Add mock testing for XpressDirect/XpressPersistent.available()

pyomo/solvers/tests/checks/test_xpress_persistent.py

@@ -8,11 +8,16 @@
 #  rights in this software.
 #  This software is distributed under the 3-clause BSD License.
 #  ___________________________________________________________________________
+import logging
 
 import pyomo.common.unittest as unittest
 import pyomo.environ as pe
+import pyomo.solvers.plugins.solvers.xpress_direct as xpd
+
+from pyomo.common.log import LoggingIntercept
 from pyomo.core.expr.taylor_series import taylor_series_expansion
 from pyomo.opt.results.solver import TerminationCondition, SolverStatus
+from pyomo.solvers.plugins.solvers.xpress_persistent import XpressPersistent
 
 xpress_available = pe.SolverFactory('xpress_persistent').available(False)
 
@@ -330,3 +335,52 @@ def test_nonconvexqp_infeasible(self):
         self.assertEqual(
             results.solver.termination_condition, TerminationCondition.infeasible
         )
+
+    def test_available(self):
+        class mock_xpress(object):
+            def __init__(self, importable, initable):
+                self._initable = initable
+                xpd.xpress_available = importable
+
+            def log_import_warning(self, logger):
+                logging.getLogger(logger).warning("import warning")
+
+            def init(self):
+                if not self._initable:
+                    raise RuntimeError("init failed")
+
+            def free(self):
+                pass
+
+        orig = xpd.xpress, xpd.xpress_available
+        try:
+            _xpress_persistent = XpressPersistent
+            xpd.xpress = mock_xpress(True, True)
+            with LoggingIntercept() as LOG:
+                self.assertTrue(XpressPersistent().available(True))
+                self.assertTrue(XpressPersistent().available(False))
+            self.assertEqual(LOG.getvalue(), "")
+
+            xpd.xpress = mock_xpress(False, False)
+            with LoggingIntercept() as LOG:
+                self.assertFalse(XpressPersistent().available(False))
+            self.assertEqual(LOG.getvalue(), "")
+            with LoggingIntercept() as LOG:
+                with self.assertRaisesRegex(
+                    xpd.ApplicationError,
+                    "No Python bindings available for .*XpressPersistent.* "
+                    "solver plugin",
+                ):
+                    XpressPersistent().available(True)
+            self.assertEqual(LOG.getvalue(), "import warning\n")
+
+            xpd.xpress = mock_xpress(True, False)
+            with LoggingIntercept() as LOG:
+                self.assertFalse(XpressPersistent().available(False))
+            self.assertEqual(LOG.getvalue(), "")
+            with LoggingIntercept() as LOG:
+                with self.assertRaisesRegex(RuntimeError, "init failed"):
+                    XpressPersistent().available(True)
+            self.assertEqual(LOG.getvalue(), "")
+        finally:
+            xpd.xpress, xpd.xpress_available = orig