class TestBlockIndex:
+
+     def test_make_block_boundary(self):
+         for i in [5, 10, 100, 101]:
+-            idx = _make_index(i, np.arange(0, i, 2, dtype=np.int32), kind="block")
++            idx = make_sparse_index(i, np.arange(0, i, 2, dtype=np.int32), kind="block")
+
+             exp = np.arange(0, i, 2, dtype=np.int32)
+             tm.assert_numpy_array_equal(idx.blocs, exp)
+@@ -514,17 +520,19 @@ class TestIntIndex:
+             IntIndex(length=5, indices=[1, 3, 3])
+
+     def test_int_internal(self):
+-        idx = _make_index(4, np.array([2, 3], dtype=np.int32), kind="integer")
++        idx = make_sparse_index(4, np.array([2, 3], dtype=np.int32), kind="integer")
+         assert isinstance(idx, IntIndex)
+         assert idx.npoints == 2
+         tm.assert_numpy_array_equal(idx.indices, np.array([2, 3], dtype=np.int32))
+
+-        idx = _make_index(4, np.array([], dtype=np.int32), kind="integer")
++        idx = make_sparse_index(4, np.array([], dtype=np.int32), kind="integer")
+         assert isinstance(idx, IntIndex)
+         assert idx.npoints == 0
+         tm.assert_numpy_array_equal(idx.indices, np.array([], dtype=np.int32))
+
+-        idx = _make_index(4, np.array([0, 1, 2, 3], dtype=np.int32), kind="integer")
++        idx = make_sparse_index(
++            4, np.array([0, 1, 2, 3], dtype=np.int32), kind="integer"
++        )
+         assert isinstance(idx, IntIndex)
+         assert idx.npoints == 4
+         tm.assert_numpy_array_equal(idx.indices, np.array([0, 1, 2, 3], dtype=np.int32))
+diff --git a/pandas/tests/computation/test_compat.py b/pandas/tests/computation/test_compat.py
+index ead102f53..9fc3ed480 100644
+--- a/pandas/tests/computation/test_compat.py
++++ b/pandas/tests/computation/test_compat.py
+@@ -5,7 +5,7 @@ import pytest
+ from pandas.compat._optional import VERSIONS
+
+ import pandas as pd
+-from pandas.core.computation.engines import _engines
++from pandas.core.computation.engines import ENGINES
+ import pandas.core.computation.expr as expr
+
+
+@@ -26,8 +26,8 @@ def test_compat():
+         pytest.skip("not testing numexpr version compat")
+
+
+-@pytest.mark.parametrize("engine", _engines)
+-@pytest.mark.parametrize("parser", expr._parsers)
++@pytest.mark.parametrize("engine", ENGINES)
++@pytest.mark.parametrize("parser", expr.PARSERS)
+ def test_invalid_numexpr_version(engine, parser):
+     def testit():
+         a, b = 1, 2  # noqa
+diff --git a/pandas/tests/computation/test_eval.py b/pandas/tests/computation/test_eval.py
+index 72dc04e68..cca64a6bf 100644
+--- a/pandas/tests/computation/test_eval.py
++++ b/pandas/tests/computation/test_eval.py
+@@ -19,7 +19,7 @@ from pandas import DataFrame, Series, compat, date_range
+ import pandas._testing as tm
+ from pandas.core.computation import pytables
+ from pandas.core.computation.check import NUMEXPR_VERSION
+-from pandas.core.computation.engines import NumExprClobberingError, _engines
++from pandas.core.computation.engines import ENGINES, NumExprClobberingError
+ import pandas.core.computation.expr as expr
+ from pandas.core.computation.expr import (
+     BaseExprVisitor,
+@@ -46,14 +46,14 @@ from pandas.core.computation.ops import (
+                 f"installed->{NUMEXPR_INSTALLED}",
+             ),
+         )
+-        for engine in _engines
++        for engine in ENGINES
+     )
+ )  # noqa
+ def engine(request):
+     return request.param
+
+
+-@pytest.fixture(params=expr._parsers)
++@pytest.fixture(params=expr.PARSERS)
+ def parser(request):
+     return request.param
+
+@@ -77,7 +77,7 @@ def unary_fns_for_ne():
+
+
+ def engine_has_neg_frac(engine):
+-    return _engines[engine].has_neg_frac
++    return ENGINES[engine].has_neg_frac
+
+
+ def _eval_single_bin(lhs, cmp1, rhs, engine):
+@@ -168,7 +168,7 @@ class TestEvalNumexprPandas:
+     def setup_method(self, method):
+         self.setup_ops()
+         self.setup_data()
+-        self.current_engines = (engine for engine in _engines if engine != self.engine)
++        self.current_engines = (engine for engine in ENGINES if engine != self.engine)
+
+     def teardown_method(self, method):
+         del self.lhses, self.rhses, self.scalar_rhses, self.scalar_lhses
+@@ -1921,7 +1921,7 @@ _parsers: Dict[str, Type[BaseExprVisitor]] = {
+ }
+
+
+-@pytest.mark.parametrize("engine", _engines)
++@pytest.mark.parametrize("engine", ENGINES)
+ @pytest.mark.parametrize("parser", _parsers)
+ def test_disallowed_nodes(engine, parser):
+     VisitorClass = _parsers[parser]
\ No newline at end of file