CI: Test on Linux arm64 runners

.github/workflows/ci_tests.yaml

@@ -57,12 +57,14 @@ jobs:
       fail-fast: false
       matrix:
         python-version: ['3.11', '3.13']
-        os: [ubuntu-latest, macos-latest, windows-latest]
+        os: [ubuntu-latest, ubuntu-24.04-arm, macos-latest, windows-latest]
         # Is it a draft Pull Request (true or false)?
         isDraft:
           - ${{ github.event.pull_request.draft }}
-        # Only run three jobs on Ubuntu for draft PRs
+        # Only run jobs on Ubuntu for draft PRs
         exclude:
+          - os: ubuntu-24.04-arm
+            isDraft: true
           - os: macos-latest
             isDraft: true
           - os: windows-latest

.github/workflows/ci_tests_dev.yaml

@@ -36,7 +36,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-24.04, macos-15, windows-2025]
+        os: [ubuntu-24.04, ubuntu-24.04-arm, macos-15, windows-2025]
         gmt_git_ref: [master]
     timeout-minutes: 30
     defaults:

.github/workflows/ci_tests_legacy.yaml

@@ -34,7 +34,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-22.04, macos-13, windows-2019]
+        os: [ubuntu-22.04, ubuntu-22.04-arm, macos-13, windows-2019]
         gmt_version: ['6.4']
     timeout-minutes: 30
     defaults:

pygmt/tests/test_contour.py

@@ -2,6 +2,7 @@
 Test Figure.contour.
 """
 
+import platform
 from pathlib import Path
 
 import numpy as np
@@ -30,6 +31,7 @@ def fixture_region():
 
 
 @pytest.mark.mpl_image_compare
+@pytest.mark.xfail(platform.machine() == "aarch64", reason="Fails on Linux ARM64")
 def test_contour_vec(region):
     """
     Plot an x-centered gaussian kernel with different y scale.
@@ -130,6 +132,7 @@ def test_contour_multiple_levels(region):
 
 
 @pytest.mark.mpl_image_compare(filename="test_contour_vec.png")
+@pytest.mark.xfail(platform.machine() == "aarch64", reason="Fails on Linux ARM64")
 def test_contour_incols_transposed_data(region):
     """
     Make sure that transposing the data matrix still produces a correct result with

pygmt/tests/test_x2sys_cross.py

@@ -3,6 +3,7 @@
 """
 
 import copy
+import platform
 import sys
 from pathlib import Path
 from tempfile import TemporaryDirectory
@@ -270,7 +271,7 @@ def test_x2sys_cross_region_interpolation_numpoints():
         )
 
         assert isinstance(output, pd.DataFrame)
-        if sys.platform == "darwin":
+        if platform.machine() in {"aarch64", "arm64"}:
             assert output.shape == (3894, 12)
             # Check crossover errors (z_X) and mean value of observables (z_M)
             npt.assert_allclose(output.z_X.mean(), -138.23215, rtol=1e-4)
@@ -298,7 +299,7 @@ def test_x2sys_cross_trackvalues():
         output = x2sys_cross(tracks=["@tut_ship.xyz"], tag=tag, trackvalues=True)
 
         assert isinstance(output, pd.DataFrame)
-        if sys.platform == "darwin":
+        if platform.machine() in {"aarch64", "arm64"}:
             assert output.shape == (14374, 12)
             # Check mean of track 1 values (z_1) and track 2 values (z_2)
             npt.assert_allclose(output.z_1.mean(), -2422.973372, rtol=1e-4)