selftests: mptcp: join: colored results

Thanks to the parent commit, it is easy to change the output and add
some colours to help spotting issues.

The colours are not used if stdout is redirected or if NO_COLOR env var
is set to 1 as specified in https://no-color.org.

It is possible to force displaying the colours even if stdout is
redirected by setting this env var:

  SELFTESTS_MPTCP_LIB_COLOR_FORCE=1

Acked-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Link: https://lore.kernel.org/r/20230730-upstream-net-next-20230728-mptcp-selftests-misc-v1-2-7e9cc530a9cd@tessares.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tools/testing/selftests/net/mptcp/mptcp_join.sh

@@ -215,22 +215,22 @@ print_info()
 	# It can be empty, no need to print anything then
 	[ -z "${1}" ] && return
 
-	printf "%-${nr_blank}sInfo: %s\n" " " "${*}"
+	mptcp_lib_print_info "      Info: ${*}"
 }
 
 print_ok()
 {
-	echo "[ ok ]${1:+ ${*}}"
+	mptcp_lib_print_ok "[ ok ]${1:+ ${*}}"
 }
 
 print_fail()
 {
-	echo "[fail]${1:+ ${*}}"
+	mptcp_lib_print_err "[fail]${1:+ ${*}}"
 }
 
 print_skip()
 {
-	echo "[skip]${1:+ ${*}}"
+	mptcp_lib_print_warn "[skip]${1:+ ${*}}"
 }
 
 # [ $1: fail msg ]

tools/testing/selftests/net/mptcp/mptcp_lib.sh

@@ -4,10 +4,49 @@
 readonly KSFT_PASS=0
 readonly KSFT_FAIL=1
 readonly KSFT_SKIP=4
+
+# shellcheck disable=SC2155 # declare and assign separately
 readonly KSFT_TEST=$(basename "${0}" | sed 's/\.sh$//g')
 
 MPTCP_LIB_SUBTESTS=()
 
+# only if supported (or forced) and not disabled, see no-color.org
+if { [ -t 1 ] || [ "${SELFTESTS_MPTCP_LIB_COLOR_FORCE:-}" = "1" ]; } &&
+   [ "${NO_COLOR:-}" != "1" ]; then
+	readonly MPTCP_LIB_COLOR_RED="\E[1;31m"
+	readonly MPTCP_LIB_COLOR_GREEN="\E[1;32m"
+	readonly MPTCP_LIB_COLOR_YELLOW="\E[1;33m"
+	readonly MPTCP_LIB_COLOR_BLUE="\E[1;34m"
+	readonly MPTCP_LIB_COLOR_RESET="\E[0m"
+else
+	readonly MPTCP_LIB_COLOR_RED=
+	readonly MPTCP_LIB_COLOR_GREEN=
+	readonly MPTCP_LIB_COLOR_YELLOW=
+	readonly MPTCP_LIB_COLOR_BLUE=
+	readonly MPTCP_LIB_COLOR_RESET=
+fi
+
+# $1: color, $2: text
+mptcp_lib_print_color() {
+	echo -e "${MPTCP_LIB_START_PRINT:-}${*}${MPTCP_LIB_COLOR_RESET}"
+}
+
+mptcp_lib_print_ok() {
+	mptcp_lib_print_color "${MPTCP_LIB_COLOR_GREEN}${*}"
+}
+
+mptcp_lib_print_warn() {
+	mptcp_lib_print_color "${MPTCP_LIB_COLOR_YELLOW}${*}"
+}
+
+mptcp_lib_print_info() {
+	mptcp_lib_print_color "${MPTCP_LIB_COLOR_BLUE}${*}"
+}
+
+mptcp_lib_print_err() {
+	mptcp_lib_print_color "${MPTCP_LIB_COLOR_RED}${*}"
+}
+
 # SELFTESTS_MPTCP_LIB_EXPECT_ALL_FEATURES env var can be set when validating all
 # features using the last version of the kernel and the selftests to make sure
 # a test is not being skipped by mistake.