Fix clippy warnings

Fix clippy warnings.

Signed-off-by: Tim Zhang <tim@hyper.sh>

tests/cgroup.rs

@@ -48,7 +48,7 @@ fn test_cgroup_with_relative_paths() {
     let cg = Cgroup::load(h, String::from(cgroup_name));
     {
         let subsystems = cg.subsystems();
-        subsystems.into_iter().for_each(|sub| match sub {
+        subsystems.iter().for_each(|sub| match sub {
             Subsystem::Pid(c) => {
                 let cgroup_path = c.path().to_str().unwrap();
                 let relative_path = "/pids/";

tests/cpuset.rs

@@ -36,7 +36,7 @@ fn test_cpuset_set_cpus() {
             assert_eq!(0, set.cpus.len());
         } else {
             // for cgroup v1, cpuset is copied from parent.
-            assert_eq!(true, set.cpus.len() > 0);
+            assert_eq!(true, !set.cpus.is_empty());
         }
 
         // 0
@@ -48,10 +48,9 @@ fn test_cpuset_set_cpus() {
         assert_eq!((0, 0), set.cpus[0]);
 
         // all cpus in system
-        let cpus =
-            fs::read_to_string("/sys/fs/cgroup/cpuset.cpus.effective").unwrap_or("".to_string());
+        let cpus = fs::read_to_string("/sys/fs/cgroup/cpuset.cpus.effective").unwrap_or_default();
         let cpus = cpus.trim();
-        if cpus != "" {
+        if !cpus.is_empty() {
             let r = cpuset.set_cpus(&cpus);
             assert_eq!(true, r.is_ok());
             let set = cpuset.cpuset();
@@ -73,14 +72,14 @@ fn test_cpuset_set_cpus_add_task() {
         assert_eq!(0, set.cpus.len());
     } else {
         // for cgroup v1, cpuset is copied from parent.
-        assert_eq!(true, set.cpus.len() > 0);
+        assert_eq!(true, !set.cpus.is_empty());
     }
 
     // Add a task to the control group.
     let pid_i = libc::pid_t::from(nix::unistd::getpid()) as u64;
     let _ = cg.add_task(CgroupPid::from(pid_i));
     let tasks = cg.tasks();
-    assert_eq!(true, tasks.len() > 0);
+    assert_eq!(true, !tasks.is_empty());
     println!("tasks after added: {:?}", tasks);
 
     // remove task

tests/devices.rs

@@ -27,7 +27,7 @@ fn test_devices_parsing() {
                 DeviceType::All,
                 -1,
                 -1,
-                &vec![
+                &[
                     DevicePermissions::Read,
                     DevicePermissions::Write,
                     DevicePermissions::MkNod,
@@ -42,7 +42,7 @@ fn test_devices_parsing() {
 
         // Now add mknod access to /dev/null device
         devices
-            .allow_device(DeviceType::Char, 1, 3, &vec![DevicePermissions::MkNod])
+            .allow_device(DeviceType::Char, 1, 3, &[DevicePermissions::MkNod])
             .unwrap();
         let allowed_devices = devices.allowed_devices();
         assert!(allowed_devices.is_ok());

tests/pids.rs

@@ -89,7 +89,7 @@ fn test_pid_events_is_not_zero() {
             Ok(ForkResult::Child) => loop {
                 let pids_max = pids.get_pid_max();
                 if pids_max.is_ok() && pids_max.unwrap() == MaxValue::Value(1) {
-                    if let Err(_) = unsafe { fork() } {
+                    if unsafe { fork() }.is_err() {
                         unsafe { libc::exit(0) };
                     } else {
                         unsafe { libc::exit(1) };