tests: Add a test simultaneously set serial and console as TTY mode

Add a test that supports configuring serial and console as TTY mode
at the same time. With this configuration, the VM can set up a legacy
serial device as an early printk console device, and then change to a
virito console device after the virito console device is initialized.

In this case, we can capture the logs printed by legacy serial on early
boot, and later by the virtio console.

Signed-off-by: Yong He <alexyonghe@tencent.com>

tests/integration.rs

@@ -7093,6 +7093,58 @@ mod common_parallel {
 
         handle_child_output(r, &output);
     }
+
+    #[test]
+    #[cfg(target_arch = "x86_64")]
+    fn test_double_tty() {
+        let focal = UbuntuDiskConfig::new(FOCAL_IMAGE_NAME.to_string());
+        let guest = Guest::new(Box::new(focal));
+        let mut cmd = GuestCommand::new(&guest);
+        let api_socket = temp_api_path(&guest.tmp_dir);
+        let tty_str: &str = "console=hvc0 earlyprintk=ttyS0 ";
+        // linux printk module enable console log.
+        let con_dis_str: &str = "console [hvc0] enabled";
+        // linux printk module disable console log.
+        let con_enb_str: &str = "bootconsole [earlyser0] disabled";
+
+        let kernel_path = direct_kernel_boot_path();
+
+        cmd.args(["--cpus", "boot=1"])
+            .args(["--memory", "size=512M"])
+            .args(["--kernel", kernel_path.to_str().unwrap()])
+            .args([
+                "--cmdline",
+                DIRECT_KERNEL_BOOT_CMDLINE
+                    .replace("console=hvc0 ", tty_str)
+                    .as_str(),
+            ])
+            .capture_output()
+            .default_disks()
+            .default_net()
+            .args(["--serial", "tty"])
+            .args(["--console", "tty"])
+            .args(["--api-socket", &api_socket]);
+
+        let mut child = cmd.spawn().unwrap();
+
+        let mut r = std::panic::catch_unwind(|| {
+            guest.wait_vm_boot(None).unwrap();
+        });
+
+        let _ = child.kill();
+        let output = child.wait_with_output().unwrap();
+
+        if r.is_ok() {
+            r = std::panic::catch_unwind(|| {
+                let s = String::from_utf8_lossy(&output.stdout);
+                assert!(s.contains(tty_str));
+                assert!(s.contains(con_dis_str));
+                assert!(s.contains(con_enb_str));
+            });
+        }
+
+        handle_child_output(r, &output);
+    }
 }
 
 mod dbus_api {