emptiness checks: replace assert-preconditions by exceptions

* spot/twaalgos/couvreurnew.cc, spot/twaalgos/gv04.cc,
spot/twaalgos/magic.cc, spot/twaalgos/se05.cc, spot/twaalgos/tau03.cc,
spot/twaalgos/tau03opt.cc: Throw if precondition on acceptance
condition is not satisfied.
* tests/python/misc-ec.py: New file.
* tests/Makefile.am: Add it.
* NEWS: Mention the change.

tests/python/misc-ec.py

@@ -0,0 +1,47 @@
+# -*- mode: python; coding: utf-8 -*-
+# Copyright (C) 2017 Laboratoire de Recherche et Développement de l'Epita
+# (LRDE).
+#
+# This file is part of Spot, a model checking library.
+#
+# Spot is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# Spot is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+# or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
+# License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import spot
+aut = spot.translate("G(p0 | (p0 R Xp0) | XF(!p0 & p1))", 'BA')
+ec = spot.make_emptiness_check_instantiator('SE05')[0].instantiate(aut)
+n = 0
+while True:
+    res = ec.check()
+    if not res:
+        break
+    print(res.accepting_run())
+    n += 1
+assert n == 2
+
+for name in ['SE05', 'CVWY90', 'GV04']:
+    aut = spot.translate("GFa && GFb")
+    try:
+        ec = spot.make_emptiness_check_instantiator(name)[0].instantiate(aut)
+        print(ec.check().accepting_run())
+    except RuntimeError as e:
+        assert "Büchi or weak" in str(e)
+
+aut = spot.translate("a", 'monitor')
+try:
+    ec = spot.make_emptiness_check_instantiator('Tau03')[0].instantiate(aut)
+except RuntimeError as e:
+    assert "at least one" in str(e)
+
+aut = spot.translate("a", 'ba')
+ec = spot.make_emptiness_check_instantiator('Tau03')[0].instantiate(aut)