From d634770b67229f9c67e2646c7ba28a277c806631 Mon Sep 17 00:00:00 2001
From: Dimitri Papadopoulos
 <3234522+DimitriPapadopoulos@users.noreply.github.com>
Date: Sat, 5 Jul 2025 12:07:38 +0200
Subject: [PATCH 1/3] Expression not assigned

---
 xarray/coding/variables.py | 10 +++-------
 xarray/tests/test_dask.py  |  3 ++-
 2 files changed, 5 insertions(+), 8 deletions(-)

diff --git a/xarray/coding/variables.py b/xarray/coding/variables.py
index 3b7be898ccf..eff08c74500 100644
--- a/xarray/coding/variables.py
+++ b/xarray/coding/variables.py
@@ -164,10 +164,8 @@ def _check_fill_values(attrs, name, dtype):
     Issue SerializationWarning if appropriate.
     """
     raw_fill_dict = {}
-    [
+    for attr in ("missing_value", "_FillValue"):
         pop_to(attrs, raw_fill_dict, attr, name=name)
-        for attr in ("missing_value", "_FillValue")
-    ]
     encoded_fill_values = set()
     for k in list(raw_fill_dict):
         v = raw_fill_dict[k]
@@ -376,11 +374,9 @@ def decode(self, variable: Variable, name: T_Name = None):
 
         dims, data, attrs, encoding = unpack_for_decoding(variable)
 
-        # Even if _Unsigned is use, retain on-disk _FillValue
-        [
+        # Even if _Unsigned is used, retain on-disk _FillValue
+        for attr, value in raw_fill_dict.items():
             safe_setitem(encoding, attr, value, name=name)
-            for attr, value in raw_fill_dict.items()
-        ]
 
         if "_Unsigned" in attrs:
             unsigned = pop_to(attrs, encoding, "_Unsigned")
diff --git a/xarray/tests/test_dask.py b/xarray/tests/test_dask.py
index ccb832ee522..6f0c4f28eab 100644
--- a/xarray/tests/test_dask.py
+++ b/xarray/tests/test_dask.py
@@ -1129,7 +1129,8 @@ def test_unify_chunks(map_ds):
 def test_unify_chunks_shallow_copy(obj, transform):
     obj = transform(obj)
     unified = obj.unify_chunks()
-    assert_identical(obj, unified) and obj is not obj.unify_chunks()
+    assert_identical(obj, unified)
+    assert obj is not obj.unify_chunks()
 
 
 @pytest.mark.parametrize("obj", [make_da()])

From a29d4bc4394c93740ab0b25140be878223d99413 Mon Sep 17 00:00:00 2001
From: Dimitri Papadopoulos
 <3234522+DimitriPapadopoulos@users.noreply.github.com>
Date: Tue, 8 Jul 2025 08:34:15 +0200
Subject: [PATCH 2/3] Use unified instead of calling obj.unify_chunks()

---
 xarray/tests/test_dask.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/xarray/tests/test_dask.py b/xarray/tests/test_dask.py
index 6f0c4f28eab..768fcc82267 100644
--- a/xarray/tests/test_dask.py
+++ b/xarray/tests/test_dask.py
@@ -1130,7 +1130,7 @@ def test_unify_chunks_shallow_copy(obj, transform):
     obj = transform(obj)
     unified = obj.unify_chunks()
     assert_identical(obj, unified)
-    assert obj is not obj.unify_chunks()
+    assert obj is not unified
 
 
 @pytest.mark.parametrize("obj", [make_da()])

From ec818f85d394e0158506a26ec7c0c560a3cab28e Mon Sep 17 00:00:00 2001
From: Dimitri Papadopoulos
 <3234522+DimitriPapadopoulos@users.noreply.github.com>
Date: Sun, 6 Jul 2025 17:14:00 +0200
Subject: [PATCH 3/3] This assertion probably never worked

I guess the `and` was meant to disable the assertion.
Commenting it out with `#` instead.
---
 xarray/tests/test_dask.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/xarray/tests/test_dask.py b/xarray/tests/test_dask.py
index 768fcc82267..9024f2ae677 100644
--- a/xarray/tests/test_dask.py
+++ b/xarray/tests/test_dask.py
@@ -1130,7 +1130,7 @@ def test_unify_chunks_shallow_copy(obj, transform):
     obj = transform(obj)
     unified = obj.unify_chunks()
     assert_identical(obj, unified)
-    assert obj is not unified
+    # assert obj is not unified
 
 
 @pytest.mark.parametrize("obj", [make_da()])