From eb42d8637ba5891aa806fa6b0ed73835c16b2741 Mon Sep 17 00:00:00 2001
From: David Stansby <dstansby@gmail.com>
Date: Sun, 28 Sep 2025 14:08:57 +0100
Subject: [PATCH] Backport PR #30612: MNT: update black pin

---
 environment.yml                     |  2 +-
 lib/matplotlib/pyplot.py            | 30 ++++++++++++++---------------
 lib/matplotlib/tests/test_pyplot.py |  2 +-
 requirements/testing/all.txt        |  2 +-
 4 files changed, 18 insertions(+), 18 deletions(-)

diff --git a/environment.yml b/environment.yml
index d95cab0509ff..bea37db1e10f 100644
--- a/environment.yml
+++ b/environment.yml
@@ -51,7 +51,7 @@ dependencies:
       - sphinxcontrib-video>=0.2.1
       - pikepdf
   # testing
-  - black<24
+  - black<26
   - coverage
   - flake8>=3.8,<7.2
   - flake8-docstrings>=1.4.0
diff --git a/lib/matplotlib/pyplot.py b/lib/matplotlib/pyplot.py
index 2dd8e76d98b4..9cca3b0370a6 100644
--- a/lib/matplotlib/pyplot.py
+++ b/lib/matplotlib/pyplot.py
@@ -3145,8 +3145,9 @@ def cohere(
     NFFT: int = 256,
     Fs: float = 2,
     Fc: int = 0,
-    detrend: Literal["none", "mean", "linear"]
-    | Callable[[ArrayLike], ArrayLike] = mlab.detrend_none,
+    detrend: (
+        Literal["none", "mean", "linear"] | Callable[[ArrayLike], ArrayLike]
+    ) = mlab.detrend_none,
     window: Callable[[ArrayLike], ArrayLike] | ArrayLike = mlab.window_hanning,
     noverlap: int = 0,
     pad_to: int | None = None,
@@ -3203,9 +3204,9 @@ def csd(
     NFFT: int | None = None,
     Fs: float | None = None,
     Fc: int | None = None,
-    detrend: Literal["none", "mean", "linear"]
-    | Callable[[ArrayLike], ArrayLike]
-    | None = None,
+    detrend: (
+        Literal["none", "mean", "linear"] | Callable[[ArrayLike], ArrayLike] | None
+    ) = None,
     window: Callable[[ArrayLike], ArrayLike] | ArrayLike | None = None,
     noverlap: int | None = None,
     pad_to: int | None = None,
@@ -3876,9 +3877,9 @@ def psd(
     NFFT: int | None = None,
     Fs: float | None = None,
     Fc: int | None = None,
-    detrend: Literal["none", "mean", "linear"]
-    | Callable[[ArrayLike], ArrayLike]
-    | None = None,
+    detrend: (
+        Literal["none", "mean", "linear"] | Callable[[ArrayLike], ArrayLike] | None
+    ) = None,
     window: Callable[[ArrayLike], ArrayLike] | ArrayLike | None = None,
     noverlap: int | None = None,
     pad_to: int | None = None,
@@ -3986,9 +3987,9 @@ def specgram(
     NFFT: int | None = None,
     Fs: float | None = None,
     Fc: int | None = None,
-    detrend: Literal["none", "mean", "linear"]
-    | Callable[[ArrayLike], ArrayLike]
-    | None = None,
+    detrend: (
+        Literal["none", "mean", "linear"] | Callable[[ArrayLike], ArrayLike] | None
+    ) = None,
     window: Callable[[ArrayLike], ArrayLike] | ArrayLike | None = None,
     noverlap: int | None = None,
     cmap: str | Colormap | None = None,
@@ -4299,10 +4300,9 @@ def violinplot(
     showmedians: bool = False,
     quantiles: Sequence[float | Sequence[float]] | None = None,
     points: int = 100,
-    bw_method: Literal["scott", "silverman"]
-    | float
-    | Callable[[GaussianKDE], float]
-    | None = None,
+    bw_method: (
+        Literal["scott", "silverman"] | float | Callable[[GaussianKDE], float] | None
+    ) = None,
     side: Literal["both", "low", "high"] = "both",
     *,
     data=None,
diff --git a/lib/matplotlib/tests/test_pyplot.py b/lib/matplotlib/tests/test_pyplot.py
index 1aaa8dd93ca2..46bd6e456d32 100644
--- a/lib/matplotlib/tests/test_pyplot.py
+++ b/lib/matplotlib/tests/test_pyplot.py
@@ -12,7 +12,7 @@
 
 
 def test_pyplot_up_to_date(tmp_path):
-    pytest.importorskip("black")
+    pytest.importorskip("black", minversion="24.1")
 
     gen_script = Path(mpl.__file__).parents[2] / "tools/boilerplate.py"
     if not gen_script.exists():
diff --git a/requirements/testing/all.txt b/requirements/testing/all.txt
index a41073bdf47e..dd1dbf3f29fd 100644
--- a/requirements/testing/all.txt
+++ b/requirements/testing/all.txt
@@ -1,6 +1,6 @@
 # pip requirements for all the CI builds
 
-black<24
+black<26
 certifi
 coverage!=6.3
 psutil