From e7426e445a9bf8bd1110bb75602d9c10e6a5d906 Mon Sep 17 00:00:00 2001
From: "Alinson S. Xavier" <git@axavier.org>
Date: Thu, 3 Dec 2020 12:00:32 -0600
Subject: [PATCH] Make tests compatible with Python 3.7+

---
 .github/workflows/test.yml         |  4 ++--
 Makefile                           |  7 +++++--
 miplearn/solvers/tests/__init__.py | 10 ++++++++--
 3 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 80c757a..99c99d1 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -5,7 +5,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: [3.6, 3.7, 3.8]
+        python-version: [3.6, 3.7, 3.8, 3.9]
 
     steps:
     - name: Check out source code
@@ -24,4 +24,4 @@ jobs:
 
     - name: Test with pytest
       run: |
-        pytest
\ No newline at end of file
+        pytest
diff --git a/Makefile b/Makefile
index b31d525..376f6ff 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,6 @@
 PYTHON      := python3
 PYTEST      := pytest
-PIP         := pip3
+PIP         := $(PYTHON) -m pip
 PYTEST_ARGS := -W ignore::DeprecationWarning -vv -x --log-level=DEBUG
 VERSION     := 0.2
 
@@ -24,8 +24,11 @@ docs:
 docs-dev:
 	mkdocs build -d ../docs/dev/
 
-install:
+install-deps:
+	$(PIP) install -i https://pypi.gurobi.com gurobipy
 	$(PIP) install -r requirements.txt
+
+install:
 	$(PYTHON) setup.py install
 
 uninstall:
diff --git a/miplearn/solvers/tests/__init__.py b/miplearn/solvers/tests/__init__.py
index 74b35bc..b7e3e61 100644
--- a/miplearn/solvers/tests/__init__.py
+++ b/miplearn/solvers/tests/__init__.py
@@ -2,23 +2,29 @@
 #  Copyright (C) 2020, UChicago Argonne, LLC. All rights reserved.
 #  Released under the modified BSD license. See COPYING.md for more details.
 
+from inspect import isclass
 from miplearn import BasePyomoSolver, GurobiSolver, GurobiPyomoSolver
 from miplearn.problems.knapsack import KnapsackInstance, GurobiKnapsackInstance
 
 
 def _get_instance(solver):
-    if issubclass(solver, BasePyomoSolver) or isinstance(solver, BasePyomoSolver):
+    def _is_subclass_or_instance(solver, parentClass):
+        return isinstance(solver, parentClass) or (isclass(solver) and issubclass(solver, parentClass))
+
+    if _is_subclass_or_instance(solver, BasePyomoSolver):
         return KnapsackInstance(
             weights=[23., 26., 20., 18.],
             prices=[505., 352., 458., 220.],
             capacity=67.,
         )
-    if issubclass(solver, GurobiSolver) or isinstance(solver, GurobiSolver):
+
+    if _is_subclass_or_instance(solver, GurobiSolver):
         return GurobiKnapsackInstance(
             weights=[23., 26., 20., 18.],
             prices=[505., 352., 458., 220.],
             capacity=67.,
         )
+
     assert False