From 1fc24f82debe1aa4c90a33d058ab5b905654f234 Mon Sep 17 00:00:00 2001
From: Maximilian Roos <m@maxroos.com>
Date: Tue, 17 Oct 2023 11:48:47 -0700
Subject: [PATCH]

---
 xarray/core/rolling_exp.py | 19 ++++++++++---------
 xarray/tests/__init__.py   |  2 +-
 2 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/xarray/core/rolling_exp.py b/xarray/core/rolling_exp.py
index 7c747201856..d1e613e98a2 100644
--- a/xarray/core/rolling_exp.py
+++ b/xarray/core/rolling_exp.py
@@ -4,6 +4,7 @@
 from typing import Any, Generic
 
 import numpy as np
+from packaging.version import Version
 
 from xarray.core.computation import apply_ufunc
 from xarray.core.options import _get_keep_attrs
@@ -14,9 +15,9 @@
     import numbagg
     from numbagg import move_exp_nanmean, move_exp_nansum
 
-    has_numbagg = numbagg.__version__
+    has_numbagg: Version | None = Version(numbagg.__version__)
 except ImportError:
-    has_numbagg = False
+    has_numbagg = None
 
 
 def _get_alpha(
@@ -99,15 +100,15 @@ def __init__(
         window_type: str = "span",
         min_weight: float = 0.0,
     ):
-        if has_numbagg is False:
+        if has_numbagg is None:
             raise ImportError(
                 "numbagg >= 0.2.1 is required for rolling_exp but currently numbagg is not installed"
             )
-        elif has_numbagg < "0.2.1":
+        elif has_numbagg < Version("0.2.1"):
             raise ImportError(
                 f"numbagg >= 0.2.1 is required for `rolling_exp` but currently version {has_numbagg} is installed"
             )
-        elif has_numbagg < "0.3.1" and min_weight > 0:
+        elif has_numbagg < Version("0.3.1") and min_weight > 0:
             raise ImportError(
                 f"numbagg >= 0.3.1 is required for `min_weight > 0` within `.rolling_exp` but currently version {has_numbagg} is installed"
             )
@@ -210,7 +211,7 @@ def std(self) -> T_DataWithCoords:
         Dimensions without coordinates: x
         """
 
-        if has_numbagg is False or has_numbagg < "0.4.0":
+        if has_numbagg is None or has_numbagg < Version("0.4.0"):
             raise ImportError(
                 f"numbagg >= 0.4.0 is required for rolling_exp().std(), currently {has_numbagg} is installed"
             )
@@ -242,7 +243,7 @@ def var(self) -> T_DataWithCoords:
         Dimensions without coordinates: x
         """
 
-        if has_numbagg is False or has_numbagg < "0.4.0":
+        if has_numbagg is None or has_numbagg < Version("0.4.0"):
             raise ImportError(
                 f"numbagg >= 0.4.0 is required for rolling_exp().var(), currently {has_numbagg} is installed"
             )
@@ -274,7 +275,7 @@ def cov(self, other: T_DataWithCoords) -> T_DataWithCoords:
         Dimensions without coordinates: x
         """
 
-        if has_numbagg is False or has_numbagg < "0.4.0":
+        if has_numbagg is None or has_numbagg < Version("0.4.0"):
             raise ImportError(
                 f"numbagg >= 0.4.0 is required for rolling_exp().cov(), currently {has_numbagg} is installed"
             )
@@ -307,7 +308,7 @@ def corr(self, other: T_DataWithCoords) -> T_DataWithCoords:
         Dimensions without coordinates: x
         """
 
-        if has_numbagg is False or has_numbagg < "0.4.0":
+        if has_numbagg is None or has_numbagg < Version("0.4.0"):
             raise ImportError(
                 f"numbagg >= 0.4.0 is required for rolling_exp().cov(), currently {has_numbagg} is installed"
             )
diff --git a/xarray/tests/__init__.py b/xarray/tests/__init__.py
index 7e1b964ecba..07ba0be6a8c 100644
--- a/xarray/tests/__init__.py
+++ b/xarray/tests/__init__.py
@@ -75,7 +75,7 @@ def _importorskip(
 has_zarr, requires_zarr = _importorskip("zarr")
 has_fsspec, requires_fsspec = _importorskip("fsspec")
 has_iris, requires_iris = _importorskip("iris")
-has_numbagg, requires_numbagg = _importorskip("numbagg")
+has_numbagg, requires_numbagg = _importorskip("numbagg", "0.4.0")
 has_seaborn, requires_seaborn = _importorskip("seaborn")
 has_sparse, requires_sparse = _importorskip("sparse")
 has_cupy, requires_cupy = _importorskip("cupy")