tests: extract _test_dmi_oem_strings to tests_wrappers

Move the DMI OEM strings test logic from integration.rs
into a shared _test_dmi_oem_strings() function in
tests_wrappers.rs. The original test in integration.rs
now uses the basic_regular_guest! macro and delegates to
this shared function, enabling reuse by CVM tests.

Signed-off-by: Muminul Islam <muislam@microsoft.com>

cloud-hypervisor/tests/common/tests_wrappers.rs

@@ -2239,3 +2239,53 @@ pub(crate) fn _test_dmi_uuid(guest: &Guest) {
 
     handle_child_output(r, &output);
 }
+
+pub(crate) fn _test_dmi_oem_strings(guest: &Guest) {
+    let s1 = "io.systemd.credential:xx=yy";
+    let s2 = "This is a test string";
+
+    let oem_strings = format!("oem_strings=[{s1},{s2}]");
+
+    let mut child = GuestCommand::new(guest)
+        .default_cpus()
+        .default_memory()
+        .default_kernel_cmdline_with_platform(Some(&oem_strings))
+        .default_disks()
+        .default_net()
+        .capture_output()
+        .spawn()
+        .unwrap();
+
+    let r = std::panic::catch_unwind(|| {
+        guest.wait_vm_boot().unwrap();
+
+        assert_eq!(
+            guest
+                .ssh_command("sudo dmidecode --oem-string count")
+                .unwrap()
+                .trim(),
+            "2"
+        );
+
+        assert_eq!(
+            guest
+                .ssh_command("sudo dmidecode --oem-string 1")
+                .unwrap()
+                .trim(),
+            s1
+        );
+
+        assert_eq!(
+            guest
+                .ssh_command("sudo dmidecode --oem-string 2")
+                .unwrap()
+                .trim(),
+            s2
+        );
+    });
+
+    kill_child(&mut child);
+    let output = child.wait_with_output().unwrap();
+
+    handle_child_output(r, &output);
+}