CHORE: Use matplotlib Agg backend when testing

doc/source/conf.py

@@ -277,12 +277,17 @@ def setup(app):
     # Must be less than or equal to the XVFB window size
     pyvista.global_theme["window_size"] = np.array([1024, 768])
 
-    # suppress annoying matplotlib bug
+    # Suppress annoying matplotlib bug
     warnings.filterwarnings(
         "ignore",
         category=UserWarning,
         message="Matplotlib is currently using agg, which is a non-GUI backend, so it cannot show the figure.",
     )
+    warnings.filterwarnings(
+        "ignore",
+        category=UserWarning,
+        message="FigureCanvasAgg is non-interactive, and thus cannot be shown",
+    )
 
     extensions.append("sphinx_gallery.gen_gallery")
     sphinx_gallery_conf = {

pyaedt/generic/plot.py

@@ -36,6 +36,12 @@
     try:
         from matplotlib.patches import PathPatch
         from matplotlib.path import Path
+
+        # Use matplotlib Agg backend (non-interactive) when the CI is running.
+        if os.getenv("ON_CI", "False") == "True":  # pragma: no cover
+            import matplotlib
+
+            matplotlib.use("Agg")
         import matplotlib.pyplot as plt
 
         rc_params = {

pyaedt/generic/touchstone_parser.py

@@ -8,6 +8,11 @@
 from pyaedt.misc.misc import installed_versions
 
 if not is_ironpython:
+    # Use matplotlib Agg backend (non-interactive) when the CI is running.
+    if os.getenv("ON_CI", "False") == "True":  # pragma: no cover
+        import matplotlib
+
+        matplotlib.use("Agg")
     import matplotlib.pyplot as plt
     import numpy as np
     import skrf as rf

pyaedt/modules/solutions.py

@@ -45,6 +45,11 @@
     except ImportError:
         pv = None
     try:
+        # Use matplotlib Agg backend (non-interactive) when the CI is running.
+        if os.getenv("ON_CI", "False") == "True":  # pragma: no cover
+            import matplotlib
+
+            matplotlib.use("Agg")
         import matplotlib.pyplot as plt
     except ImportError:
         plt = None