From 10465ea620236481b57d547859041853a0af864f Mon Sep 17 00:00:00 2001
From: Dimitri Papadopoulos
 <3234522+DimitriPapadopoulos@users.noreply.github.com>
Date: Wed, 28 May 2025 18:29:10 +0200
Subject: [PATCH 1/2] Apply ruff/flynt rule FLY002

FLY002 Consider f-string instead of string join
---
 xarray/convert.py                   | 2 +-
 xarray/core/formatting.py           | 2 +-
 xarray/tests/test_cftime_offsets.py | 4 ++--
 3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/xarray/convert.py b/xarray/convert.py
index 29d8f9650e3..b6811797a2e 100644
--- a/xarray/convert.py
+++ b/xarray/convert.py
@@ -138,7 +138,7 @@ def _iris_cell_methods_to_str(cell_methods_obj):
             f"interval: {interval}" for interval in cell_method.intervals
         )
         comments = " ".join(f"comment: {comment}" for comment in cell_method.comments)
-        extra = " ".join([intervals, comments]).strip()
+        extra = f"{intervals} {comments}".strip()
         if extra:
             extra = f" ({extra})"
         cell_methods.append(names + cell_method.method + extra)
diff --git a/xarray/core/formatting.py b/xarray/core/formatting.py
index fb672997706..69359462cde 100644
--- a/xarray/core/formatting.py
+++ b/xarray/core/formatting.py
@@ -894,7 +894,7 @@ def extra_items_repr(extra_keys, mapping, ab_side, kwargs):
                     attrs_summary.append(attr_s)
 
                 temp = [
-                    "\n".join([var_s, attr_s]) if attr_s else var_s
+                    f"{var_s}\n{attr_s}" if attr_s else var_s
                     for var_s, attr_s in zip(temp, attrs_summary, strict=True)
                 ]
 
diff --git a/xarray/tests/test_cftime_offsets.py b/xarray/tests/test_cftime_offsets.py
index 75269286007..de02d431bfa 100644
--- a/xarray/tests/test_cftime_offsets.py
+++ b/xarray/tests/test_cftime_offsets.py
@@ -274,7 +274,7 @@ def test_to_offset_annual(month_label, month_int, multiple, offset_str):
     freq = offset_str
     offset_type = _ANNUAL_OFFSET_TYPES[offset_str]
     if month_label:
-        freq = "-".join([freq, month_label])
+        freq = f"{freq}-{month_label}"
     if multiple:
         freq = f"{multiple}{freq}"
     result = to_offset(freq)
@@ -303,7 +303,7 @@ def test_to_offset_quarter(month_label, month_int, multiple, offset_str):
     freq = offset_str
     offset_type = _QUARTER_OFFSET_TYPES[offset_str]
     if month_label:
-        freq = "-".join([freq, month_label])
+        freq = f"{freq}-{month_label}"
     if multiple:
         freq = f"{multiple}{freq}"
     result = to_offset(freq)

From ad1c4527d0a7bb024412b1b54a40f380bb39c740 Mon Sep 17 00:00:00 2001
From: Dimitri Papadopoulos
 <3234522+DimitriPapadopoulos@users.noreply.github.com>
Date: Wed, 28 May 2025 18:30:08 +0200
Subject: [PATCH 2/2] Enforce ruff/flynt rules (FLY)

---
 pyproject.toml | 1 +
 1 file changed, 1 insertion(+)

diff --git a/pyproject.toml b/pyproject.toml
index a99393de886..c980c204b5f 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -255,6 +255,7 @@ extend-select = [
   "PIE",  # flake8-pie
   "TID",  # flake8-tidy-imports (absolute imports)
   "PYI",  # flake8-pyi
+  "FLY",  # flynt
   "I",    # isort
   "PERF", # Perflint
   "W",    # pycodestyle warnings