Make internal_solvers into a fixture

tests/__init__.py

@@ -1,3 +1,18 @@
 #  MIPLearn: Extensible Framework for Learning-Enhanced Mixed-Integer Optimization
 #  Copyright (C) 2020-2021, UChicago Argonne, LLC. All rights reserved.
 #  Released under the modified BSD license. See COPYING.md for more details.
+from typing import List
+
+import pytest
+
+from miplearn import InternalSolver, GurobiPyomoSolver, GurobiSolver
+from miplearn.solvers.pyomo.xpress import XpressPyomoSolver
+
+
+@pytest.fixture
+def internal_solvers() -> List[InternalSolver]:
+    return [
+        GurobiPyomoSolver(),
+        GurobiSolver(),
+        XpressPyomoSolver(),
+    ]

tests/solvers/__init__.py

@@ -3,15 +3,12 @@
 #  Released under the modified BSD license. See COPYING.md for more details.
 
 from inspect import isclass
-from typing import List, Callable, Any
+from typing import Any
 
 from miplearn.instance.base import Instance
 from miplearn.problems.knapsack import KnapsackInstance, GurobiKnapsackInstance
 from miplearn.solvers.gurobi import GurobiSolver
-from miplearn.solvers.internal import InternalSolver
 from miplearn.solvers.pyomo.base import BasePyomoSolver
-from miplearn.solvers.pyomo.gurobi import GurobiPyomoSolver
-from miplearn.solvers.pyomo.xpress import XpressPyomoSolver
 
 
 def _is_subclass_or_instance(obj: Any, parent_class: Any) -> bool:
@@ -34,11 +31,3 @@ def _get_knapsack_instance(solver: Any) -> Instance:
             capacity=67.0,
         )
     assert False
-
-
-def get_internal_solvers() -> List[InternalSolver]:
-    return [
-        GurobiPyomoSolver(),
-        GurobiSolver(),
-        XpressPyomoSolver(),
-    ]

tests/solvers/test_internal_solver.py

@@ -4,17 +4,19 @@
 
 import logging
 from io import StringIO
+from typing import List
 from warnings import warn
 
 import pyomo.environ as pe
 
+from miplearn import InternalSolver
 from miplearn.solvers import _RedirectOutput
 from miplearn.solvers.gurobi import GurobiSolver
 from miplearn.solvers.pyomo.base import BasePyomoSolver
-from . import (
+from . import _get_knapsack_instance
-    _get_knapsack_instance,
+
-    get_internal_solvers,
+# noinspection PyUnresolvedReferences
-)
+from .. import internal_solvers
 from ..fixtures.infeasible import get_infeasible_instance
 
 logger = logging.getLogger(__name__)
@@ -31,8 +33,10 @@ def test_redirect_output() -> None:
     assert io.getvalue() == "Hello world\n"
 
 
-def test_internal_solver_warm_starts() -> None:
+def test_internal_solver_warm_starts(
-    for solver in get_internal_solvers():
+    internal_solvers: List[InternalSolver],
+) -> None:
+    for solver in internal_solvers:
         logger.info("Solver: %s" % solver)
         instance = _get_knapsack_instance(solver)
         model = instance.to_model()
@@ -54,8 +58,10 @@ def test_internal_solver_warm_starts() -> None:
         assert stats["Upper bound"] == 725.0
 
 
-def test_internal_solver() -> None:
+def test_internal_solver(
-    for solver in get_internal_solvers():
+    internal_solvers: List[InternalSolver],
+) -> None:
+    for solver in internal_solvers:
         logger.info("Solver: %s" % solver)
 
         instance = _get_knapsack_instance(solver)
@@ -159,8 +165,10 @@ def test_internal_solver() -> None:
             assert round(solver.get_dual("eq_capacity")) == 0.0
 
 
-def test_relax() -> None:
+def test_relax(
-    for solver in get_internal_solvers():
+    internal_solvers: List[InternalSolver],
+) -> None:
+    for solver in internal_solvers:
         instance = _get_knapsack_instance(solver)
         solver.set_instance(instance)
         solver.relax()
@@ -169,8 +177,10 @@ def test_relax() -> None:
         assert round(stats["Lower bound"]) == 1288.0
 
 
-def test_infeasible_instance() -> None:
+def test_infeasible_instance(
-    for solver in get_internal_solvers():
+    internal_solvers: List[InternalSolver],
+) -> None:
+    for solver in internal_solvers:
         instance = get_infeasible_instance(solver)
         solver.set_instance(instance)
         mip_stats = solver.solve()
@@ -185,8 +195,10 @@ def test_infeasible_instance() -> None:
         assert lp_stats["LP value"] is None
 
 
-def test_iteration_cb() -> None:
+def test_iteration_cb(
-    for solver in get_internal_solvers():
+    internal_solvers: List[InternalSolver],
+) -> None:
+    for solver in internal_solvers:
         logger.info("Solver: %s" % solver)
         instance = _get_knapsack_instance(solver)
         solver.set_instance(instance)

tests/solvers/test_learning_solver.py

@@ -9,18 +9,23 @@ from typing import List, cast
 
 import dill
 
-from miplearn import Instance
+from miplearn import Instance, InternalSolver
 from miplearn.instance.picklegz import PickleGzInstance, write_pickle_gz, read_pickle_gz
 from miplearn.solvers.gurobi import GurobiSolver
 from miplearn.solvers.learning import LearningSolver
-from . import _get_knapsack_instance, get_internal_solvers
+from . import _get_knapsack_instance
+
+# noinspection PyUnresolvedReferences
+from tests import internal_solvers
 
 logger = logging.getLogger(__name__)
 
 
-def test_learning_solver() -> None:
+def test_learning_solver(
+    internal_solvers: List[InternalSolver],
+) -> None:
     for mode in ["exact", "heuristic"]:
-        for internal_solver in get_internal_solvers():
+        for internal_solver in internal_solvers:
             logger.info("Solver: %s" % internal_solver)
             instance = _get_knapsack_instance(internal_solver)
             solver = LearningSolver(
@@ -61,8 +66,10 @@ def test_learning_solver() -> None:
                 dill.dump(solver, file)
 
 
-def test_solve_without_lp() -> None:
+def test_solve_without_lp(
-    for internal_solver in get_internal_solvers():
+    internal_solvers: List[InternalSolver],
+) -> None:
+    for internal_solver in internal_solvers:
         logger.info("Solver: %s" % internal_solver)
         instance = _get_knapsack_instance(internal_solver)
         solver = LearningSolver(
@@ -74,8 +81,10 @@ def test_solve_without_lp() -> None:
         solver.solve(instance)
 
 
-def test_parallel_solve() -> None:
+def test_parallel_solve(
-    for internal_solver in get_internal_solvers():
+    internal_solvers: List[InternalSolver],
+) -> None:
+    for internal_solver in internal_solvers:
         instances = [_get_knapsack_instance(internal_solver) for _ in range(10)]
         solver = LearningSolver(solver=internal_solver)
         results = solver.parallel_solve(instances, n_jobs=3)
@@ -86,8 +95,10 @@ def test_parallel_solve() -> None:
             assert len(data.solution.keys()) == 4
 
 
-def test_solve_fit_from_disk() -> None:
+def test_solve_fit_from_disk(
-    for internal_solver in get_internal_solvers():
+    internal_solvers: List[InternalSolver],
+) -> None:
+    for internal_solver in internal_solvers:
         # Create instances and pickle them
         instances: List[Instance] = []
         for k in range(3):