Python api unit tests for Result (#6763)

This PR translates the cpp API unit tests about results to python.
The original cpp file is: https://github.com/cvc5/cvc5/blob/master/test/unit/api/result_black.cpp

The translation made rise to one addition to the python API:
The UnknownExplanation object from the cpp API was represented by a string in the python API.
Now we have a more faithful representation, as an enum.

2 files changed, 116 insertions, 0 deletions

diff --git a/test/python/CMakeLists.txt b/test/python/CMakeLists.txt
index 54134b510..cefc16a07 100644
--- a/test/python/CMakeLists.txt
+++ b/test/python/CMakeLists.txt
@@ -33,3 +33,4 @@ cvc5_add_python_api_test(pytest_term unit/api/test_term.py)
 cvc5_add_python_api_test(pytest_datatype_api unit/api/test_datatype_api.py)
 cvc5_add_python_api_test(pytest_grammar unit/api/test_grammar.py)
 cvc5_add_python_api_test(pytest_to_python_obj unit/api/test_to_python_obj.py)
+cvc5_add_python_api_test(pytest_result unit/api/test_result.py)
diff --git a/test/python/unit/api/test_result.py b/test/python/unit/api/test_result.py
new file mode 100644
index 000000000..bd97646f9
--- /dev/null
+++ b/test/python/unit/api/test_result.py
@@ -0,0 +1,115 @@
+###############################################################################
+# Top contributors (to current version):
+#   Yoni Zohar
+#
+# This file is part of the cvc5 project.
+#
+# Copyright (c) 2009-2021 by the authors listed in the file AUTHORS
+# in the top-level source directory and their institutional affiliations.
+# All rights reserved.  See the file COPYING in the top-level source
+# directory for licensing information.
+# #############################################################################
+#
+# Unit tests for result API.
+#
+# Obtained by translating test/unit/api/result_black.cpp
+##
+
+import pytest
+import pycvc5
+from pycvc5 import kinds
+from pycvc5 import Result
+from pycvc5 import UnknownExplanation
+
+
+@pytest.fixture
+def solver():
+    return pycvc5.Solver()
+
+
+def test_is_null(solver):
+    res_null = Result(solver)
+    assert res_null.isNull()
+    assert not res_null.isSat()
+    assert not res_null.isUnsat()
+    assert not res_null.isSatUnknown()
+    assert not res_null.isEntailed()
+    assert not res_null.isNotEntailed()
+    assert not res_null.isEntailmentUnknown()
+    u_sort = solver.mkUninterpretedSort("u")
+    x = solver.mkVar(u_sort, "x")
+    solver.assertFormula(x.eqTerm(x))
+    res = solver.checkSat()
+    assert not res.isNull()
+
+
+def test_eq(solver):
+    u_sort = solver.mkUninterpretedSort("u")
+    x = solver.mkVar(u_sort, "x")
+    solver.assertFormula(x.eqTerm(x))
+    res2 = solver.checkSat()
+    res3 = solver.checkSat()
+    res = res2
+    assert res == res2
+    assert res3 == res2
+
+
+def test_is_sat(solver):
+    u_sort = solver.mkUninterpretedSort("u")
+    x = solver.mkVar(u_sort, "x")
+    solver.assertFormula(x.eqTerm(x))
+    res = solver.checkSat()
+    assert res.isSat()
+    assert not res.isSatUnknown()
+
+
+def test_is_unsat(solver):
+    u_sort = solver.mkUninterpretedSort("u")
+    x = solver.mkVar(u_sort, "x")
+    solver.assertFormula(x.eqTerm(x).notTerm())
+    res = solver.checkSat()
+    assert res.isUnsat()
+    assert not res.isSatUnknown()
+
+
+def test_is_sat_unknown(solver):
+    solver.setLogic("QF_NIA")
+    solver.setOption("incremental", "false")
+    solver.setOption("solve-int-as-bv", "32")
+    int_sort = solver.getIntegerSort()
+    x = solver.mkVar(int_sort, "x")
+    solver.assertFormula(x.eqTerm(x).notTerm())
+    res = solver.checkSat()
+    assert not res.isSat()
+    assert res.isSatUnknown()
+
+
+def test_is_entailed(solver):
+    solver.setOption("incremental", "true")
+    u_sort = solver.mkUninterpretedSort("u")
+    x = solver.mkConst(u_sort, "x")
+    y = solver.mkConst(u_sort, "y")
+    a = x.eqTerm(y).notTerm()
+    b = x.eqTerm(y)
+    solver.assertFormula(a)
+    entailed = solver.checkEntailed(a)
+    assert entailed.isEntailed()
+    assert not entailed.isEntailmentUnknown()
+    not_entailed = solver.checkEntailed(b)
+    assert not_entailed.isNotEntailed()
+    assert not not_entailed.isEntailmentUnknown()
+
+
+def test_is_entailment_unknown(solver):
+    solver.setLogic("QF_NIA")
+    solver.setOption("incremental", "false")
+    solver.setOption("solve-int-as-bv", "32")
+    int_sort = solver.getIntegerSort()
+    x = solver.mkVar(int_sort, "x")
+    solver.assertFormula(x.eqTerm(x).notTerm())
+    res = solver.checkEntailed(x.eqTerm(x))
+    assert not res.isEntailed()
+    assert res.isEntailmentUnknown()
+    print(type(pycvc5.RoundTowardZero))
+    print(type(pycvc5.UnknownReason))
+    assert res.getUnknownExplanation() == pycvc5.UnknownReason