log the output of list-changes to a separate file for easier reading

Having the rather complex output of list-changes mixed in with the
main job log can make it difficult to read. Continue to include the
data in the main log file but also write it to a separate file that is
easier to consume.

Change-Id: If4d3b56c76b2bf513b2d44ffedf5825f562f4bfb
Signed-off-by: Doug Hellmann <doug@doughellmann.com>

tools/tox-log-command.sh

@@ -0,0 +1,32 @@
+#!/bin/bash
+#
+# Thin wrapper around list-changes to write a log file in addition to
+# writing to stdout.
+#
+# All Rights Reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+cmd="$1"
+shift
+
+if [ -z "$LOGDIR" ]; then
+    echo "LOGDIR variable not set."
+    exit 1
+fi
+
+logfile="$LOGDIR/$cmd-results.log"
+
+echo "Logging $cmd output to $logfile"
+
+$cmd "$@" 2>&1 | tee "$logfile"

tox.ini

@@ -28,7 +28,9 @@ commands =
 [testenv:list-changes]
 setenv =
     PYTHONUNBUFFERED=1
-commands = list-changes {posargs}
+    LOGDIR={envdir}/log
+commands =
+    {toxinidir}/tools/tox-log-command.sh list-changes {posargs}
 
 [testenv:pep8]
 deps = flake8>=2.2.4,<=2.4.1