sandbox: add test of CONFIG_ENV_IMPORT_FDT

Check that a variable defined in /config/environment is found in the
run-time environment, and that clearing fdt_env_path from within that
node works.

Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>
[trini: Conditionalize the test being linked in]
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/test/env/Makefile b/test/env/Makefile
index 5c8eae3..9a98fd4 100644
--- a/test/env/Makefile
+++ b/test/env/Makefile
@@ -5,3 +5,4 @@
 obj-y += cmd_ut_env.o
 obj-y += attr.o
 obj-y += hashtable.o
+obj-$(CONFIG_ENV_IMPORT_FDT) += fdt.o
diff --git a/test/env/fdt.c b/test/env/fdt.c
new file mode 100644
index 0000000..30bfa88
--- /dev/null
+++ b/test/env/fdt.c
@@ -0,0 +1,20 @@
+#include <common.h>
+#include <command.h>
+#include <env_attr.h>
+#include <test/env.h>
+#include <test/ut.h>
+
+static int env_test_fdt_import(struct unit_test_state *uts)
+{
+	const char *val;
+
+	val = env_get("from_fdt");
+	ut_assertnonnull(val);
+	ut_asserteq_str("yes", val);
+
+	val = env_get("fdt_env_path");
+	ut_assertnull(val);
+
+	return 0;
+}
+ENV_TEST(env_test_fdt_import, 0);