tests: fix race condition when running sh commands

tests/test_exact_output.rs

@@ -245,38 +245,28 @@ fn apparent_size_output() -> Vec<String> {
 #[cfg_attr(target_os = "windows", ignore)]
 #[test]
 pub fn test_permission_normal() {
-    Command::new("sh")
+    let output = Command::new("sh")
         .arg("-c")
-        .arg("mkdir -p /tmp/unreadable_folder && chmod 000 /tmp/unreadable_folder")
+        .arg("t=\"$(mktemp -d)\" && chmod 000 \"$t\" && printf %s \"$t\"")
         .output()
         .unwrap();
-    let command_args = vec!["/tmp/unreadable_folder"];
+    let tmpdir = String::from_utf8(output.stdout).unwrap();
+    let command_args = vec![&tmpdir];
     let permission_msg = r#"Did not have permissions for all"#.trim().to_string();
     exact_output_test(command_args, vec![], vec![permission_msg]);
-
-    Command::new("sh")
-        .arg("-c")
-        .arg("chmod 555 /tmp/unreadable_folder")
-        .output()
-        .unwrap();
 }
 
 #[cfg_attr(target_os = "windows", ignore)]
 #[test]
 pub fn test_permission_flag() {
-    Command::new("sh")
-        .arg("-c")
-        .arg("mkdir -p /tmp/unreadable_folder && chmod 000 /tmp/unreadable_folder")
-        .output()
-        .unwrap();
+    let output = Command::new("sh")
+    .arg("-c")
+    .arg("t=\"$(mktemp -d)\" && chmod 000 \"$t\" && printf %s \"$t\"")
+    .output()
+    .unwrap();
+    let tmpdir = String::from_utf8(output.stdout).unwrap();
     // add the flag to CLI
-    let command_args = vec!["--print-errors", "/tmp/unreadable_folder"];
+    let command_args = vec!["--print-errors", &tmpdir];
     let permission_msg = r#"Did not have permissions for directories"#.trim().to_string();
     exact_output_test(command_args, vec![], vec![permission_msg]);
-
-    Command::new("sh")
-        .arg("-c")
-        .arg("chmod 555 /tmp/unreadable_folder")
-        .output()
-        .unwrap();
 }