test/py: Handle expected reboot while booting sandbox

Add expected_reset optional argument to ConsoleBase::ensure_spawned(),
ConsoleBase::restart_uboot() and ConsoleSandbox::restart_uboot_with_flags()
so that it can handle a reset while the 1st boot process after main
boot logo before prompt correctly.

Signed-off-by: Masami Hiramatsu <masami.hiramatsu@linaro.org>
Reviewed-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>

test/py/u_boot_console_sandbox.py

@@ -57,11 +57,14 @@ class ConsoleSandbox(ConsoleBase):
         cmd += self.sandbox_flags
         return Spawn(cmd, cwd=self.config.source_dir)
 
-    def restart_uboot_with_flags(self, flags):
+    def restart_uboot_with_flags(self, flags, expect_reset=False):
         """Run U-Boot with the given command-line flags
 
         Args:
             flags: List of flags to pass, each a string
+            expect_reset: Boolean indication whether this boot is expected
+                to be reset while the 1st boot process after main boot before
+                prompt. False by default.
 
         Returns:
             A u_boot_spawn.Spawn object that is attached to U-Boot.
@@ -69,7 +72,7 @@ class ConsoleSandbox(ConsoleBase):
 
         try:
             self.sandbox_flags = flags
-            return self.restart_uboot()
+            return self.restart_uboot(expect_reset)
         finally:
             self.sandbox_flags = []