TST: correct webagg fallback behavior on headless machine

tacaswell · tacaswell · commit d03d736712e3 · 2019-10-27T21:46:52.000-04:00
diff --git a/lib/matplotlib/tests/test_backend_webagg.py b/lib/matplotlib/tests/test_backend_webagg.py
@@ -0,0 +1,16 @@
+import subprocess
+import sys
+import pytest
+
+
+@pytest.mark.parametrize('backend', ['webagg', 'nbagg'])
+def test_webagg_fallback(backend):
+    test_code = ("import matplotlib.pyplot as plt; " +
+                 "print(plt.get_backend());"
+                 f"assert '{backend}' == plt.get_backend().lower();")
+    ret = subprocess.call(
+        [sys.executable, "-c", test_code],
+        env={"MPLBACKEND": backend, "DISPLAY": ""}
+    )
+
+    assert ret == 0
