sandbox: Add basic test for command execution

Since run_command() and run_command_list() are important and a little
confusing, add some basic tests to check that the behaviour is correct.

Note: I am not sure that this should be committed, nor where it should go
in the source tree. Comments welcome.

To run the unit tests use the ut_cmd command available in sandbox:

make sandbox_config
make
./u-boot -c ut_cmd

(To test both hush and built-in parsers, you need to manually change
CONFIG_SYS_HUSH_PARSER in include/configs/sandbox.h and build/run again)

Signed-off-by: Simon Glass <sjg@chromium.org>

test/Makefile

@@ -0,0 +1,45 @@
+#
+# (C) Copyright 2012 The Chromium Authors
+#
+# See file CREDITS for list of people who contributed to this
+# project.
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License as
+# published by the Free Software Foundation; either version 2 of
+# the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+# MA 02111-1307 USA
+#
+
+include $(TOPDIR)/config.mk
+
+LIB	= $(obj)libtest.o
+
+COBJS-$(CONFIG_SANDBOX) += command_ut.o
+
+COBJS	:= $(sort $(COBJS-y))
+SRCS	:= $(COBJS:.o=.c)
+OBJS	:= $(addprefix $(obj),$(COBJS))
+
+all:	$(LIB) $(XOBJS)
+
+$(LIB): $(obj).depend $(OBJS)
+	$(call cmd_link_o_target, $(OBJS))
+
+#########################################################################
+
+# defines $(obj).depend target
+include $(SRCTREE)/rules.mk
+
+sinclude $(obj).depend
+
+#########################################################################