kata-ctl: fix permission deny issue in test_add_remove

test_add_remove and test_get_sandbox_id_for_volume need root user, but
test_drop_privs can temporarily change the user to "nobody" that can
lead to the failure of these tests.

Serialise these three tests can fix it.

Fixes: #6055
Signed-off-by: Jianyong Wu <jianyong.wu@arm.com>

src/tools/kata-ctl/Cargo.toml

@@ -30,6 +30,7 @@ shim-interface = { path = "../../libs/shim-interface"}
 kata-types = { path = "../../libs/kata-types" }
 safe-path = { path = "../../libs/safe-path" }
 agent = { path = "../../runtime-rs/crates/agent"}
+serial_test = "0.5.1"
 
 [target.'cfg(target_arch = "s390x")'.dependencies]
 reqwest = { version = "0.11", default-features = false, features = ["json", "blocking", "native-tls"] }

src/tools/kata-ctl/src/ops/volume_ops.rs

@@ -169,11 +169,13 @@ pub fn get_sandbox_id_for_volume(volume_path: &str) -> Result<String> {
 mod tests {
     use super::*;
     use kata_types::mount::DirectVolumeMountInfo;
+    use serial_test::serial;
     use std::{collections::HashMap, fs};
     use tempfile::tempdir;
     use test_utils::skip_if_not_root;
 
     #[test]
+    #[serial]
     fn test_get_sandbox_id_for_volume() {
         // this test has to run as root, so has to manually cleanup afterwards
         skip_if_not_root!();
@@ -259,6 +261,7 @@ mod tests {
     }
 
     #[test]
+    #[serial]
     fn test_add_remove() {
         skip_if_not_root!();
         // example volume dir is a/b/c, note the behavior of join would take "/a" as absolute path.

src/tools/kata-ctl/src/utils.rs

@@ -147,10 +147,12 @@ pub fn get_generic_cpu_details(cpu_info_file: &str) -> Result<(String, String)>
 #[cfg(test)]
 mod tests {
     use super::*;
+    use serial_test::serial;
     use std::io::Write;
     use tempfile::tempdir;
 
     #[test]
+    #[serial]
     fn test_drop_privs() {
         let res = drop_privs();
         assert!(res.is_ok());
@@ -164,6 +166,7 @@ mod tests {
     }
 
     #[test]
+    #[serial]
     fn test_kernel_version_valid_input() {
         let dir = tempdir().unwrap();
         let file_path = dir.path().join("proc-version");
@@ -208,6 +211,7 @@ mod tests {
     }
 
     #[test]
+    #[serial]
     fn test_get_distro_details_valid_file() {
         let dir = tempdir().unwrap();
         let file_path = dir.path().join("os-version");