diff --git a/pandas/__init__.py b/pandas/__init__.py
index cd697b757a26a..d6f3458b4d604 100644
--- a/pandas/__init__.py
+++ b/pandas/__init__.py
@@ -24,6 +24,7 @@
     _np_version_under1p15,
     _np_version_under1p16,
     _np_version_under1p17,
+    _np_version_under1p18,
 )
 
 try:
diff --git a/pandas/tests/api/test_api.py b/pandas/tests/api/test_api.py
index 1282aa6edd538..85e38d58a6c57 100644
--- a/pandas/tests/api/test_api.py
+++ b/pandas/tests/api/test_api.py
@@ -189,6 +189,7 @@ class TestPDApi(Base):
         "_np_version_under1p15",
         "_np_version_under1p16",
         "_np_version_under1p17",
+        "_np_version_under1p18",
         "_tslib",
         "_typing",
         "_version",
diff --git a/pandas/tests/indexes/test_numpy_compat.py b/pandas/tests/indexes/test_numpy_compat.py
index 6626ccf4a29f8..3d24c70afdda2 100644
--- a/pandas/tests/indexes/test_numpy_compat.py
+++ b/pandas/tests/indexes/test_numpy_compat.py
@@ -6,9 +6,11 @@
     Float64Index,
     Index,
     Int64Index,
+    PeriodIndex,
     TimedeltaIndex,
     UInt64Index,
     _np_version_under1p17,
+    _np_version_under1p18,
 )
 from pandas.core.indexes.datetimelike import DatetimeIndexOpsMixin
 import pandas.util.testing as tm
@@ -80,18 +82,22 @@ def test_numpy_ufuncs_other(indices, func):
     idx = indices
     if isinstance(idx, (DatetimeIndex, TimedeltaIndex)):
 
-        # ok under numpy >= 1.17
-        if not _np_version_under1p17 and func in [np.isfinite]:
+        if not _np_version_under1p18 and func in [np.isfinite, np.isinf, np.isnan]:
+            # numpy 1.18(dev) changed isinf and isnan to not raise on dt64/tfd64
+            result = func(idx)
+            assert isinstance(result, np.ndarray)
+
+        elif not _np_version_under1p17 and func in [np.isfinite]:
+            # ok under numpy >= 1.17
             # Results in bool array
             result = func(idx)
             assert isinstance(result, np.ndarray)
-            assert not isinstance(result, Index)
         else:
             # raise TypeError or ValueError (PeriodIndex)
             with pytest.raises(Exception):
                 func(idx)
 
-    elif isinstance(idx, DatetimeIndexOpsMixin):
+    elif isinstance(idx, PeriodIndex):
         # raise TypeError or ValueError (PeriodIndex)
         with pytest.raises(Exception):
             func(idx)
diff --git a/pandas/tests/reshape/test_concat.py b/pandas/tests/reshape/test_concat.py
index 667fe689861be..bb8339439d339 100644
--- a/pandas/tests/reshape/test_concat.py
+++ b/pandas/tests/reshape/test_concat.py
@@ -765,13 +765,15 @@ def test_concat_join_axes_deprecated(self, axis):
         )
 
         expected = pd.concat([one, two], axis=1, sort=False).reindex(index=two.index)
-        result = pd.concat([one, two], axis=1, sort=False, join_axes=[two.index])
+        with tm.assert_produces_warning(FutureWarning):
+            result = pd.concat([one, two], axis=1, sort=False, join_axes=[two.index])
         tm.assert_frame_equal(result, expected)
 
         expected = pd.concat([one, two], axis=0, sort=False).reindex(
             columns=two.columns
         )
-        result = pd.concat([one, two], axis=0, sort=False, join_axes=[two.columns])
+        with tm.assert_produces_warning(FutureWarning):
+            result = pd.concat([one, two], axis=0, sort=False, join_axes=[two.columns])
         tm.assert_frame_equal(result, expected)