diff --git a/tests/run-tests.sh b/tests/run-tests.sh
index 2538430..a8ef970 100644
--- a/tests/run-tests.sh
+++ b/tests/run-tests.sh
@@ -1,12 +1,22 @@
 #!/bin/bash
 
+# 1) start server:
+#   without caching:
+#       REDIS_HOST=None CHEATSH_PORT=50000 python bin/srv.py
+#       (recommended)
+#   with caching:
+#       REDIS_PREFIX=TEST1 CHEATSH_PORT=50000 python bin/srv.py 
+#       (for complex search queries + to test caching)
+# 2) configure CHTSH_URL
+# 3) run the script
+
 TMP=$(mktemp /tmp/cht.sh.tests-XXXXXXXXXXXXXX)
 TMP2=$(mktemp /tmp/cht.sh.tests-XXXXXXXXXXXXXX)
 TMP3=$(mktemp /tmp/cht.sh.tests-XXXXXXXXXXXXXX)
 trap 'rm -rf $TMP $TMP2 $TMP3' EXIT
 
 export CHTSH_URL=http://cht.sh:50000
-CHTSH_SCRIPT=$(dirname $(dirname $(readlink -f "$0")))/share/cht.sh.txt
+CHTSH_SCRIPT=$(dirname "$(dirname "$(readlink -f "$0")")")/share/cht.sh.txt
 
 i=0
 failed=0
@@ -14,7 +24,7 @@ failed=0
   if [ -z "$1" ]; then
     cat -n tests.txt
   else
-    cat -n tests.txt | sed -n "$(echo $* | sed 's/ /p; /g;s/$/p/')"
+    cat -n tests.txt | sed -n "$(echo "$*" | sed 's/ /p; /g;s/$/p/')"
   fi
 } > "$TMP3"
 while read -r number test_line; do
@@ -25,14 +35,13 @@ while read -r number test_line; do
   else
     eval "curl -s $CHTSH_URL/$test_line" > "$TMP"
   fi
-  diff results/"$number" "$TMP" > "$TMP2"
-  if [ "$?" != 0 ]; then
+  if ! diff results/"$number" "$TMP" > "$TMP2"; then
     echo "FAILED: [$number] $test_line"
     ((failed++))
   fi
   ((i++))
 done < "$TMP3"
 
-echo TESTS/OK/FAILED "$i/$[i-failed]/$failed"
+echo TESTS/OK/FAILED "$i/$((i-failed))/$failed"