Disable some tests that HiGHS can not pass.

Some tests can't be used because HiGHS doesn't support some required feature, eg
cut generation, lazy constraints or MIP start. This affects many of the
examples (so we exclude all now) and also the tests "rcpsp" and "two_dim_pack".

Some others fail because the current version of HiGHS doesn't allow querying the
variable type. So we have to keep track of that in the wrapper, which only works
when the model is built in Python, but not when read from a file, ie in the
tests "mip_files".

Finally, some examples yielded a parse error, eg "1443_0-9.lp".

Was: Revert "include HiGHS as solvers in other (slow) tests". This (partially)
reverts commit 8918708.

Author: rschwarz

test/examples_test.py

@@ -8,16 +8,12 @@
 import importlib.machinery
 import pytest
 
-import mip.highs
-
 
 EXAMPLES = glob(join("..", "examples", "*.py")) + glob(join(".", "examples", "*.py"))
 
 SOLVERS = ["cbc"]
 if "GUROBI_HOME" in environ:
     SOLVERS += ["gurobi"]
-if mip.highs.has_highs:
-    SOLVERS += ["HiGHS"]
 
 
 @pytest.mark.parametrize("solver, example", product(SOLVERS, EXAMPLES))

test/mip_files_test.py

@@ -7,8 +7,7 @@
 from itertools import product
 import pytest
 import mip
-import mip.highs
-from mip import Model, OptimizationStatus, GUROBI, CBC, HIGHS
+from mip import Model, OptimizationStatus, GUROBI, CBC
 
 # for each MIP in test/data, best lower and upper bounds
 # to be used when checking optimization results
@@ -90,8 +89,6 @@
 SOLVERS = [CBC]
 if "GUROBI_HOME" in environ:
     SOLVERS += [GUROBI]
-if mip.highs.has_highs:
-    SOLVERS += [HIGHS]
 
 # check availability of test data
 DATA_DIR = join(join(dirname(mip.__file__)[0:-3], "test"), "data")

test/mip_test.py

@@ -383,7 +383,9 @@ def test_tsp_cuts(solver: str):
     assert abs(m.objective_value - 262) <= TOL  # "mip model objective"
 
 
-@pytest.mark.parametrize("solver", SOLVERS)
+# Exclude HiGHS solver, which doesn't support MIP start.
+SOLVERS_WITH_MIPSTART = [s for s in SOLVERS if s != HIGHS]
+@pytest.mark.parametrize("solver", SOLVERS_WITH_MIPSTART)
 def test_tsp_mipstart(solver: str):
     """tsp related tests"""
     N = ["a", "b", "c", "d", "e", "f", "g"]

test/rcpsp_test.py

@@ -5,8 +5,7 @@
 import json
 from itertools import product
 import pytest
-import mip.highs
-from mip import CBC, GUROBI, HIGHS, OptimizationStatus
+from mip import CBC, GUROBI, OptimizationStatus
 from mip_rcpsp import create_mip
 
 INSTS = glob("./data/rcpsp*.json") + glob("./test/data/rcpsp*.json")
@@ -16,8 +15,6 @@
 SOLVERS = [CBC]
 if "GUROBI_HOME" in environ:
     SOLVERS += [GUROBI]
-if mip.highs.has_highs:
-    SOLVERS += [HIGHS]
 
 
 @pytest.mark.parametrize("solver, instance", product(SOLVERS, INSTS))

test/two_dim_pack_test.py

@@ -5,8 +5,7 @@
 import json
 from itertools import product
 import pytest
-import mip.highs
-from mip import CBC, GUROBI, HIGHS, OptimizationStatus
+from mip import CBC, GUROBI, OptimizationStatus
 from mip_2d_pack import create_mip
 
 INSTS = glob("./data/two_dim_pack_p*.json") + glob(
@@ -18,8 +17,6 @@
 SOLVERS = [CBC]
 if "GUROBI_HOME" in environ:
     SOLVERS += [GUROBI]
-if mip.highs.has_highs:
-    SOLVERS += [HIGHS]
 
 
 @pytest.mark.parametrize("solver, instance", product(SOLVERS, INSTS))