update tests

Author: tomvanmele

tests/compas/datastructures/test_network.py

@@ -1,6 +1,5 @@
 import pytest
 
-import compas
 from compas.datastructures import Network
 
 
@@ -33,15 +32,19 @@ def test_add_node():
 
 
 def test_non_planar(k5_network):
-    if compas.IPY:
+    try:
+        import planarity  # noqa: F401
+    except ImportError:
         return
 
     from compas.datastructures import network_is_planar
     assert network_is_planar(k5_network) is not True
 
 
 def test_planar(k5_network):
-    if compas.IPY:
+    try:
+        import planarity  # noqa: F401
+    except ImportError:
         return
 
     from compas.datastructures import network_is_planar