Streamline reduce_tests.sh a bit

Swaps from multidelta that makes things more difficult without giving any new features to singledelta

Adds a stub showing how to test for a target output string instead of test success

Author: kevingranade

tools/reduce_tests.sh

@@ -1,21 +1,20 @@
 #!/bin/bash
 
-# A helper script to use multidelta to reduce to a minimal set of tests to
-# reproduce a failure.
+# A helper script to use delta/singledelta to reduce to a minimal set of
+# tests to reproduce a failure.
 # Sometimes the tests interact in unexpected ways, so you need to run two
 # or three tests in order to cause the failure to occur.  It's tiresome to
 # determine a minimal subset of tests by hand; this script automates it.
 
 # I think https://github.com/DRMacIver/structureshrink would be better than
-# multidelta for this; multidelta requires strange workarounds.  But
-# multidelta is readily available in most distributions' packages, so using
-# that.
+# delta for this; delta requires strange workarounds.  But delta is readily
+# available in most distributions' packages, so using that.
 
 set -ue
 
-if ! which multidelta &>/dev/null
+if ! which singledelta &>/dev/null
 then
-    echo "multidelta not found.  Please install it to use this script" >&2
+    echo "singledelta not found.  Please install it to use this script" >&2
     exit 1
 fi
 
@@ -60,8 +59,7 @@ export REDUCE_TESTS_TEST_EXE=$test_exe
 
 # We have to add braces around the lines to avoid topformflat messing up the file.
 # The braces are removed again inside our helper script.
-"$test_exe" --list-test-names-only '~[.]' | \
-    grep '[^ ]' | sed 's/.*/{&}/' > list_of_tests || true
-multidelta tools/reduce_tests_helper.sh list_of_tests
+"$test_exe" --list-test-names-only '~[.]' | grep '[^ ]' | sed 's/.*/{&}/' > list_of_tests || true
+singledelta -in_place -test=tools/reduce_tests_helper.sh list_of_tests
 
 # vim:tw=0

tools/reduce_tests_helper.sh

@@ -5,11 +5,19 @@
 set -uex
 
 # Disallow empty test list
-if [ ! -s "$multidelta_all_files" ]
+if [ ! -s "$1" ]
 then
     exit 1
 fi
 
+# return 0 iff the expected error is emitted
+
+# If you have a test string to watch for, add it here and comment out the later check for test success.
+#"$REDUCE_TESTS_TEST_EXE" -d yes --rng-seed "$rng_seed" \
+#    $REDUCE_TESTS_EXTRA_OPTS \
+#    -f <(tr -d '{}' < <(cat $1)) 2>&1 | tee -a reduce_tests.log | grep -q '../tests/monster_test.cpp:1008: FAILED:'
+
+
 if "$REDUCE_TESTS_TEST_EXE" -d yes --abort --rng-seed "$rng_seed" \
     $REDUCE_TESTS_EXTRA_OPTS \
     -f <(tr -d '{}' < "$multidelta_all_files")