[171-keactrl-tests-not-posix] Replaced not portable '+''

src/bin/keactrl/tests/keactrl_tests.sh.in

@@ -1420,21 +1420,22 @@ version_command_test() {
     test_start "keactrl.version-command"
 
     # Create configuration file for keactrl.
+    # Note that += is NOT in POSIX shell so PLEASE do NOT use it.
     keactrl_config="${CFG_FILES}\ndhcp4=yes\ndhcp6=yes\ndhcp_ddns=yes\n"
-    keactrl_config+="ctrl_agent=yes\nnetconf=yes\n"
-    keactrl_config+="kea_verbose=no\n${keactrl_fixed_config}"
+    keactrl_config="${keactrl_config}ctrl_agent=yes\nnetconf=yes\n"
+    keactrl_config="${keactrl_config}kea_verbose=no\n${keactrl_fixed_config}"
     create_keactrl_config "${keactrl_config}"
 
     # This is what we expect to get. We need to run it through printf
     # to convert \n to actual LF (0xa) or whatever the EOL is used on your
     # system.
     exp="keactrl: @PACKAGE_VERSION@\n"
-    exp+="kea-dhcp4: @PACKAGE_VERSION@\n"
-    exp+="kea-dhcp6: @PACKAGE_VERSION@\n"
-    exp+="kea-dhcp-ddns: @PACKAGE_VERSION@\n"
-    exp+="kea-ctrl-agent: @PACKAGE_VERSION@"
+    exp="${exp}kea-dhcp4: @PACKAGE_VERSION@\n"
+    exp="${exp}kea-dhcp6: @PACKAGE_VERSION@\n"
+    exp="${exp}kea-dhcp-ddns: @PACKAGE_VERSION@\n"
+    exp="${exp}kea-ctrl-agent: @PACKAGE_VERSION@"
     if [ ${have_netconf} -eq 1 ]; then
-        exp+="\nkea-netconf: @PACKAGE_VERSION@"
+        exp="${exp}\nkea-netconf: @PACKAGE_VERSION@"
     fi
     # The %b parameter tells printf to interpret backslashes.
     EXPECTED_RESP=$(printf "%b" "$exp")