Provide and suggest update-test.sh in CONTRIBUTING

Provide shell script to update the output for a single test, and suggest
using it in CONTRIBUTING.

2 files changed, 17 insertions, 1 deletions

diff --git a/CONTRIBUTING b/CONTRIBUTING
index 0f4a5d85..cc312dff 100644
--- a/CONTRIBUTING
+++ b/CONTRIBUTING
@@ -80,9 +80,11 @@ How to add new code and to update existing code
    Each line in this file has the following format:
    test-name   sample.pcap   sample.out   tcpdump-options
 
-   the sample.out file can be build by:
+   The sample.out file can be build by:
    (cd tests && ../tcpdump -n -t -r sample.pcap tcpdump-options > sample.out)
 
+   Or, for convenience, use "./update-test.sh test-name"
+
    It is often useful to have test outputs with different verbosity levels
    (none, -v, -vv, -vvv, etc.) depending on the code.
 
diff --git a/update-test.sh b/update-test.sh
new file mode 100755
index 00000000..60359d48
--- /dev/null
+++ b/update-test.sh
@@ -0,0 +1,14 @@
+#!/bin/sh
+TEST="$1"
+PREFIX=tests
+MATCH=0
+while read name input output options
+do
+    [ _$name = _ ] && continue		# ignore empty lines
+    [ _${name#\#} != _$name ] && continue	# ignore comment lines
+    [ $name != "$TEST" ] && continue	# not the requested test
+    [ _$output = _ ] && continue	# ignore incomplete lines
+    MATCH=1
+    ./tcpdump -n -t -r "$PREFIX/$input" $options >"$PREFIX/$output"
+done < $PREFIX/TESTLIST
+[ $MATCH = 0 ] && echo "test $TEST not found" >&2