fix: add mutex guard for permission_prompt tests (#4105)

This PR introduces the mutex guard for the test cases which depends on the 
permission prompt mocking utility. permission_request test cases depend on 
the mocked (dummy) value of the permission_prompt result. The value is stored 
at static STUB_PROMPT_VALUE: AtomicBool and these test cases share this 
value. So we should lock at the start of these test cases.

Before this change cargo test permission failed 6 times out of 20. After this 
change, 0 times out of 20 (on my mac).

cli/permissions.rs

@@ -14,6 +14,8 @@ use std::path::{Path, PathBuf};
 use std::sync::atomic::AtomicBool;
 #[cfg(test)]
 use std::sync::atomic::Ordering;
+#[cfg(test)]
+use std::sync::Mutex;
 use url::Url;
 
 const PERMISSION_EMOJI: &str = "⚠️";
@@ -325,6 +327,12 @@ fn permission_prompt(message: &str) -> bool {
   }
 }
 
+#[cfg(test)]
+lazy_static! {
+  /// Lock this when you use `set_prompt_result` in a test case.
+  static ref PERMISSION_PROMPT_GUARD: Mutex<()> = Mutex::new(());
+}
+
 #[cfg(test)]
 static STUB_PROMPT_VALUE: AtomicBool = AtomicBool::new(true);
 
@@ -521,6 +529,7 @@ mod tests {
 
   #[test]
   fn test_permissions_request_run() {
+    let guard = PERMISSION_PROMPT_GUARD.lock().unwrap();
     let mut perms0 = DenoPermissions::from_flags(&DenoFlags {
       ..Default::default()
     });
@@ -532,10 +541,12 @@ mod tests {
     });
     set_prompt_result(false);
     assert_eq!(perms1.request_run(), PermissionState::Deny);
+    drop(guard);
   }
 
   #[test]
   fn test_permissions_request_read() {
+    let guard = PERMISSION_PROMPT_GUARD.lock().unwrap();
     let whitelist = vec![PathBuf::from("/foo/bar")];
     let mut perms0 = DenoPermissions::from_flags(&DenoFlags {
       read_whitelist: whitelist.clone(),
@@ -568,10 +579,12 @@ mod tests {
       perms2.request_read(&Some(Path::new("/foo/baz"))),
       PermissionState::Deny
     );
+    drop(guard);
   }
 
   #[test]
   fn test_permissions_request_write() {
+    let guard = PERMISSION_PROMPT_GUARD.lock().unwrap();
     let whitelist = vec![PathBuf::from("/foo/bar")];
     let mut perms0 = DenoPermissions::from_flags(&DenoFlags {
       write_whitelist: whitelist.clone(),
@@ -604,10 +617,12 @@ mod tests {
       perms2.request_write(&Some(Path::new("/foo/baz"))),
       PermissionState::Deny
     );
+    drop(guard);
   }
 
   #[test]
   fn test_permission_request_net() {
+    let guard = PERMISSION_PROMPT_GUARD.lock().unwrap();
     let whitelist = svec!["localhost:8080"];
 
     let mut perms0 = DenoPermissions::from_flags(&DenoFlags {
@@ -654,10 +669,12 @@ mod tests {
     });
     set_prompt_result(true);
     assert!(perms3.request_net(&Some(":")).is_err());
+    drop(guard);
   }
 
   #[test]
   fn test_permissions_request_env() {
+    let guard = PERMISSION_PROMPT_GUARD.lock().unwrap();
     let mut perms0 = DenoPermissions::from_flags(&DenoFlags {
       ..Default::default()
     });
@@ -669,10 +686,12 @@ mod tests {
     });
     set_prompt_result(false);
     assert_eq!(perms1.request_env(), PermissionState::Deny);
+    drop(guard);
   }
 
   #[test]
   fn test_permissions_request_plugin() {
+    let guard = PERMISSION_PROMPT_GUARD.lock().unwrap();
     let mut perms0 = DenoPermissions::from_flags(&DenoFlags {
       ..Default::default()
     });
@@ -684,10 +703,12 @@ mod tests {
     });
     set_prompt_result(false);
     assert_eq!(perms1.request_plugin(), PermissionState::Deny);
+    drop(guard);
   }
 
   #[test]
   fn test_permissions_request_hrtime() {
+    let guard = PERMISSION_PROMPT_GUARD.lock().unwrap();
     let mut perms0 = DenoPermissions::from_flags(&DenoFlags {
       ..Default::default()
     });
@@ -699,5 +720,6 @@ mod tests {
     });
     set_prompt_result(false);
     assert_eq!(perms1.request_hrtime(), PermissionState::Deny);
+    drop(guard);
   }
 }