sanity: ensure that all environment variables are documented

* tests/sanity/getenv.test: New file.
* tests/Makefile.am: Add it.
* bin/man/spot-x.x: Document SPOT_STUTTER_CHECK and SPOT_DEBUG_PARSER.

bin/man/spot-x.x

@@ -65,6 +65,11 @@ is the same as running
 but the use of the environment variable makes more sense if you set
 it up once for many commands.
 
+.TP
+\fBSPOT_DEBUG_PARSER\fR
+If this variable is set to any value, the automaton parser of Spot is
+executed in debug mode, showing how the input is processed.
+
 .TP
 \fBSPOT_DOTDEFAULT\fR
 Whenever the \f(CW--dot\fR option is used without argument (even
@@ -129,6 +134,31 @@ all Streett automata, however we do not recommand setting it to less
 than 2, because the "Fin-removal" approach is better for single-pair
 Streett automata.
 
+.TP
+\fBSPOT_STUTTER_CHECK\fR
+Select the default check used to decide stutter invariance.  The
+variable should hold a value between 1 and 8, corresponding to the
+following tests described in our Spin'15 paper (see the BIBLIOGRAPHY
+section).  The default is 8.
+.RS
+.IP 1
+sl(a) x sl(!a)
+.IP 2
+sl(cl(a)) x !a
+.IP 3
+cl(sl(a)) x !a
+.IP 4
+sl2(a) x sl2(!a)
+.IP 5
+sl2(cl(a)) x !a
+.IP 6
+cl(sl2(a)) x !a
+.IP 7
+sl(a) x sl(!a), performed on-the-fly
+.IP 8
+cl(a) x cl(!a)
+.RE
+
 .TP
 \fBSPOT_TMPDIR\fR, \fBTMPDIR\fR
 These variables control in which directory temporary files (e.g.,
@@ -182,6 +212,15 @@ SAT Solving.  Proceedings of SAT'10.  LNCS 6175.
 Our SAT-based minimization procedures are generalizations of this
 paper to deal with TBA or TGBA.
 
+.TP
+4.
+Thibaud Michaud and Alexandre Duret-Lutz: Practical stutter-invariance
+checks for ω-regular languages, Proceedings of SPIN'15.  LNCS 9232.
+
+Describes the stutter-invariance checks that can be selected through
+\fBSPOT_STUTTER_CHECK\fR.
+
+
 [SEE ALSO]
 .BR ltl2tgba (1)
 .BR ltl2tgta (1)

tests/Makefile.am

@@ -418,6 +418,7 @@ endif
 TESTS_sanity = \
   sanity/80columns.test \
   sanity/bin.test \
+  sanity/getenv.test \
   sanity/includes.test \
   sanity/ipynb.pl \
   sanity/namedprop.test \

tests/sanity/getenv.test

@@ -0,0 +1,51 @@
+#! /bin/sh
+# -*- 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/>.
+
+
+# We used to loop over more directories before the source tree was
+# rearranged.  So there is only one left today, but we keep the loop
+# in case we want to add more in the future.
+
+set +x
+
+DOC=bin/man/spot-x.x
+
+rm -f getenv.log
+
+TOP=${srcdir-.}/../..
+for dir in "$TOP/spot" "$TOP/bin"; do
+  find "$dir" \(    -name "${1-*}.hh" \
+                 -o -name "${1-*}.hxx" \
+                 -o -name "${1-*}.cc" \) \
+                 -a -not -path '*.dir/*' \
+                 -a -type f -a -print
+done |
+xargs sed -n 's/.*getenv("\([^"]*\)").*/\1/p' |
+sort | uniq |
+while read prop; do
+   if ! grep -q "$prop" "$TOP/$DOC"; then
+     echo "* $prop" >>getenv.log
+   fi
+done
+if test -f getenv.log; then
+  echo "These environment variables are not documented in $DOC:"
+  cat getenv.log
+  exit 1
+fi