Test for skipping custom sqls based on $SQLS_SIDS

This should not alter the current behaviour, just document it.

Change-Id: I3e575caba790d603787f797d37888a9d466e78d0

agents/plugins/mk_oracle

@@ -2124,6 +2124,13 @@ unset_custom_sqls_vars() {
     unset SQLS_DBUSER SQLS_DBPASSWORD SQLS_DBSYSCONNECT SQLS_TNSALIAS SQLS_ITEM_SID
 }
 
+sid_matches_defined_sids() {
+    # first parameter is a list of coma separated values (SQLS_SIDS)
+    # second parameter is a single value (current sid)
+    sids=${1//,/ }
+    echo "$sids" | "${GREP}" -q "$2"
+}
+
 do_custom_sqls() {
     for section in $custom_sqls_sections; do
         if ! type "$section" >/dev/null 2>&1; then
@@ -2134,11 +2141,8 @@ do_custom_sqls() {
 
         $section
 
-        local sids=${SQLS_SIDS:-$custom_sqls_sids}
-        sids=${sids//,/ }
-
         # If SID is not part of sids we can skip the rest
-        if ! echo "$sids" | "${GREP}" -q "$MK_SID"; then
+        if ! sid_matches_defined_sids "${SQLS_SIDS:-$custom_sqls_sids}" "$MK_SID"; then
             logging -w "[${MK_SID}] [custom_sql] [${section}]" \
                 "Skipping this section, runs only on SIDs '$sids'"
             unset_custom_sqls_vars

tests/unit-shell/agents/plugins/test_mk_oracle.sh

@@ -866,5 +866,16 @@ test_mk_oracle_mk_ora_db_connect_sqls_tnsalias_tnsping_ok_sid_specific_prefix_br
     teardown_tnsping
 }
 
+test_mk_oracle_sid_matches_defined_sids() {
+    assertTrue 'sid_matches_defined_sids "prefixed_value" "prefix"' # THIS IS BROKEN! TODO: should not match!
+    assertTrue 'sid_matches_defined_sids "some,value,here" "value"'
+    assertFalse 'sid_matches_defined_sids "some,hello,here" "value"'
+    # documentation says, that customer may us "$SIDS" when the section should
+    # be executed for all elements, but this variable contains a newline
+    # seperated list of sids:
+    assertTrue 'sid_matches_defined_sids "some\nvalue\nhere" "value"'
+    assertTrue 'sid_matches_defined_sids "some\nprefixed_value\nhere" "value"' # THIS IS BROKEN! TODO: should not match!
+}
+
 # shellcheck disable=SC1090 # Can't follow
 . "$UNIT_SH_SHUNIT2"