Introduce ProcessMonitoringTests

Author: iCharlesHu

Sources/Subprocess/Error.swift

@@ -111,7 +111,7 @@ extension SubprocessError: CustomStringConvertible, CustomDebugStringConvertible
         case .failedToWriteToSubprocess:
             return "Failed to write bytes to the child process."
         case .failedToMonitorProcess:
-            return "Failed to monitor the state of child process with underlying error: \(self.underlyingError!)"
+            return "Failed to monitor the state of child process with underlying error: \(self.underlyingError == nil ? "nil" : "\(self.underlyingError!)")"
         case .streamOutputExceedsLimit(let limit):
             return "Failed to create output from current buffer because the output limit (\(limit)) was reached."
         case .asyncIOFailed(let reason):

Sources/Subprocess/Platforms/Subprocess+Linux.swift

@@ -447,7 +447,7 @@ private struct MonitorThreadContext: Sendable {
     }
 }
 
-private extension siginfo_t {
+internal extension siginfo_t {
     var si_status: Int32 {
         #if canImport(Glibc)
         return _sifields._sigchld.si_status
@@ -700,7 +700,7 @@ private let setup: () = {
 }()
 
 
-private func _setupMonitorSignalHandler() {
+internal func _setupMonitorSignalHandler() {
     // Only executed once
     setup
 }

Sources/Subprocess/Platforms/Subprocess+Windows.swift

@@ -592,7 +592,7 @@ internal func monitorProcessTermination(
         }
     }
 
-    try? await withCheckedThrowingContinuation { (continuation: CheckedContinuation<Void, any Error>) in
+    try await withCheckedThrowingContinuation { (continuation: CheckedContinuation<Void, any Error>) in
         // Set up a callback that immediately resumes the continuation and does no
         // other work.
         let context = Unmanaged.passRetained(continuation as AnyObject).toOpaque()

Tests/SubprocessTests/DarwinTests.swift

@@ -39,7 +39,10 @@ struct SubprocessDarwinTests {
         #expect(idResult.terminationStatus == .exited(1234567))
     }
 
-    @Test func testSubprocessPlatformOptionsPreExecProcessActionAndProcessConfigurator() async throws {
+    @Test(
+        .disabled("Constantly fails on macOS 26 and Swift 6.2"),
+        .bug("https://github.com/swiftlang/swift-subprocess/issues/148")
+    ) func testSubprocessPlatformOptionsPreExecProcessActionAndProcessConfigurator() async throws {
         let (readFD, writeFD) = try FileDescriptor.pipe()
         try await readFD.closeAfter {
             let childPID = try await writeFD.closeAfter {
@@ -165,4 +168,38 @@ struct SubprocessDarwinTests {
     }
 }
 
+extension FileDescriptor {
+    internal func readUntilEOF(upToLength maxLength: Int) async throws -> Data {
+        return try await withCheckedThrowingContinuation { (continuation: CheckedContinuation<Data, any Error>) in
+            let dispatchIO = DispatchIO(
+                type: .stream,
+                fileDescriptor: self.rawValue,
+                queue: .global()
+            ) { error in
+                if error != 0 {
+                    continuation.resume(throwing: POSIXError(.init(rawValue: error) ?? .ENODEV))
+                }
+            }
+            var buffer: Data = Data()
+            dispatchIO.read(
+                offset: 0,
+                length: maxLength,
+                queue: .global()
+            ) { done, data, error in
+                guard error == 0 else {
+                    continuation.resume(throwing: POSIXError(.init(rawValue: error) ?? .ENODEV))
+                    return
+                }
+                if let data = data {
+                    buffer += Data(data)
+                }
+                if done {
+                    dispatchIO.close()
+                    continuation.resume(returning: buffer)
+                }
+            }
+        }
+    }
+}
+
 #endif  // canImport(Darwin)

Tests/SubprocessTests/IntegrationTests.swift

@@ -1577,8 +1577,9 @@ extension SubprocessIntegrationTests {
     @Test func testTerminateProcess() async throws {
         #if os(Windows)
         let setup = TestSetup(
-            executable: .name("cmd.exe"),
-            arguments: ["/c", "timeout /t 99999 >nul"])
+            executable: .name("powershell.exe"),
+            arguments: ["-Command", "Start-Sleep -Seconds 9999"]
+        )
         #else
         let setup = TestSetup(
             executable: .path("/bin/sleep"),
@@ -1789,8 +1790,8 @@ extension SubprocessIntegrationTests {
 
         #if os(Windows)
         let setup = TestSetup(
-            executable: .name("cmd.exe"),
-            arguments: ["/c", "timeout /t 100000 /nobreak"]
+            executable: .name("powershell.exe"),
+            arguments: ["-Command", "Start-Sleep -Seconds 9999"]
         )
         #else
         let setup = TestSetup(
@@ -2267,3 +2268,29 @@ func _run<Result>(
     )
 }
 
+extension FileDescriptor {
+    /// Runs a closure and then closes the FileDescriptor, even if an error occurs.
+    ///
+    /// - Parameter body: The closure to run.
+    ///   If the closure throws an error,
+    ///   this method closes the file descriptor before it rethrows that error.
+    ///
+    /// - Returns: The value returned by the closure.
+    ///
+    /// If `body` throws an error
+    /// or an error occurs while closing the file descriptor,
+    /// this method rethrows that error.
+    public func closeAfter<R>(_ body: () async throws -> R) async throws -> R {
+        // No underscore helper, since the closure's throw isn't necessarily typed.
+        let result: R
+        do {
+            result = try await body()
+        } catch {
+            _ = try? self.close() // Squash close error and throw closure's
+            throw error
+        }
+        try self.close()
+        return result
+    }
+}
+