Merge pull request #3482 from mrmundt/ipopt-bugfix

BUGFIX: Validator for `tee` in `contrib.solver`

Author: mrmundt

pyomo/contrib/solver/config.py

@@ -31,21 +31,45 @@
 
 
 def TextIO_or_Logger(val):
-    ans = []
-    if not isinstance(val, Sequence):
+    """
+    Validates and converts input into a list of valid output streams.
+
+    Accepts:
+      - sys.stdout
+      - Instances of io.TextIOBase
+      - logging.Logger (wrapped as LogStream)
+      - Boolean values (`True` -> sys.stdout)
+
+    Returns:
+      - A list of validated output streams.
+
+    Raises:
+      - ValueError if an invalid type is provided.
+    """
+    if isinstance(val, Sequence) and not isinstance(val, (str, bytes)):
+        val = list(val)
+
+    else:
         val = [val]
+
+    ans = []
+
     for v in val:
         if v.__class__ in native_logical_types:
             if v:
                 ans.append(sys.stdout)
-        elif isinstance(v, io.TextIOBase):
+        elif isinstance(v, (sys.stdout.__class__, io.TextIOBase)):
+            # We are guarding against file-like classes that do not derive from
+            # TextIOBase but are assigned to stdout / stderr.
+            # We still want to accept those classes.
             ans.append(v)
         elif isinstance(v, logging.Logger):
             ans.append(LogStream(level=logging.INFO, logger=v))
         else:
             raise ValueError(
-                f"Expected bool, TextIOBase, or Logger, but received {v.__class__}"
+                f"Expected sys.stdout, io.TextIOBase, Logger, or bool, but received {v.__class__}"
             )
+
     return ans
 
 

pyomo/contrib/solver/tests/unit/test_config.py

@@ -9,14 +9,52 @@
 #  This software is distributed under the 3-clause BSD License.
 #  ___________________________________________________________________________
 
+import logging
+import io
+
+import pyomo.environ as pyo
 from pyomo.common import unittest
+from pyomo.common.log import LogStream
+from pyomo.common.tee import capture_output
+from pyomo.common.dependencies import attempt_import
 from pyomo.contrib.solver.config import (
     SolverConfig,
     BranchAndBoundConfig,
     AutoUpdateConfig,
     PersistentSolverConfig,
+    TextIO_or_Logger,
 )
 
+ipopt, ipopt_available = attempt_import('ipopt')
+
+
+class TestTextIO_or_LoggerValidator(unittest.TestCase):
+    def test_booleans(self):
+        ans = TextIO_or_Logger(True)
+        self.assertTrue(isinstance(ans[0], io._io.TextIOWrapper))
+        ans = TextIO_or_Logger(False)
+        self.assertEqual(ans, [])
+
+    def test_logger(self):
+        logger = logging.getLogger('contrib.solver.config.test.1')
+        ans = TextIO_or_Logger(logger)
+        self.assertTrue(isinstance(ans[0], LogStream))
+
+    @unittest.skipIf(not ipopt_available, 'ipopt is not available')
+    def test_real_example(self):
+
+        m = pyo.ConcreteModel()
+        m.x = pyo.Var([1, 2], initialize=1, bounds=(0, None))
+        m.eq = pyo.Constraint(expr=m.x[1] * m.x[2] ** 1.5 == 3)
+        m.obj = pyo.Objective(expr=m.x[1] ** 2 + m.x[2] ** 2)
+
+        solver = pyo.SolverFactory("ipopt_v2")
+        with capture_output() as OUT:
+            solver.solve(m, tee=True, timelimit=5)
+
+        contents = OUT.getvalue()
+        self.assertIn('EXIT: Optimal Solution Found.', contents)
+
 
 class TestSolverConfig(unittest.TestCase):
     def test_interface_default_instantiation(self):