test: add test for dropped trace before log_init

Add test for dropped trace before log_init, displayed by debug uart.

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/sandbox/cpu/start.c b/arch/sandbox/cpu/start.c
index 8322ed7a..2d18d9d 100644
--- a/arch/sandbox/cpu/start.c
+++ b/arch/sandbox/cpu/start.c
@@ -9,6 +9,7 @@
 #include <efi_loader.h>
 #include <errno.h>
 #include <init.h>
+#include <log.h>
 #include <os.h>
 #include <cli.h>
 #include <sort.h>
@@ -486,6 +487,10 @@
 	 */
 	gd->reloc_off = (ulong)gd->arch.text_base;
 
+	/* sandbox test: log functions called before log_init in board_init_f */
+	log_info("sandbox: starting...\n");
+	log_debug("debug: %s\n", __func__);
+
 	/* Do pre- and post-relocation init */
 	board_init_f(0);
 
diff --git a/test/py/tests/test_log.py b/test/py/tests/test_log.py
index 387b392..f889120 100644
--- a/test/py/tests/test_log.py
+++ b/test/py/tests/test_log.py
@@ -36,3 +36,14 @@
         run_with_format('FLfm', 'file.c:123-func() msg')
         run_with_format('lm', 'NOTICE. msg')
         run_with_format('m', 'msg')
+
+@pytest.mark.buildconfigspec('debug_uart')
+@pytest.mark.boardspec('sandbox')
+def test_log_dropped(u_boot_console):
+    """Test dropped 'log' message when debug_uart is activated"""
+
+    cons = u_boot_console
+    cons.restart_uboot()
+    output = cons.get_spawn_output().replace('\r', '')
+    assert 'sandbox: starting...' in output
+    assert (not 'debug: main' in output)