Implement more tests for FDA check

talpid-core/Cargo.toml

@@ -103,3 +103,7 @@ features = [
 
 [build-dependencies]
 tonic-build = { workspace = true, default-features = false, features = ["transport", "prost"] }
+
+
+[dev-dependencies]
+tokio = { workspace = true, features = [ "io-util", "test-util", "time" ] }

talpid-core/src/split_tunnel/macos/process.rs

@@ -127,6 +127,7 @@ enum NeedFda {
 /// Return whether `proc` reports that full-disk access is unavailable based on its output
 /// If it cannot be determined that access is available, it is assumed to be available
 async fn parse_logger_status(
+    // TODO: Remove me
     proc: impl Future<Output = io::Result<ExitStatus>>,
     stdout: impl AsyncRead + Unpin + Send + 'static,
     stderr: impl AsyncRead + Unpin + Send + 'static,
@@ -162,14 +163,6 @@ async fn parse_logger_status(
         biased; need_full_disk_access = &mut need_full_disk_access => {
             need_full_disk_access.unwrap_or(NeedFda::No)
         }
-        proc_result = proc => {
-            if let Ok(_exit_status) = proc_result {
-                // Process exited
-                return need_full_disk_access.await.unwrap_or(NeedFda::No);
-            }
-            // `Child::wait`` returned an error
-            NeedFda::No
-        }
         // Timed out while checking for full-disk access
         _ = deadline => NeedFda::No,
     }
@@ -564,12 +557,29 @@ fn check_os_version_support_inner(version: MacosVersion) -> Result<(), Error> {
 
 #[cfg(test)]
 mod test {
-    use super::{
-        check_os_version_support_inner, parse_logger_status, NeedFda, EARLY_FAIL_TIMEOUT,
-        MIN_OS_VERSION,
-    };
+    use super::*;
+
     use std::{process::ExitStatus, time::Duration};
+
     use talpid_platform_metadata::MacosVersion;
+    use tokio::io::{simplex, AsyncWriteExt};
+
+    /// A mock-version of stdout. [SimplexStream] implements [AsyncRead], so it can be used to test
+    /// [parse_logger_status].
+    fn output(msg: &'static str, lag: Duration) -> impl AsyncRead + Unpin + Send + 'static {
+        // Ensure that 'msg' contains a newline to prevent user errors
+        assert!(
+            msg.contains('\n'),
+            "Message does not contain a newline!! Make sure to add a newline to '{msg}'"
+        );
+        let (stdout_read, mut stdout_write) = simplex(msg.as_bytes().len());
+        //  "print" to "stdout" after `duration`.
+        tokio::spawn(async move {
+            tokio::time::sleep(lag).await;
+            stdout_write.write_all(msg.as_bytes()).await.unwrap();
+        });
+        stdout_read
+    }
 
     #[test]
     fn test_min_os_version() {
@@ -643,4 +653,49 @@ mod test {
             "expected 'NeedFda::No' on immediate exit",
         );
     }
+
+    /// Check that [parse_logger_status] returns within a reasonable timeframe.
+    /// "Reasonable" being within [EARLY_FAIL_TIMEOUT].
+    #[tokio::test]
+    async fn test_parse_logger_status_responsive() {
+        tokio::time::pause();
+        let start = tokio::time::Instant::now();
+        let stdout = output("This will never be printed\n", Duration::MAX);
+        let stderr = output(
+            "ES_NEW_CLIENT_RESULT_ERR_NOT_PERMITTED\n",
+            EARLY_FAIL_TIMEOUT / 2,
+        );
+        tokio::time::resume();
+
+        let need_fda =
+            parse_logger_status(async { Ok(ExitStatus::default()) }, stdout, stderr).await;
+
+        tokio::time::pause();
+
+        assert_eq!(
+            need_fda,
+            NeedFda::Yes,
+            "expected 'NeedFda::Yes' when ES_NEW_CLIENT_RESULT_ERR_NOT_PERMITTED was eventually printed to stderr"
+        );
+
+        // Assert that we did not spend more time waiting than we should
+        assert!(start.elapsed() < EARLY_FAIL_TIMEOUT);
+    }
+
+    /// Check that [parse_logger_status] doesn't get stuck because nothing is ever output
+    /// to std{out,err}.
+    #[tokio::test]
+    async fn test_parse_logger_status_hogged() {
+        let stdout = output("This will never be printed\n", Duration::MAX);
+        let stderr = output("This will never be printed\n", Duration::MAX);
+
+        let need_fda =
+            parse_logger_status(async { Ok(ExitStatus::default()) }, stdout, stderr).await;
+
+        assert_eq!(
+            need_fda,
+            NeedFda::No,
+            "expected 'NeedFda::No' when nothing was ever printed to stdout or stderr"
+        );
+    }
 }