Add a test to check multiprocessing support

pygmt/tests/test_session_management.py

@@ -2,6 +2,7 @@
 Test the session management modules.
 """
 import os
+from pathlib import Path
 
 import pytest
 from pygmt.clib import Session
@@ -57,3 +58,35 @@ def test_gmt_compat_6_is_applied(capsys):
  # Make sure no global "gmt.conf" in the current directory
  assert not os.path.exists("gmt.conf")
  begin() # Restart the global session
+
+
+def gmt_func(figname):
+ """
+ Workaround to let PyGMT support multiprocessing.
+
+ See
+ https://github.com/GenericMappingTools/pygmt/issues/217#issuecomment-754774875
+ """
+ from importlib import reload
+
+ import pygmt
+
+ reload(pygmt)
+ fig = pygmt.Figure()
+ fig.basemap(region=[10, 70, -3, 8], projection="X8c/6c", frame="afg")
+ fig.savefig(figname)
+
+
+def test_session_multiprocessing():
+ """
+ Make sure that the multiprocessing is supported if pygmt is re-imported.
+ """
+
+ import multiprocessing as mp
+
+ fig_prefix = "test_session_multiprocessing"
+ with mp.Pool(2) as p:
+ p.map(gmt_func, [f"{fig_prefix}-1.png", f"{fig_prefix}-2.png"])
+ for i in [1, 2]:
+ assert Path(f"{fig_prefix}-{i}.png").exists()
+ Path(f"{fig_prefix}-{i}.png").unlink()