go-check MockCommand mocking of a fully verifying argument script

example.go

func mockRealSystemdMountInBash(c *C, expArgs [][]string) *testutil.MockCmd {
	stateCallFile := filepath.Join(c.MkDir(), "systemd-mount-state-call")

	template := fmt.Sprintf(`
STATE_FILE=%s
if [ ! -f "$STATE_FILE" ]; then
	CALL_NUM=0
else
	CALL_NUM=$(cat "$STATE_FILE")
fi
CALL_NUM=$(( CALL_NUM + 1 ))
echo "${CALL_NUM}" > "$STATE_FILE"

ALL_ARGS="$*"

#set -x 
#exec 2>&1

fail() {
	echo "unexpected systemd-mount call: ${ALL_ARGS}"
	exit 1
}

case "${CALL_NUM}" in

`, stateCallFile)

	for i, args := range expArgs {
		argsAsString := strings.Join(args, " ")
		caseStr := fmt.Sprintf(`
%d)
	test "${ALL_ARGS}" = %q || fail ;;
`,
			i+1,
			argsAsString,
		)

		template += caseStr
	}

	// add the closing bit to the case
	template += `
	*)
		fail
esac
`
	return testutil.MockCommand(c, "systemd-mount", template)
}