Merge pull request matplotlib#29477 from QuLogic/arm-ci

ci: Add an ARM Linux test workflow

Author: timhoffm

.github/workflows/tests.yml

@@ -78,7 +78,7 @@ jobs:
             # https://bugreports.qt.io/projects/PYSIDE/issues/PYSIDE-2346
             pyside6-ver: '!=6.5.1'
             extra-requirements: '-r requirements/testing/extra.txt'
-          - os: ubuntu-22.04
+          - os: ubuntu-22.04-arm
             python-version: '3.12'
             # https://www.riverbankcomputing.com/pipermail/pyqt/2023-November/045606.html
             pyqt6-ver: '!=6.6.0'
@@ -282,10 +282,13 @@ jobs:
               echo 'PyGObject 3 is available' || echo 'PyGObject 3 is not available'
             )
 
-          python -mpip install --upgrade pyqt5${{ matrix.pyqt5-ver }} &&
-            python -c 'import PyQt5.QtCore' &&
-            echo 'PyQt5 is available' ||
-            echo 'PyQt5 is not available'
+          # PyQt5 does not have any wheels for ARM on Linux.
+          if [[ "${{ matrix.os }}" != 'ubuntu-22.04-arm' ]]; then
+            python -mpip install --upgrade --only-binary :all: pyqt5${{ matrix.pyqt5-ver }} &&
+              python -c 'import PyQt5.QtCore' &&
+              echo 'PyQt5 is available' ||
+              echo 'PyQt5 is not available'
+          fi
           # Even though PySide2 wheels can be installed on Python 3.12+, they are broken and since PySide2 is
           # deprecated, they are unlikely to be fixed. For the same deprecation reason, there are no wheels
           # on M1 macOS, so don't bother there either.
@@ -296,16 +299,16 @@ jobs:
               echo 'PySide2 is available' ||
               echo 'PySide2 is not available'
           fi
-          python -mpip install --upgrade pyqt6${{ matrix.pyqt6-ver }} &&
+          python -mpip install --upgrade --only-binary :all: pyqt6${{ matrix.pyqt6-ver }} &&
             python -c 'import PyQt6.QtCore' &&
             echo 'PyQt6 is available' ||
             echo 'PyQt6 is not available'
-          python -mpip install --upgrade pyside6${{ matrix.pyside6-ver }} &&
+          python -mpip install --upgrade --only-binary :all: pyside6${{ matrix.pyside6-ver }} &&
             python -c 'import PySide6.QtCore' &&
             echo 'PySide6 is available' ||
             echo 'PySide6 is not available'
 
-          python -mpip install --upgrade \
+          python -mpip install --upgrade --only-binary :all: \
             -f "https://extras.wxpython.org/wxPython4/extras/linux/gtk3/${{ matrix.os }}" \
             wxPython &&
             python -c 'import wx' &&

lib/matplotlib/tests/test_axes.py

@@ -1454,7 +1454,8 @@ def test_pcolormesh_small():
 
 
 @image_comparison(['pcolormesh_alpha'], extensions=["png", "pdf"],
-                  remove_text=True)
+                  remove_text=True,
+                  tol=0.2 if platform.machine() == "aarch64" else 0)
 def test_pcolormesh_alpha():
     # Remove this line when this test image is regenerated.
     plt.rcParams['pcolormesh.snap'] = False
@@ -9162,8 +9163,10 @@ def test_zorder_and_explicit_rasterization():
         fig.savefig(b, format='pdf')
 
 
-@image_comparison(["preset_clip_paths.png"], remove_text=True, style="mpl20",
-                  tol=0.027 if platform.machine() in ("arm64", "ppc64le") else 0)
+@image_comparison(
+    ["preset_clip_paths.png"],
+    remove_text=True, style="mpl20",
+    tol=0.027 if platform.machine() in ("aarch64", "arm64", "ppc64le") else 0)
 def test_preset_clip_paths():
     fig, ax = plt.subplots()