Merge pull request Pyomo#2913 from jsiirola/gams-pickle

GAMS: fix pickling models, update tests

.github/workflows/test_branches.yml

@@ -445,6 +445,8 @@ jobs:
         echo "DYLD_LIBRARY_PATH=${env:DYLD_LIBRARY_PATH}:$GAMS_DIR" `
             Out-File -FilePath $env:GITHUB_ENV -Encoding utf8 -Append
         $INSTALLER = "${env:DOWNLOAD_DIR}/gams_install.exe"
+        # We are pinning to 29.1.0 because a license is required for
+        # versions after this in order to run in demo mode.
         $URL = "https://d37drm4t2jghv5.cloudfront.net/distributions/29.1.0"
         if ( "${{matrix.TARGET}}" -eq "win" ) {
             $URL = "$URL/windows/windows_x64_64.exe"

.github/workflows/test_pr_and_main.yml

@@ -463,6 +463,8 @@ jobs:
         echo "DYLD_LIBRARY_PATH=${env:DYLD_LIBRARY_PATH}:$GAMS_DIR" `
             Out-File -FilePath $env:GITHUB_ENV -Encoding utf8 -Append
         $INSTALLER = "${env:DOWNLOAD_DIR}/gams_install.exe"
+        # We are pinning to 29.1.0 because a license is required for
+        # versions after this in order to run in demo mode.
         $URL = "https://d37drm4t2jghv5.cloudfront.net/distributions/29.1.0"
         if ( "${{matrix.TARGET}}" -eq "win" ) {
             $URL = "$URL/windows/windows_x64_64.exe"

pyomo/repn/plugins/gams_writer.py

@@ -308,6 +308,27 @@ def split_long_line(line):
     return new_lines
 
 
+class GAMSSymbolMap(SymbolMap):
+    def __init__(self, var_labeler, var_list):
+        super().__init__(self.var_label)
+        self.var_labeler = var_labeler
+        self.var_list = var_list
+
+    def var_label(self, obj):
+        # if obj.is_fixed():
+        #    return str(value(obj))
+        return self.getSymbol(obj, self.var_recorder)
+
+    def var_recorder(self, obj):
+        ans = self.var_labeler(obj)
+        try:
+            if obj.is_variable_type():
+                self.var_list.append(ans)
+        except:
+            pass
+        return ans
+
+
 @WriterFactory.register('gams', 'Generate the corresponding GAMS file')
 class ProblemWriter_gams(AbstractProblemWriter):
     def __init__(self):
@@ -492,21 +513,7 @@ def __call__(self, model, output_filename, solver_capability, io_options):
 
         var_list = []
 
-        def var_recorder(obj):
-            ans = var_labeler(obj)
-            try:
-                if obj.is_variable_type():
-                    var_list.append(ans)
-            except:
-                pass
-            return ans
-
-        def var_label(obj):
-            # if obj.is_fixed():
-            #    return str(value(obj))
-            return symbolMap.getSymbol(obj, var_recorder)
-
-        symbolMap = SymbolMap(var_label)
+        symbolMap = GAMSSymbolMap(var_labeler, var_list)
 
         # when sorting, there are a non-trivial number of
         # temporary objects created. these all yield
@@ -527,7 +534,7 @@ def var_label(obj):
                     output_file=output_file,
                     solver_capability=solver_capability,
                     var_list=var_list,
-                    var_label=var_label,
+                    var_label=symbolMap.var_label,
                     symbolMap=symbolMap,
                     con_labeler=con_labeler,
                     sort=sort,

pyomo/solvers/tests/checks/test_pickle.py

@@ -169,7 +169,15 @@ def return_test(self):
 for key, value in generate_scenarios(lambda c: c.test_pickling):
     model, solver, io = key
     cls = driver[model]
-
+    # July 19, 2023: There is an issue with certain GAMS cases that is
+    # causing failures. This is not universal, however, so we cannot add
+    # the cases directly to testcases.py.
+    if (
+        (solver == 'gams')
+        and (io in ['gms', 'python'])
+        and ('.LP_simple_kernel' in str(value.model))
+    ):
+        value.status = 'expected failure'
     # Symbolic labels
     test_name = "test_" + solver + "_" + io + "_symbolic_labels"
     test_method = create_method(model, solver, io, value, True)

pyomo/solvers/tests/solvers.py

@@ -9,7 +9,7 @@
 #  This software is distributed under the 3-clause BSD License.
 #  ___________________________________________________________________________
 
-__all__ = ['test_solver_cases', 'available_solvers']
+__all__ = ['test_solver_cases']
 
 import logging
 

pyomo/solvers/tests/testcases.py

@@ -108,6 +108,26 @@
 # NO EXPECTED FAILURES
 #
 
+#
+# GAMS
+#
+
+ExpectedFailures['gams', 'gms', 'MILP_unbounded'] = (
+    lambda v: v <= _trunk_version,
+    "GAMS requires finite bounds for integer variables. 1.0E100 is as extreme"
+    "as GAMS will define, and should be enough to appear unbounded. If the"
+    "solver cannot handle this bound, explicitly set a smaller bound on"
+    "the pyomo model, or try a different GAMS solver.",
+)
+
+ExpectedFailures['gams', 'python', 'MILP_unbounded'] = (
+    lambda v: v <= _trunk_version,
+    "GAMS requires finite bounds for integer variables. 1.0E100 is as extreme"
+    "as GAMS will define, and should be enough to appear unbounded. If the"
+    "solver cannot handle this bound, explicitly set a smaller bound on"
+    "the pyomo model, or try a different GAMS solver.",
+)
+
 #
 # GLPK
 #
@@ -261,83 +281,6 @@
         'BARON 22.1.19 reports model as optimal',
     )
 
-#
-# The following were necessary before we started adding the 'WantDual'
-# option when a user explicitly defines a 'dual' or 'rc' suffix to
-# "force" Baron to run a local solve (if necessary) and always return
-# dual nformation.
-#
-
-# # Known to fail through 18.11.15, but was resolved by 19.12.7
-# ExpectedFailures['baron', 'bar', 'MILP_unbounded'] = (
-#     lambda v: v <= (18,11,15),
-#     ['dual'],
-#     "Baron fails to report a MILP model as unbounded")
-
-# # Known to work through 18.11.15, and fail in 19.12.7
-# MissingSuffixFailures['baron', 'bar', 'LP_piecewise'] = (
-#     lambda v: v <= (15,0,0,0) or v > (18,11,15),
-#     ['dual'],
-#     "Baron will not return dual solution when a solution is "
-#     "found during preprocessing.")
-
-# # Marking this test suffixes as fragile: Baron 20.4.14 will
-# # intermittently return suffixes.
-# MissingSuffixFailures['baron', 'bar', 'QP_simple'] = (
-#     lambda v: v <= (15,2,0,0) or v > (18,11,15),
-#     {'dual': (False, {}), 'rc': (False, {})},
-#     "Baron will intermittently return dual solution when "
-#     "a solution is found during preprocessing.")
-
-# # Known to fail through 17.4.1, but was resolved by 18.5.9
-# MissingSuffixFailures['baron', 'bar', 'QCP_simple'] = (
-#     lambda v: v <= (17,4,1) or v > (18,11,15),
-#     ['dual','rc'],
-#     "Baron will not return dual solution when a solution is "
-#     "found during preprocessing.")
-
-# # Known to work through 18.11.15, and fail in 19.12.7
-# MissingSuffixFailures['baron', 'bar', 'LP_block'] = (
-#     lambda v: v > (18,11,15),
-#     ['dual'],
-#     "Baron will not return dual solution when a solution is "
-#     "found during preprocessing.")
-
-# # Known to work through 18.11.15, and fail in 19.12.7
-# MissingSuffixFailures['baron', 'bar', 'LP_inactive_index'] = (
-#     lambda v: v > (18,11,15),
-#     ['dual'],
-#     "Baron will not return dual solution when a solution is "
-#     "found during preprocessing.")
-
-# # Known to work through 18.11.15, and fail in 19.12.7
-# MissingSuffixFailures['baron', 'bar', 'LP_simple'] = (
-#     lambda v: v > (18,11,15),
-#     ['dual'],
-#     "Baron will not return dual solution when a solution is "
-#     "found during preprocessing.")
-
-# # Known to work through 18.11.15, and fail in 19.12.7
-# MissingSuffixFailures['baron', 'bar', 'LP_trivial_constraints'] = (
-#     lambda v: v > (18,11,15),
-#     ['dual'],
-#     "Baron will not return dual solution when a solution is "
-#     "found during preprocessing.")
-
-# # Known to work through 19.12.7, and fail in 20.4.14
-# MissingSuffixFailures['baron', 'bar', 'LP_duals_minimize'] = (
-#     lambda v: v > (19,12,7),
-#     ['dual','rc'],
-#     "Baron will not return dual solution when a solution is "
-#     "found during preprocessing.")
-
-# # Known to work through 19.12.7, and fail in 20.4.14
-# MissingSuffixFailures['baron', 'bar', 'LP_duals_maximize'] = (
-#     lambda v: v > (19,12,7),
-#     ['dual','rc'],
-#     "Baron will not return dual solution when a solution is "
-#     "found during preprocessing.")
-
 
 #
 # KNITROAMPL