Update guard for pint import to possibly avoid recursion error on FreeBSD

Author: jsiirola

pyomo/contrib/viewer/tests/test_data_model_item.py

@@ -46,15 +46,10 @@
 from pyomo.contrib.viewer.model_browser import ComponentDataItem
 from pyomo.contrib.viewer.ui_data import UIData
 from pyomo.common.dependencies import DeferredImportError
+from pyomo.core.base.units_container import pint_available
 
-try:
-    x = pyo.units.m
-    units_available = True
-except DeferredImportError:
-    units_available = False
 
-
-@unittest.skipIf(not units_available, "Pyomo units are not available")
+@unittest.skipIf(not pint_available, "Pyomo units are not available")
 class TestDataModelItem(unittest.TestCase):
     def setUp(self):
         # Borrowed this test model from the trust region tests

pyomo/contrib/viewer/tests/test_data_model_tree.py

@@ -42,12 +42,7 @@
 from pyomo.contrib.viewer.model_browser import ComponentDataModel
 import pyomo.contrib.viewer.qt as myqt
 from pyomo.common.dependencies import DeferredImportError
-
-try:
-    _x = pyo.units.m
-    units_available = True
-except DeferredImportError:
-    units_available = False
+from pyomo.core.base.units_container import pint_available
 
 available = myqt.available
 
@@ -63,7 +58,7 @@ def __init__(*args, **kwargs):
             pass
 
 
-@unittest.skipIf(not available or not units_available, "PyQt or units not available")
+@unittest.skipIf(not available or not pint_available, "PyQt or units not available")
 class TestDataModel(unittest.TestCase):
     def setUp(self):
         # Borrowed this test model from the trust region tests