Add checks for programs which are required for the test suite to run.

All prerequisite programs are checked for existance, and if any are
missing,
a list of missing programs is printed, and the test suite is aborted.
All programs currently used in the tests, except those in core-utils,
are checked.

tests/run-tests

@@ -1,124 +1,145 b''
 #!/bin/sh -e
 
 LANG="C"; export LANG
 LC_CTYPE="C"; export LC_CTYPE
 LC_NUMERIC="C"; export LC_NUMERIC
 LC_TIME="C"; export LC_TIME
 LC_COLLATE="C"; export LC_COLLATE
 LC_MONETARY="C"; export LC_MONETARY
 LC_MESSAGES="C"; export LC_MESSAGES
 LC_PAPER="C"; export LC_PAPER
 LC_NAME="C"; export LC_NAME
 LC_ADDRESS="C"; export LC_ADDRESS
 LC_TELEPHONE="C"; export LC_TELEPHONE
 LC_MEASUREMENT="C"; export LC_MEASUREMENT
 LC_IDENTIFICATION="C"; export LC_IDENTIFICATION
 LC_ALL=""; export LC_ALL
 TZ=GMT; export TZ
 HGEDITOR=true; export HGEDITOR
 HGMERGE=true; export HGMERGE
 HGUSER="test"; export HGUSER
 
 umask 022
 
 tests=0
 failed=0
 
 HGTMP=""
 cleanup_exit() {
     rm -rf "$HGTMP"
 }
 
 # Remove temporary files even if we get interrupted
 trap "cleanup_exit" 0 # normal exit
 trap "exit 255" 1 2 3 6 15 # HUP INT QUIT ABRT TERM
 
 HGTMP="${TMPDIR-/tmp}/hgtests.$RANDOM.$RANDOM.$RANDOM.$$"
 (umask 077 && mkdir "$HGTMP") || {
     echo "Could not create temporary directory! Exiting." 1>&2
     exit 1
 }
 
 TESTDIR="$PWD"
 
 if [ -d /usr/lib64 ]; then
     lib=lib64
 else
     lib=lib
 fi
 
 INST="$HGTMP/install"
 cd ..
 if ${PYTHON-python} setup.py install --home="$INST" > tests/install.err 2>&1
 then
     rm tests/install.err
 else
     cat tests/install.err
     exit 1
 fi
 cd "$TESTDIR"
 
 PATH="$INST/bin:$PATH"; export PATH
 PYTHONPATH="$INST/$lib/python"; export PYTHONPATH
 
 
 run_one() {
     rm -f "$1.err"
 
     mkdir "$HGTMP/$1"
     cd "$HGTMP/$1"
     fail=0
     HOME="$HGTMP/$1"; export HOME
     OUT="$HGTMP/$1.out"
     OUTOK="$TESTDIR/$1.out"
     ERR="$TESTDIR/$1.err"
 
     if "$TESTDIR/$1" > "$OUT" 2>&1; then
 	: no error
     else
 	echo "$1 failed with error code $?"
 	fail=1
     fi
 
     if [ -s "$OUT" -a ! -s "$OUTOK" ] ; then
 	cp "$OUT" "$ERR"
 	echo
 	echo "$1 generated unexpected output:"
 	cat "$ERR"
 	fail=1
     elif [ -r "$OUTOK" ]; then
 	if diff -u "$OUTOK" "$OUT" > /dev/null; then
 	    : no differences
 	else
 	    cp "$OUT" "$ERR"
 	    echo
 	    echo "$1 output changed:"
 	    diff -u "$OUTOK" "$ERR" || true
 	    fail=1
 	fi
     fi
 
     cd "$TESTDIR"
     rm -f "$HGTMP/$1.out"
     rm -rf "$HGTMP/$1"
     return $fail
 }
 
+# list of prerequisite programs 
+# stuff from coreutils (cat, rm, etc) are not tested
+prereqs="python merge diff grep unzip md5sum gunzip sed"
+missing=''
+for pre in $prereqs ; do
+    if type $pre > /dev/null 2>&1 ; then
+        : prereq exists
+    else 
+        missing="$pre $missing"
+    fi
+done
+
+if [ "$missing" != ''  ] ; then
+    echo "ERROR: the test suite needs some programs to execute correctly."
+    echo "The following programs are missing: "
+    for pre in $missing; do
+        echo "   $pre"
+    done
+    exit 1
+fi
+
 TESTS="$*"
 if [ -z "$TESTS" ] ; then
     TESTS=`ls test-* | grep -v "[.~]"`
 fi
 
 for f in $TESTS ; do
     echo -n "."
     run_one $f || failed=`expr $failed + 1`
     tests=`expr $tests + 1`
 done
 
 echo
 echo "Ran $tests tests, $failed failed."
 
 if [ $failed -gt 0 ] ; then
     exit 1
 fi
 exit 0