* Added flags to example backend to control its behaviour:

* Start with `-- -r` to run the reset plugin
  * Start with `-- -s` to run the state callback
* Rewrote yang dir load algorithm to follow the algorithm in [FAQ](FAQ(doc/FAQ.md#how-are-yang-files-found) with more precise timestamp checks, etc.

test/test_upgrade_repair.sh

@@ -0,0 +1,145 @@
+#!/bin/bash
+# Start clixon with module A rec 2019
+# Load startup with non-compatible and invalid module A with rev 0814-01-28
+# Go into fail-safe with invalid startup
+
+# Magic line must be first in script (see README.md)
+s="$_" ; . ./lib.sh || if [ "$s" = $0 ]; then exit 0; else return 0; fi
+
+APPNAME=example
+
+cfg=$dir/conf_yang.xml
+fyangA0=$dir/A@0814-01-28.yang
+fyangA1=$dir/A@2019-01-01.yang
+
+# Yang module A revision "0814-01-28"
+# Note that this Yang model will exist in the DIR but will not be loaded
+# by the system. Just here for reference
+# XXX: Maybe it should be loaded and used in draft-wu?
+cat <<EOF > $fyangA0
+module A{
+  prefix a;
+  revision 0814-01-28;
+  namespace "urn:example:a";
+  leaf a0{
+    type string;
+  }
+  leaf a1{
+    type string;
+  }
+}
+EOF
+
+# Yang module A revision "2019-01-01"
+cat <<EOF > $fyangA1
+module A{
+  prefix a;
+  revision 2019-01-01;
+  revision 0814-01-28;
+  namespace "urn:example:a";
+  /*  leaf a0 has been removed */
+  leaf a1{
+    description "exists in both versions";
+    type string;
+  } 
+  leaf a2{
+    description "has been added";
+    type string;
+  }
+}
+EOF
+
+# Create configuration
+cat <<EOF > $cfg
+<clixon-config xmlns="http://clicon.org/config">
+  <CLICON_CONFIGFILE>$cfg</CLICON_CONFIGFILE>
+  <CLICON_YANG_DIR>/usr/local/share/clixon</CLICON_YANG_DIR>
+  <CLICON_YANG_MAIN_DIR>$dir</CLICON_YANG_MAIN_DIR>
+  <CLICON_SOCK>/usr/local/var/$APPNAME/$APPNAME.sock</CLICON_SOCK>
+  <CLICON_BACKEND_DIR>/usr/local/lib/example/backend</CLICON_BACKEND_DIR>
+  <CLICON_BACKEND_PIDFILE>/usr/local/var/$APPNAME/$APPNAME.pidfile</CLICON_BACKEND_PIDFILE>
+  <CLICON_XMLDB_DIR>$dir</CLICON_XMLDB_DIR>
+  <CLICON_XMLDB_PLUGIN>/usr/local/lib/xmldb/text.so</CLICON_XMLDB_PLUGIN>
+  <CLICON_XMLDB_MODSTATE>true</CLICON_XMLDB_MODSTATE>
+  <CLICON_CLISPEC_DIR>/usr/local/lib/$APPNAME/clispec</CLICON_CLISPEC_DIR>
+  <CLICON_CLI_DIR>/usr/local/lib/$APPNAME/cli</CLICON_CLI_DIR>
+  <CLICON_CLI_MODE>$APPNAME</CLICON_CLI_MODE>
+</clixon-config>
+EOF
+
+# Create failsafe db
+cat <<EOF > $dir/failsafe_db
+<config>
+   <a1 xmlns="urn:example:a">always work</a1>
+</config>
+EOF
+
+# Create non-compat startup db
+# startup config XML with following (A obsolete, B OK, C lacking)
+cat <<EOF > $dir/non-compat-invalid.xml
+<config>
+   <modules-state xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-library">
+      <module-set-id>42</module-set-id>
+      <module>
+         <name>A</name>
+         <revision>0814-01-28</revision>
+         <namespace>urn:example:a</namespace>
+      </module>
+   </modules-state>
+   <a0 xmlns="urn:example:a">old version</a0>
+   <a1 xmlns="urn:example:a">always work</a1>
+</config>
+EOF
+
+(cd $dir; rm -f tmp_db candidate_db running_db startup_db) # remove databases
+(cd $dir; cp non-compat-invalid.xml startup_db)
+
+mode=startup
+
+new "test params: -f $cfg"
+# Bring your own backend
+if [ $BE -ne 0 ]; then
+    # kill old backend (if any)
+    new "kill old backend"
+    sudo clixon_backend -zf $cfg
+    if [ $? -ne 0 ]; then
+	err
+    fi
+    new "start backend -s $mode -f $cfg"
+    start_backend -s $mode -f $cfg
+fi
+new "waiting"
+sleep $RCWAIT
+
+new "kill old restconf daemon"
+sudo pkill -u www-data clixon_restconf
+
+new "start restconf daemon"
+start_restconf -f $cfg
+
+new "waiting"
+sleep $RCWAIT
+
+new "Check running db content is failsafe"
+expecteof "$clixon_netconf -qf $cfg" 0 '<rpc><get-config><source><running/></source></get-config></rpc>]]>]]>' '^<rpc-reply><data><a1 xmlns="urn:example:a">always work</a1></data></rpc-reply>]]>]]>$'
+
+#repair    
+
+#exit
+
+new "Kill restconf daemon"
+stop_restconf
+
+if [ $BE -ne 0 ]; then
+    new "Kill backend"
+    # Check if premature kill
+    pid=`pgrep -u root -f clixon_backend`
+    if [ -z "$pid" ]; then
+	err "backend already dead"
+    fi
+    # kill backend
+    stop_backend -f $cfg
+
+    rm -rf $dir
+fi
+